[PATCH v4 00/25] drm/dumb-buffers: Fix and improve buffer-size calculation

[PATCH v4 00/25] drm/dumb-buffers: Fix and improve buffer-size calculation

[Thomas Zimmermann]

Dumb-buffer pitch and size is specified by width, height, bits-per-pixel
plus various hardware-specific alignments. The calculation of these
values is inconsistent and duplicated among drivers. The results for
formats with bpp < 8 are sometimes incorrect.

This series fixes this for most drivers. Default scanline pitch and
buffer size are now calculated with the existing 4CC helpers. There is
a new helper drm_mode_size_dumb() that calculates scanline pitch and
buffer size according to driver requirements.

The series fixes the common GEM implementations for DMA, SHMEM and
VRAM. It further changes most implementations of dumb_create to use
the new helper. A small number of drivers has more complicated
calculations and will be updated by a later patches.

v4:
- improve UAPI documentation
- document bpp special cases
- use drm_warn_once()
- add TODO lists
- armada: fix pitch alignment
v3:
- document UAPI semantics
- fall back to bpp-based allocation for unknown color modes
- cleanups
v2:
- rewrite series
- convert many individual drivers besides the shared GEM helpers

Thomas Zimmermann (25):
  drm/dumb-buffers: Sanitize output on errors
  drm/dumb-buffers: Provide helper to set pitch and size
  drm/gem-dma: Compute dumb-buffer sizes with drm_mode_size_dumb()
  drm/gem-shmem: Compute dumb-buffer sizes with drm_mode_size_dumb()
  drm/gem-vram: Compute dumb-buffer sizes with drm_mode_size_dumb()
  drm/armada: Compute dumb-buffer sizes with drm_mode_size_dumb()
  drm/exynos: Compute dumb-buffer sizes with drm_mode_size_dumb()
  drm/gma500: Compute dumb-buffer sizes with drm_mode_size_dumb()
  drm/hibmc: Compute dumb-buffer sizes with drm_mode_size_dumb()
  drm/imx/ipuv3: Compute dumb-buffer sizes with drm_mode_size_dumb()
  drm/loongson: Compute dumb-buffer sizes with drm_mode_size_dumb()
  drm/mediatek: Compute dumb-buffer sizes with drm_mode_size_dumb()
  drm/msm: Compute dumb-buffer sizes with drm_mode_size_dumb()
  drm/nouveau: Compute dumb-buffer sizes with drm_mode_size_dumb()
  drm/omapdrm: Compute dumb-buffer sizes with drm_mode_size_dumb()
  drm/qxl: Compute dumb-buffer sizes with drm_mode_size_dumb()
  drm/renesas/rcar-du: Compute dumb-buffer sizes with
    drm_mode_size_dumb()
  drm/renesas/rz-du: Compute dumb-buffer sizes with drm_mode_size_dumb()
  drm/rockchip: Compute dumb-buffer sizes with drm_mode_size_dumb()
  drm/tegra: Compute dumb-buffer sizes with drm_mode_size_dumb()
  drm/virtio: Compute dumb-buffer sizes with drm_mode_size_dumb()
  drm/vmwgfx: Compute dumb-buffer sizes with drm_mode_size_dumb()
  drm/xe: Compute dumb-buffer sizes with drm_mode_size_dumb()
  drm/xen: Compute dumb-buffer sizes with drm_mode_size_dumb()
  drm/xlnx: Compute dumb-buffer sizes with drm_mode_size_dumb()

 Documentation/gpu/todo.rst                    |  28 +++
 drivers/gpu/drm/armada/armada_gem.c           |  16 +-
 drivers/gpu/drm/drm_dumb_buffers.c            | 172 ++++++++++++++++--
 drivers/gpu/drm/drm_gem_dma_helper.c          |   7 +-
 drivers/gpu/drm/drm_gem_shmem_helper.c        |  16 +-
 drivers/gpu/drm/drm_gem_vram_helper.c         |  89 +++------
 drivers/gpu/drm/exynos/exynos_drm_gem.c       |   8 +-
 drivers/gpu/drm/gma500/gem.c                  |  21 +--
 .../gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c   |  25 ++-
 drivers/gpu/drm/imx/ipuv3/imx-drm-core.c      |  29 ++-
 drivers/gpu/drm/loongson/lsdc_gem.c           |  29 +--
 drivers/gpu/drm/mediatek/mtk_gem.c            |  13 +-
 drivers/gpu/drm/msm/msm_gem.c                 |  27 ++-
 drivers/gpu/drm/nouveau/nouveau_display.c     |   7 +-
 drivers/gpu/drm/omapdrm/omap_gem.c            |  15 +-
 drivers/gpu/drm/qxl/qxl_dumb.c                |  17 +-
 drivers/gpu/drm/renesas/rcar-du/rcar_du_kms.c |   7 +-
 drivers/gpu/drm/renesas/rz-du/rzg2l_du_kms.c  |   7 +-
 drivers/gpu/drm/rockchip/rockchip_drm_gem.c   |  12 +-
 drivers/gpu/drm/tegra/gem.c                   |   8 +-
 drivers/gpu/drm/virtio/virtgpu_gem.c          |  11 +-
 drivers/gpu/drm/vmwgfx/vmwgfx_surface.c       |  21 +--
 drivers/gpu/drm/xe/xe_bo.c                    |   8 +-
 drivers/gpu/drm/xen/xen_drm_front.c           |   7 +-
 drivers/gpu/drm/xlnx/zynqmp_kms.c             |   7 +-
 include/drm/drm_dumb_buffers.h                |  14 ++
 include/drm/drm_gem_vram_helper.h             |   6 -
 include/uapi/drm/drm_mode.h                   |  50 ++++-
 28 files changed, 449 insertions(+), 228 deletions(-)
 create mode 100644 include/drm/drm_dumb_buffers.h

-- 
2.48.1

[PATCH v4 01/25] drm/dumb-buffers: Sanitize output on errors

[Thomas Zimmermann]

The ioctls MODE_CREATE_DUMB and MODE_MAP_DUMB return results into a
memory buffer supplied by user space. On errors, it is possible that
intermediate values are being returned. The exact semantics depends
on the DRM driver's implementation of these ioctls. Although this is
most-likely not a security problem in practice, avoid any uncertainty
by clearing the memory to 0 on errors.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/drm_dumb_buffers.c | 40 ++++++++++++++++++++++--------
 1 file changed, 29 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/drm_dumb_buffers.c b/drivers/gpu/drm/drm_dumb_buffers.c
index 70032bba1c97..9916aaf5b3f2 100644
--- a/drivers/gpu/drm/drm_dumb_buffers.c
+++ b/drivers/gpu/drm/drm_dumb_buffers.c
@@ -99,7 +99,30 @@ int drm_mode_create_dumb(struct drm_device *dev,
 int drm_mode_create_dumb_ioctl(struct drm_device *dev,
 			       void *data, struct drm_file *file_priv)
 {
-	return drm_mode_create_dumb(dev, data, file_priv);
+	struct drm_mode_create_dumb *args = data;
+	int err;
+
+	err = drm_mode_create_dumb(dev, args, file_priv);
+	if (err) {
+		args->handle = 0;
+		args->pitch = 0;
+		args->size = 0;
+	}
+	return err;
+}
+
+static int drm_mode_mmap_dumb(struct drm_device *dev, struct drm_mode_map_dumb *args,
+			      struct drm_file *file_priv)
+{
+	if (!dev->driver->dumb_create)
+		return -ENOSYS;
+
+	if (dev->driver->dumb_map_offset)
+		return dev->driver->dumb_map_offset(file_priv, dev, args->handle,
+						    &args->offset);
+	else
+		return drm_gem_dumb_map_offset(file_priv, dev, args->handle,
+					       &args->offset);
 }
 
 /**
@@ -120,17 +143,12 @@ int drm_mode_mmap_dumb_ioctl(struct drm_device *dev,
 			     void *data, struct drm_file *file_priv)
 {
 	struct drm_mode_map_dumb *args = data;
+	int err;
 
-	if (!dev->driver->dumb_create)
-		return -ENOSYS;
-
-	if (dev->driver->dumb_map_offset)
-		return dev->driver->dumb_map_offset(file_priv, dev,
-						    args->handle,
-						    &args->offset);
-	else
-		return drm_gem_dumb_map_offset(file_priv, dev, args->handle,
-					       &args->offset);
+	err = drm_mode_mmap_dumb(dev, args, file_priv);
+	if (err)
+		args->offset = 0;
+	return err;
 }
 
 int drm_mode_destroy_dumb(struct drm_device *dev, u32 handle,
-- 
2.48.1

Re: [PATCH v4 01/25] drm/dumb-buffers: Sanitize output on errors

[Tomi Valkeinen]

Hi,

On 11/03/2025 17:47, Thomas Zimmermann wrote:
> The ioctls MODE_CREATE_DUMB and MODE_MAP_DUMB return results into a
> memory buffer supplied by user space. On errors, it is possible that
> intermediate values are being returned. The exact semantics depends
> on the DRM driver's implementation of these ioctls. Although this is
> most-likely not a security problem in practice, avoid any uncertainty
> by clearing the memory to 0 on errors.
> 
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> ---
>  drivers/gpu/drm/drm_dumb_buffers.c | 40 ++++++++++++++++++++++--------
>  1 file changed, 29 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_dumb_buffers.c b/drivers/gpu/drm/drm_dumb_buffers.c
> index 70032bba1c97..9916aaf5b3f2 100644
> --- a/drivers/gpu/drm/drm_dumb_buffers.c
> +++ b/drivers/gpu/drm/drm_dumb_buffers.c
> @@ -99,7 +99,30 @@ int drm_mode_create_dumb(struct drm_device *dev,
>  int drm_mode_create_dumb_ioctl(struct drm_device *dev,
>  			       void *data, struct drm_file *file_priv)
>  {
> -	return drm_mode_create_dumb(dev, data, file_priv);
> +	struct drm_mode_create_dumb *args = data;
> +	int err;
> +
> +	err = drm_mode_create_dumb(dev, args, file_priv);
> +	if (err) {
> +		args->handle = 0;
> +		args->pitch = 0;
> +		args->size = 0;
> +	}
> +	return err;
> +}
> +
> +static int drm_mode_mmap_dumb(struct drm_device *dev, struct drm_mode_map_dumb *args,
> +			      struct drm_file *file_priv)
> +{
> +	if (!dev->driver->dumb_create)
> +		return -ENOSYS;
> +
> +	if (dev->driver->dumb_map_offset)
> +		return dev->driver->dumb_map_offset(file_priv, dev, args->handle,
> +						    &args->offset);
> +	else
> +		return drm_gem_dumb_map_offset(file_priv, dev, args->handle,
> +					       &args->offset);
>  }
>  
>  /**
> @@ -120,17 +143,12 @@ int drm_mode_mmap_dumb_ioctl(struct drm_device *dev,
>  			     void *data, struct drm_file *file_priv)
>  {
>  	struct drm_mode_map_dumb *args = data;
> +	int err;
>  
> -	if (!dev->driver->dumb_create)
> -		return -ENOSYS;
> -
> -	if (dev->driver->dumb_map_offset)
> -		return dev->driver->dumb_map_offset(file_priv, dev,
> -						    args->handle,
> -						    &args->offset);
> -	else
> -		return drm_gem_dumb_map_offset(file_priv, dev, args->handle,
> -					       &args->offset);
> +	err = drm_mode_mmap_dumb(dev, args, file_priv);
> +	if (err)
> +		args->offset = 0;
> +	return err;
>  }
>  
>  int drm_mode_destroy_dumb(struct drm_device *dev, u32 handle,

Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>

 Tomi

[PATCH v4 02/25] drm/dumb-buffers: Provide helper to set pitch and size

[Thomas Zimmermann]

Add drm_modes_size_dumb(), a helper to calculate the dumb-buffer
scanline pitch and allocation size. Implementations of struct
drm_driver.dumb_create can call the new helper for their size
computations.

There is currently quite a bit of code duplication among DRM's
memory managers. Each calculates scanline pitch and buffer size
from the given arguments, but the implementations are inconsistent
in how they treat alignment and format support. Later patches will
unify this code on top of drm_mode_size_dumb() as much as possible.

drm_mode_size_dumb() uses existing 4CC format helpers to interpret
the given color mode. This makes the dumb-buffer interface behave
similar the kernel's video= parameter. Current per-driver implementations
again likely have subtle differences or bugs in how they support color
modes.

The dumb-buffer UAPI is only specified for known color modes. These
values describe linear, single-plane RGB color formats or legacy index
formats. Other values should not be specified. But some user space
still does. So for unknown color modes, there are a number of known
exceptions for which drm_mode_size_dumb() calculates the pitch from
the bpp value, as before. All other values work the same but print
an error.

v4:
- use %u conversion specifier (Geert)
- list DRM_FORMAT_Dn in UAPI docs (Geert)
- avoid dmesg spamming with drm_warn_once() (Sima)
- add more information about bpp special case (Sima)
- clarify parameters for hardware alignment
- add a TODO item for DUMB_CREATE2
v3:
- document the UAPI semantics
- compute scanline pitch from for unknown color modes (Andy, Tomi)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 Documentation/gpu/todo.rst         |  28 ++++++
 drivers/gpu/drm/drm_dumb_buffers.c | 132 +++++++++++++++++++++++++++++
 include/drm/drm_dumb_buffers.h     |  14 +++
 include/uapi/drm/drm_mode.h        |  50 ++++++++++-
 4 files changed, 223 insertions(+), 1 deletion(-)
 create mode 100644 include/drm/drm_dumb_buffers.h

diff --git a/Documentation/gpu/todo.rst b/Documentation/gpu/todo.rst
index c57777a24e03..f1bd741b06dc 100644
--- a/Documentation/gpu/todo.rst
+++ b/Documentation/gpu/todo.rst
@@ -515,6 +515,34 @@ Contact: Douglas Anderson <dianders@chromium.org>
 
 Level: Starter
 
+Implement a new DUMB_CREATE2 ioctl
+----------------------------------
+
+The current DUMB_CREATE ioctl is not well defined. Instead of a pixel and
+framebuffer format, it only accepts a color mode of vague semantics. Assuming
+a linear framebuffer, the color mode gives and idea of the supported pixel
+format. But userspace effectively has to guess the correct values. It really
+only works reliable with framebuffers in XRGB8888. Userspace has begun to
+workaround these limitations by computing arbitrary format's buffer sizes and
+calculating their sizes in terms of XRGB8888 pixels.
+
+One possible solution is a new ioctl DUMB_CREATE2. It should accept a DRM
+format and a format modifier to resolve the color mode's ambiguity. As
+framebuffers can be multi-planar, the new ioctl has to return the buffer size,
+pitch and GEM handle for each individual color plane.
+
+In the first step, the new ioctl can be limited to the current features of
+the existing DUMB_CREATE. Individual drivers can then be extended to support
+multi-planar formats. Rockchip might require this and would be a good candidate.
+
+In addition to the kernel implementation, there must be user-space support
+for the new ioctl. There's code in Mesa that might be able to use the new
+call.
+
+Contact: Thomas Zimmermann <tzimmermann@suse.de>
+
+Level: Advanced
+
 
 Core refactorings
 =================
diff --git a/drivers/gpu/drm/drm_dumb_buffers.c b/drivers/gpu/drm/drm_dumb_buffers.c
index 9916aaf5b3f2..97cd3dcb79f1 100644
--- a/drivers/gpu/drm/drm_dumb_buffers.c
+++ b/drivers/gpu/drm/drm_dumb_buffers.c
@@ -25,6 +25,8 @@
 
 #include <drm/drm_device.h>
 #include <drm/drm_drv.h>
+#include <drm/drm_dumb_buffers.h>
+#include <drm/drm_fourcc.h>
 #include <drm/drm_gem.h>
 #include <drm/drm_mode.h>
 
@@ -57,6 +59,136 @@
  * a hardware-specific ioctl to allocate suitable buffer objects.
  */
 
+static int drm_mode_align_dumb(struct drm_mode_create_dumb *args,
+			       unsigned long hw_pitch_align,
+			       unsigned long hw_size_align)
+{
+	u32 pitch = args->pitch;
+	u32 size;
+
+	if (!pitch)
+		return -EINVAL;
+
+	if (hw_pitch_align)
+		pitch = roundup(pitch, hw_pitch_align);
+
+	/* overflow checks for 32bit size calculations */
+	if (args->height > U32_MAX / pitch)
+		return -EINVAL;
+
+	if (!hw_size_align)
+		hw_size_align = PAGE_SIZE;
+	else if (!IS_ALIGNED(hw_size_align, PAGE_SIZE))
+		return -EINVAL; /* TODO: handle this if necessary */
+
+	size = ALIGN(args->height * pitch, hw_size_align);
+	if (!size)
+		return -EINVAL;
+
+	args->pitch = pitch;
+	args->size = size;
+
+	return 0;
+}
+
+/**
+ * drm_mode_size_dumb - Calculates the scanline and buffer sizes for dumb buffers
+ * @dev: DRM device
+ * @args: Parameters for the dumb buffer
+ * @hw_pitch_align: Hardware scanline alignment in bytes
+ * @hw_size_align: Hardware buffer-size alignment in bytes
+ *
+ * The helper drm_mode_size_dumb() calculates the size of the buffer
+ * allocation and the scanline size for a dumb buffer. Callers have to
+ * set the buffers width, height and color mode in the argument @arg.
+ * The helper validates the correctness of the input and tests for
+ * possible overflows. If successful, it returns the dumb buffer's
+ * required scanline pitch and size in &args.
+ *
+ * The parameter @hw_pitch_align allows the driver to specifies an
+ * alignment for the scanline pitch, if the hardware requires any. The
+ * calculated pitch will be a multiple of the alignment. The parameter
+ * @hw_size_align allows to specify an alignment for buffer sizes. The
+ * provided alignment should represent requirements of the graphics
+ * hardware. drm_mode_size_dumb() handles GEM-related constraints
+ * automatically across all drivers and hardware. For example, the
+ * returned buffer size is always a multiple of PAGE_SIZE, which is
+ * required by mmap().
+ *
+ * Returns:
+ * Zero on success, or a negative error code otherwise.
+ */
+int drm_mode_size_dumb(struct drm_device *dev,
+		       struct drm_mode_create_dumb *args,
+		       unsigned long hw_pitch_align,
+		       unsigned long hw_size_align)
+{
+	u64 pitch = 0;
+	u32 fourcc;
+
+	/*
+	 * The scanline pitch depends on the buffer width and the color
+	 * format. The latter is specified as a color-mode constant for
+	 * which we first have to find the corresponding color format.
+	 *
+	 * Different color formats can have the same color-mode constant.
+	 * For example XRGB8888 and BGRX8888 both have a color mode of 32.
+	 * It is possible to use different formats for dumb-buffer allocation
+	 * and rendering as long as all involved formats share the same
+	 * color-mode constant.
+	 */
+	fourcc = drm_driver_color_mode_format(dev, args->bpp);
+	if (fourcc != DRM_FORMAT_INVALID) {
+		const struct drm_format_info *info = drm_format_info(fourcc);
+
+		if (!info)
+			return -EINVAL;
+		pitch = drm_format_info_min_pitch(info, 0, args->width);
+	} else if (args->bpp) {
+		/*
+		 * Some userspace throws in arbitrary values for bpp and
+		 * relies on the kernel to figure it out. In this case we
+		 * fall back to the old method of using bpp directly. The
+		 * over-commitment of memory from the rounding is acceptable
+		 * for compatibility with legacy userspace. We have a number
+		 * of deprecated legacy values that are explicitly supported.
+		 */
+		switch (args->bpp) {
+		default:
+			drm_warn_once(dev,
+				      "Unknown color mode %u; guessing buffer size.\n",
+				      args->bpp);
+			fallthrough;
+		/*
+		 * These constants represent various YUV formats supported by
+		 * drm_gem_afbc_get_bpp().
+		 */
+		case 12: // DRM_FORMAT_YUV420_8BIT
+		case 15: // DRM_FORMAT_YUV420_10BIT
+		case 30: // DRM_FORMAT_VUY101010
+			fallthrough;
+		/*
+		 * Used by Mesa and Gstreamer to allocate NV formats and others
+		 * as RGB buffers. Technically, XRGB16161616F formats are RGB,
+		 * but the dumb buffers are not supposed to be used for anything
+		 * beyond 32 bits per pixels.
+		 */
+		case 10: // DRM_FORMAT_NV{15,20,30}, DRM_FORMAT_P010
+		case 64: // DRM_FORMAT_{XRGB,XBGR,ARGB,ABGR}16161616F
+			pitch = args->width * DIV_ROUND_UP(args->bpp, SZ_8);
+			break;
+		}
+	}
+
+	if (!pitch || pitch > U32_MAX)
+		return -EINVAL;
+
+	args->pitch = pitch;
+
+	return drm_mode_align_dumb(args, hw_pitch_align, hw_size_align);
+}
+EXPORT_SYMBOL(drm_mode_size_dumb);
+
 int drm_mode_create_dumb(struct drm_device *dev,
 			 struct drm_mode_create_dumb *args,
 			 struct drm_file *file_priv)
diff --git a/include/drm/drm_dumb_buffers.h b/include/drm/drm_dumb_buffers.h
new file mode 100644
index 000000000000..1f3a8236fb3d
--- /dev/null
+++ b/include/drm/drm_dumb_buffers.h
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: MIT */
+
+#ifndef __DRM_DUMB_BUFFERS_H__
+#define __DRM_DUMB_BUFFERS_H__
+
+struct drm_device;
+struct drm_mode_create_dumb;
+
+int drm_mode_size_dumb(struct drm_device *dev,
+		       struct drm_mode_create_dumb *args,
+		       unsigned long hw_pitch_align,
+		       unsigned long hw_size_align);
+
+#endif
diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h
index c082810c08a8..efe8f5ad35ee 100644
--- a/include/uapi/drm/drm_mode.h
+++ b/include/uapi/drm/drm_mode.h
@@ -1058,7 +1058,7 @@ struct drm_mode_crtc_page_flip_target {
  * struct drm_mode_create_dumb - Create a KMS dumb buffer for scanout.
  * @height: buffer height in pixels
  * @width: buffer width in pixels
- * @bpp: bits per pixel
+ * @bpp: color mode
  * @flags: must be zero
  * @handle: buffer object handle
  * @pitch: number of bytes between two consecutive lines
@@ -1066,6 +1066,54 @@ struct drm_mode_crtc_page_flip_target {
  *
  * User-space fills @height, @width, @bpp and @flags. If the IOCTL succeeds,
  * the kernel fills @handle, @pitch and @size.
+ *
+ * The value of @bpp is a color-mode number describing a specific format
+ * or a variant thereof. The value often corresponds to the number of bits
+ * per pixel for most modes, although there are exceptions. Each color mode
+ * maps to a DRM format plus a number of modes with similar pixel layout.
+ * Framebuffer layout is always linear.
+ *
+ * Support for all modes and formats is optional. Even if dumb-buffer
+ * creation with a certain color mode succeeds, it is not guaranteed that
+ * the DRM driver supports any of the related formats. Most drivers support
+ * a color mode of 32 with a format of DRM_FORMAT_XRGB8888 on their primary
+ * plane.
+ *
+ * +------------+------------------------+------------------------+
+ * | Color mode | Framebuffer format     | Compatible formats     |
+ * +============+========================+========================+
+ * |     32     |  * DRM_FORMAT_XRGB8888 |  * DRM_FORMAT_BGRX8888 |
+ * |            |                        |  * DRM_FORMAT_RGBX8888 |
+ * |            |                        |  * DRM_FORMAT_XBGR8888 |
+ * +------------+------------------------+------------------------+
+ * |     24     |  * DRM_FORMAT_RGB888   |  * DRM_FORMAT_BGR888   |
+ * +------------+------------------------+------------------------+
+ * |     16     |  * DRM_FORMAT_RGB565   |  * DRM_FORMAT_BGR565   |
+ * +------------+------------------------+------------------------+
+ * |     15     |  * DRM_FORMAT_XRGB1555 |  * DRM_FORMAT_BGRX1555 |
+ * |            |                        |  * DRM_FORMAT_RGBX1555 |
+ * |            |                        |  * DRM_FORMAT_XBGR1555 |
+ * +------------+------------------------+------------------------+
+ * |      8     |  * DRM_FORMAT_C8       |  * DRM_FORMAT_D8       |
+ * |            |                        |  * DRM_FORMAT_R8       |
+ * +------------+------------------------+------------------------+
+ * |      4     |  * DRM_FORMAT_C4       |  * DRM_FORMAT_D4       |
+ * |            |                        |  * DRM_FORMAT_R4       |
+ * +------------+------------------------+------------------------+
+ * |      2     |  * DRM_FORMAT_C2       |  * DRM_FORMAT_D2       |
+ * |            |                        |  * DRM_FORMAT_R2       |
+ * +------------+------------------------+------------------------+
+ * |      1     |  * DRM_FORMAT_C1       |  * DRM_FORMAT_D1       |
+ * |            |                        |  * DRM_FORMAT_R1       |
+ * +------------+------------------------+------------------------+
+ *
+ * Color modes of 10, 12, 15, 30 and 64 are only supported for use by
+ * legacy user space. Please don't use them in new code. Other modes
+ * are not support.
+ *
+ * Do not attempt to allocate anything but linear framebuffer memory
+ * with single-plane RGB data. Allocation of other framebuffer
+ * layouts requires dedicated ioctls in the respective DRM driver.
  */
 struct drm_mode_create_dumb {
 	__u32 height;
-- 
2.48.1

Re: [PATCH v4 02/25] drm/dumb-buffers: Provide helper to set pitch and size

[Tomi Valkeinen]

Hi,

On 11/03/2025 17:47, Thomas Zimmermann wrote:
> Add drm_modes_size_dumb(), a helper to calculate the dumb-buffer
> scanline pitch and allocation size. Implementations of struct
> drm_driver.dumb_create can call the new helper for their size
> computations.
> 
> There is currently quite a bit of code duplication among DRM's
> memory managers. Each calculates scanline pitch and buffer size
> from the given arguments, but the implementations are inconsistent
> in how they treat alignment and format support. Later patches will
> unify this code on top of drm_mode_size_dumb() as much as possible.
> 
> drm_mode_size_dumb() uses existing 4CC format helpers to interpret
> the given color mode. This makes the dumb-buffer interface behave
> similar the kernel's video= parameter. Current per-driver implementations
> again likely have subtle differences or bugs in how they support color
> modes.
> 
> The dumb-buffer UAPI is only specified for known color modes. These
> values describe linear, single-plane RGB color formats or legacy index
> formats. Other values should not be specified. But some user space
> still does. So for unknown color modes, there are a number of known
> exceptions for which drm_mode_size_dumb() calculates the pitch from
> the bpp value, as before. All other values work the same but print
> an error.
> 
> v4:
> - use %u conversion specifier (Geert)
> - list DRM_FORMAT_Dn in UAPI docs (Geert)
> - avoid dmesg spamming with drm_warn_once() (Sima)
> - add more information about bpp special case (Sima)
> - clarify parameters for hardware alignment
> - add a TODO item for DUMB_CREATE2
> v3:
> - document the UAPI semantics
> - compute scanline pitch from for unknown color modes (Andy, Tomi)
> 
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> ---
>  Documentation/gpu/todo.rst         |  28 ++++++
>  drivers/gpu/drm/drm_dumb_buffers.c | 132 +++++++++++++++++++++++++++++
>  include/drm/drm_dumb_buffers.h     |  14 +++
>  include/uapi/drm/drm_mode.h        |  50 ++++++++++-
>  4 files changed, 223 insertions(+), 1 deletion(-)
>  create mode 100644 include/drm/drm_dumb_buffers.h
> 
> diff --git a/Documentation/gpu/todo.rst b/Documentation/gpu/todo.rst
> index c57777a24e03..f1bd741b06dc 100644
> --- a/Documentation/gpu/todo.rst
> +++ b/Documentation/gpu/todo.rst
> @@ -515,6 +515,34 @@ Contact: Douglas Anderson <dianders@chromium.org>
>  
>  Level: Starter
>  
> +Implement a new DUMB_CREATE2 ioctl
> +----------------------------------
> +
> +The current DUMB_CREATE ioctl is not well defined. Instead of a pixel and
> +framebuffer format, it only accepts a color mode of vague semantics. Assuming
> +a linear framebuffer, the color mode gives and idea of the supported pixel
> +format. But userspace effectively has to guess the correct values. It really
> +only works reliable with framebuffers in XRGB8888. Userspace has begun to
> +workaround these limitations by computing arbitrary format's buffer sizes and
> +calculating their sizes in terms of XRGB8888 pixels.
> +
> +One possible solution is a new ioctl DUMB_CREATE2. It should accept a DRM
> +format and a format modifier to resolve the color mode's ambiguity. As
> +framebuffers can be multi-planar, the new ioctl has to return the buffer size,
> +pitch and GEM handle for each individual color plane.
> +
> +In the first step, the new ioctl can be limited to the current features of
> +the existing DUMB_CREATE. Individual drivers can then be extended to support
> +multi-planar formats. Rockchip might require this and would be a good candidate.
> +
> +In addition to the kernel implementation, there must be user-space support
> +for the new ioctl. There's code in Mesa that might be able to use the new
> +call.
> +
> +Contact: Thomas Zimmermann <tzimmermann@suse.de>
> +
> +Level: Advanced
> +
>  
>  Core refactorings
>  =================
> diff --git a/drivers/gpu/drm/drm_dumb_buffers.c b/drivers/gpu/drm/drm_dumb_buffers.c
> index 9916aaf5b3f2..97cd3dcb79f1 100644
> --- a/drivers/gpu/drm/drm_dumb_buffers.c
> +++ b/drivers/gpu/drm/drm_dumb_buffers.c
> @@ -25,6 +25,8 @@
>  
>  #include <drm/drm_device.h>
>  #include <drm/drm_drv.h>
> +#include <drm/drm_dumb_buffers.h>
> +#include <drm/drm_fourcc.h>
>  #include <drm/drm_gem.h>
>  #include <drm/drm_mode.h>
>  
> @@ -57,6 +59,136 @@
>   * a hardware-specific ioctl to allocate suitable buffer objects.
>   */
>  
> +static int drm_mode_align_dumb(struct drm_mode_create_dumb *args,
> +			       unsigned long hw_pitch_align,
> +			       unsigned long hw_size_align)
> +{
> +	u32 pitch = args->pitch;
> +	u32 size;
> +
> +	if (!pitch)
> +		return -EINVAL;
> +
> +	if (hw_pitch_align)
> +		pitch = roundup(pitch, hw_pitch_align);
> +
> +	/* overflow checks for 32bit size calculations */
> +	if (args->height > U32_MAX / pitch)
> +		return -EINVAL;
> +

check_mul_overflow(args->height, pitch, &size)?

> +	if (!hw_size_align)
> +		hw_size_align = PAGE_SIZE;
> +	else if (!IS_ALIGNED(hw_size_align, PAGE_SIZE))
> +		return -EINVAL; /* TODO: handle this if necessary */
> +
> +	size = ALIGN(args->height * pitch, hw_size_align);
> +	if (!size)
> +		return -EINVAL;
> +
> +	args->pitch = pitch;
> +	args->size = size;
> +
> +	return 0;
> +}
> +
> +/**
> + * drm_mode_size_dumb - Calculates the scanline and buffer sizes for dumb buffers
> + * @dev: DRM device
> + * @args: Parameters for the dumb buffer
> + * @hw_pitch_align: Hardware scanline alignment in bytes
> + * @hw_size_align: Hardware buffer-size alignment in bytes
> + *
> + * The helper drm_mode_size_dumb() calculates the size of the buffer
> + * allocation and the scanline size for a dumb buffer. Callers have to
> + * set the buffers width, height and color mode in the argument @arg.
> + * The helper validates the correctness of the input and tests for
> + * possible overflows. If successful, it returns the dumb buffer's
> + * required scanline pitch and size in &args.
> + *
> + * The parameter @hw_pitch_align allows the driver to specifies an
> + * alignment for the scanline pitch, if the hardware requires any. The
> + * calculated pitch will be a multiple of the alignment. The parameter
> + * @hw_size_align allows to specify an alignment for buffer sizes. The
> + * provided alignment should represent requirements of the graphics
> + * hardware. drm_mode_size_dumb() handles GEM-related constraints
> + * automatically across all drivers and hardware. For example, the
> + * returned buffer size is always a multiple of PAGE_SIZE, which is
> + * required by mmap().
> + *
> + * Returns:
> + * Zero on success, or a negative error code otherwise.
> + */
> +int drm_mode_size_dumb(struct drm_device *dev,
> +		       struct drm_mode_create_dumb *args,
> +		       unsigned long hw_pitch_align,
> +		       unsigned long hw_size_align)
> +{
> +	u64 pitch = 0;
> +	u32 fourcc;
> +
> +	/*
> +	 * The scanline pitch depends on the buffer width and the color
> +	 * format. The latter is specified as a color-mode constant for
> +	 * which we first have to find the corresponding color format.
> +	 *
> +	 * Different color formats can have the same color-mode constant.
> +	 * For example XRGB8888 and BGRX8888 both have a color mode of 32.
> +	 * It is possible to use different formats for dumb-buffer allocation
> +	 * and rendering as long as all involved formats share the same
> +	 * color-mode constant.
> +	 */
> +	fourcc = drm_driver_color_mode_format(dev, args->bpp);
> +	if (fourcc != DRM_FORMAT_INVALID) {
> +		const struct drm_format_info *info = drm_format_info(fourcc);
> +
> +		if (!info)
> +			return -EINVAL;
> +		pitch = drm_format_info_min_pitch(info, 0, args->width);
> +	} else if (args->bpp) {
> +		/*
> +		 * Some userspace throws in arbitrary values for bpp and
> +		 * relies on the kernel to figure it out. In this case we
> +		 * fall back to the old method of using bpp directly. The
> +		 * over-commitment of memory from the rounding is acceptable
> +		 * for compatibility with legacy userspace. We have a number
> +		 * of deprecated legacy values that are explicitly supported.
> +		 */
> +		switch (args->bpp) {
> +		default:
> +			drm_warn_once(dev,
> +				      "Unknown color mode %u; guessing buffer size.\n",
> +				      args->bpp);
> +			fallthrough;
> +		/*
> +		 * These constants represent various YUV formats supported by
> +		 * drm_gem_afbc_get_bpp().
> +		 */
> +		case 12: // DRM_FORMAT_YUV420_8BIT
> +		case 15: // DRM_FORMAT_YUV420_10BIT
> +		case 30: // DRM_FORMAT_VUY101010
> +			fallthrough;
> +		/*
> +		 * Used by Mesa and Gstreamer to allocate NV formats and others
> +		 * as RGB buffers. Technically, XRGB16161616F formats are RGB,
> +		 * but the dumb buffers are not supposed to be used for anything
> +		 * beyond 32 bits per pixels.
> +		 */
> +		case 10: // DRM_FORMAT_NV{15,20,30}, DRM_FORMAT_P010
> +		case 64: // DRM_FORMAT_{XRGB,XBGR,ARGB,ABGR}16161616F
> +			pitch = args->width * DIV_ROUND_UP(args->bpp, SZ_8);
> +			break;
> +		}
> +	}
> +
> +	if (!pitch || pitch > U32_MAX)
> +		return -EINVAL;
> +
> +	args->pitch = pitch;
> +
> +	return drm_mode_align_dumb(args, hw_pitch_align, hw_size_align);
> +}
> +EXPORT_SYMBOL(drm_mode_size_dumb);
> +
>  int drm_mode_create_dumb(struct drm_device *dev,
>  			 struct drm_mode_create_dumb *args,
>  			 struct drm_file *file_priv)
> diff --git a/include/drm/drm_dumb_buffers.h b/include/drm/drm_dumb_buffers.h
> new file mode 100644
> index 000000000000..1f3a8236fb3d
> --- /dev/null
> +++ b/include/drm/drm_dumb_buffers.h
> @@ -0,0 +1,14 @@
> +/* SPDX-License-Identifier: MIT */
> +
> +#ifndef __DRM_DUMB_BUFFERS_H__
> +#define __DRM_DUMB_BUFFERS_H__
> +
> +struct drm_device;
> +struct drm_mode_create_dumb;
> +
> +int drm_mode_size_dumb(struct drm_device *dev,
> +		       struct drm_mode_create_dumb *args,
> +		       unsigned long hw_pitch_align,
> +		       unsigned long hw_size_align);
> +
> +#endif
> diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h
> index c082810c08a8..efe8f5ad35ee 100644
> --- a/include/uapi/drm/drm_mode.h
> +++ b/include/uapi/drm/drm_mode.h
> @@ -1058,7 +1058,7 @@ struct drm_mode_crtc_page_flip_target {
>   * struct drm_mode_create_dumb - Create a KMS dumb buffer for scanout.
>   * @height: buffer height in pixels
>   * @width: buffer width in pixels
> - * @bpp: bits per pixel
> + * @bpp: color mode
>   * @flags: must be zero
>   * @handle: buffer object handle
>   * @pitch: number of bytes between two consecutive lines
> @@ -1066,6 +1066,54 @@ struct drm_mode_crtc_page_flip_target {
>   *
>   * User-space fills @height, @width, @bpp and @flags. If the IOCTL succeeds,
>   * the kernel fills @handle, @pitch and @size.
> + *
> + * The value of @bpp is a color-mode number describing a specific format
> + * or a variant thereof. The value often corresponds to the number of bits
> + * per pixel for most modes, although there are exceptions. Each color mode
> + * maps to a DRM format plus a number of modes with similar pixel layout.
> + * Framebuffer layout is always linear.
> + *
> + * Support for all modes and formats is optional. Even if dumb-buffer
> + * creation with a certain color mode succeeds, it is not guaranteed that
> + * the DRM driver supports any of the related formats. Most drivers support
> + * a color mode of 32 with a format of DRM_FORMAT_XRGB8888 on their primary
> + * plane.
> + *
> + * +------------+------------------------+------------------------+
> + * | Color mode | Framebuffer format     | Compatible formats     |
> + * +============+========================+========================+
> + * |     32     |  * DRM_FORMAT_XRGB8888 |  * DRM_FORMAT_BGRX8888 |
> + * |            |                        |  * DRM_FORMAT_RGBX8888 |
> + * |            |                        |  * DRM_FORMAT_XBGR8888 |
> + * +------------+------------------------+------------------------+
> + * |     24     |  * DRM_FORMAT_RGB888   |  * DRM_FORMAT_BGR888   |
> + * +------------+------------------------+------------------------+
> + * |     16     |  * DRM_FORMAT_RGB565   |  * DRM_FORMAT_BGR565   |
> + * +------------+------------------------+------------------------+
> + * |     15     |  * DRM_FORMAT_XRGB1555 |  * DRM_FORMAT_BGRX1555 |
> + * |            |                        |  * DRM_FORMAT_RGBX1555 |
> + * |            |                        |  * DRM_FORMAT_XBGR1555 |
> + * +------------+------------------------+------------------------+
> + * |      8     |  * DRM_FORMAT_C8       |  * DRM_FORMAT_D8       |
> + * |            |                        |  * DRM_FORMAT_R8       |
> + * +------------+------------------------+------------------------+
> + * |      4     |  * DRM_FORMAT_C4       |  * DRM_FORMAT_D4       |
> + * |            |                        |  * DRM_FORMAT_R4       |
> + * +------------+------------------------+------------------------+
> + * |      2     |  * DRM_FORMAT_C2       |  * DRM_FORMAT_D2       |
> + * |            |                        |  * DRM_FORMAT_R2       |
> + * +------------+------------------------+------------------------+
> + * |      1     |  * DRM_FORMAT_C1       |  * DRM_FORMAT_D1       |
> + * |            |                        |  * DRM_FORMAT_R1       |
> + * +------------+------------------------+------------------------+
> + *
> + * Color modes of 10, 12, 15, 30 and 64 are only supported for use by
> + * legacy user space. Please don't use them in new code. Other modes
> + * are not support.
> + *
> + * Do not attempt to allocate anything but linear framebuffer memory
> + * with single-plane RGB data. Allocation of other framebuffer
> + * layouts requires dedicated ioctls in the respective DRM driver.
>   */
>  struct drm_mode_create_dumb {
>  	__u32 height;

Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>

 Tomi

Re: [PATCH v4 02/25] drm/dumb-buffers: Provide helper to set pitch and size

[Thomas Zimmermann]

Hi

Am 12.06.25 um 10:36 schrieb Tomi Valkeinen:
> Hi,
>
> On 11/03/2025 17:47, Thomas Zimmermann wrote:
>> Add drm_modes_size_dumb(), a helper to calculate the dumb-buffer
>> scanline pitch and allocation size. Implementations of struct
>> drm_driver.dumb_create can call the new helper for their size
>> computations.
>>
>> There is currently quite a bit of code duplication among DRM's
>> memory managers. Each calculates scanline pitch and buffer size
>> from the given arguments, but the implementations are inconsistent
>> in how they treat alignment and format support. Later patches will
>> unify this code on top of drm_mode_size_dumb() as much as possible.
>>
>> drm_mode_size_dumb() uses existing 4CC format helpers to interpret
>> the given color mode. This makes the dumb-buffer interface behave
>> similar the kernel's video= parameter. Current per-driver implementations
>> again likely have subtle differences or bugs in how they support color
>> modes.
>>
>> The dumb-buffer UAPI is only specified for known color modes. These
>> values describe linear, single-plane RGB color formats or legacy index
>> formats. Other values should not be specified. But some user space
>> still does. So for unknown color modes, there are a number of known
>> exceptions for which drm_mode_size_dumb() calculates the pitch from
>> the bpp value, as before. All other values work the same but print
>> an error.
>>
>> v4:
>> - use %u conversion specifier (Geert)
>> - list DRM_FORMAT_Dn in UAPI docs (Geert)
>> - avoid dmesg spamming with drm_warn_once() (Sima)
>> - add more information about bpp special case (Sima)
>> - clarify parameters for hardware alignment
>> - add a TODO item for DUMB_CREATE2
>> v3:
>> - document the UAPI semantics
>> - compute scanline pitch from for unknown color modes (Andy, Tomi)
>>
>> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
>> ---
>>   Documentation/gpu/todo.rst         |  28 ++++++
>>   drivers/gpu/drm/drm_dumb_buffers.c | 132 +++++++++++++++++++++++++++++
>>   include/drm/drm_dumb_buffers.h     |  14 +++
>>   include/uapi/drm/drm_mode.h        |  50 ++++++++++-
>>   4 files changed, 223 insertions(+), 1 deletion(-)
>>   create mode 100644 include/drm/drm_dumb_buffers.h
>>
>> diff --git a/Documentation/gpu/todo.rst b/Documentation/gpu/todo.rst
>> index c57777a24e03..f1bd741b06dc 100644
>> --- a/Documentation/gpu/todo.rst
>> +++ b/Documentation/gpu/todo.rst
>> @@ -515,6 +515,34 @@ Contact: Douglas Anderson <dianders@chromium.org>
>>   
>>   Level: Starter
>>   
>> +Implement a new DUMB_CREATE2 ioctl
>> +----------------------------------
>> +
>> +The current DUMB_CREATE ioctl is not well defined. Instead of a pixel and
>> +framebuffer format, it only accepts a color mode of vague semantics. Assuming
>> +a linear framebuffer, the color mode gives and idea of the supported pixel
>> +format. But userspace effectively has to guess the correct values. It really
>> +only works reliable with framebuffers in XRGB8888. Userspace has begun to
>> +workaround these limitations by computing arbitrary format's buffer sizes and
>> +calculating their sizes in terms of XRGB8888 pixels.
>> +
>> +One possible solution is a new ioctl DUMB_CREATE2. It should accept a DRM
>> +format and a format modifier to resolve the color mode's ambiguity. As
>> +framebuffers can be multi-planar, the new ioctl has to return the buffer size,
>> +pitch and GEM handle for each individual color plane.
>> +
>> +In the first step, the new ioctl can be limited to the current features of
>> +the existing DUMB_CREATE. Individual drivers can then be extended to support
>> +multi-planar formats. Rockchip might require this and would be a good candidate.
>> +
>> +In addition to the kernel implementation, there must be user-space support
>> +for the new ioctl. There's code in Mesa that might be able to use the new
>> +call.
>> +
>> +Contact: Thomas Zimmermann <tzimmermann@suse.de>
>> +
>> +Level: Advanced
>> +
>>   
>>   Core refactorings
>>   =================
>> diff --git a/drivers/gpu/drm/drm_dumb_buffers.c b/drivers/gpu/drm/drm_dumb_buffers.c
>> index 9916aaf5b3f2..97cd3dcb79f1 100644
>> --- a/drivers/gpu/drm/drm_dumb_buffers.c
>> +++ b/drivers/gpu/drm/drm_dumb_buffers.c
>> @@ -25,6 +25,8 @@
>>   
>>   #include <drm/drm_device.h>
>>   #include <drm/drm_drv.h>
>> +#include <drm/drm_dumb_buffers.h>
>> +#include <drm/drm_fourcc.h>
>>   #include <drm/drm_gem.h>
>>   #include <drm/drm_mode.h>
>>   
>> @@ -57,6 +59,136 @@
>>    * a hardware-specific ioctl to allocate suitable buffer objects.
>>    */
>>   
>> +static int drm_mode_align_dumb(struct drm_mode_create_dumb *args,
>> +			       unsigned long hw_pitch_align,
>> +			       unsigned long hw_size_align)
>> +{
>> +	u32 pitch = args->pitch;
>> +	u32 size;
>> +
>> +	if (!pitch)
>> +		return -EINVAL;
>> +
>> +	if (hw_pitch_align)
>> +		pitch = roundup(pitch, hw_pitch_align);
>> +
>> +	/* overflow checks for 32bit size calculations */
>> +	if (args->height > U32_MAX / pitch)
>> +		return -EINVAL;
>> +
> check_mul_overflow(args->height, pitch, &size)?

I wasn't aware of that. Requires some re-arrangement of the code, but 
probably makes sense.

>
>> +	if (!hw_size_align)
>> +		hw_size_align = PAGE_SIZE;
>> +	else if (!IS_ALIGNED(hw_size_align, PAGE_SIZE))
>> +		return -EINVAL; /* TODO: handle this if necessary */
>> +
>> +	size = ALIGN(args->height * pitch, hw_size_align);
>> +	if (!size)
>> +		return -EINVAL;
>> +
>> +	args->pitch = pitch;
>> +	args->size = size;
>> +
>> +	return 0;
>> +}
>> +
>> +/**
>> + * drm_mode_size_dumb - Calculates the scanline and buffer sizes for dumb buffers
>> + * @dev: DRM device
>> + * @args: Parameters for the dumb buffer
>> + * @hw_pitch_align: Hardware scanline alignment in bytes
>> + * @hw_size_align: Hardware buffer-size alignment in bytes
>> + *
>> + * The helper drm_mode_size_dumb() calculates the size of the buffer
>> + * allocation and the scanline size for a dumb buffer. Callers have to
>> + * set the buffers width, height and color mode in the argument @arg.
>> + * The helper validates the correctness of the input and tests for
>> + * possible overflows. If successful, it returns the dumb buffer's
>> + * required scanline pitch and size in &args.
>> + *
>> + * The parameter @hw_pitch_align allows the driver to specifies an
>> + * alignment for the scanline pitch, if the hardware requires any. The
>> + * calculated pitch will be a multiple of the alignment. The parameter
>> + * @hw_size_align allows to specify an alignment for buffer sizes. The
>> + * provided alignment should represent requirements of the graphics
>> + * hardware. drm_mode_size_dumb() handles GEM-related constraints
>> + * automatically across all drivers and hardware. For example, the
>> + * returned buffer size is always a multiple of PAGE_SIZE, which is
>> + * required by mmap().
>> + *
>> + * Returns:
>> + * Zero on success, or a negative error code otherwise.
>> + */
>> +int drm_mode_size_dumb(struct drm_device *dev,
>> +		       struct drm_mode_create_dumb *args,
>> +		       unsigned long hw_pitch_align,
>> +		       unsigned long hw_size_align)
>> +{
>> +	u64 pitch = 0;
>> +	u32 fourcc;
>> +
>> +	/*
>> +	 * The scanline pitch depends on the buffer width and the color
>> +	 * format. The latter is specified as a color-mode constant for
>> +	 * which we first have to find the corresponding color format.
>> +	 *
>> +	 * Different color formats can have the same color-mode constant.
>> +	 * For example XRGB8888 and BGRX8888 both have a color mode of 32.
>> +	 * It is possible to use different formats for dumb-buffer allocation
>> +	 * and rendering as long as all involved formats share the same
>> +	 * color-mode constant.
>> +	 */
>> +	fourcc = drm_driver_color_mode_format(dev, args->bpp);
>> +	if (fourcc != DRM_FORMAT_INVALID) {
>> +		const struct drm_format_info *info = drm_format_info(fourcc);
>> +
>> +		if (!info)
>> +			return -EINVAL;
>> +		pitch = drm_format_info_min_pitch(info, 0, args->width);
>> +	} else if (args->bpp) {
>> +		/*
>> +		 * Some userspace throws in arbitrary values for bpp and
>> +		 * relies on the kernel to figure it out. In this case we
>> +		 * fall back to the old method of using bpp directly. The
>> +		 * over-commitment of memory from the rounding is acceptable
>> +		 * for compatibility with legacy userspace. We have a number
>> +		 * of deprecated legacy values that are explicitly supported.
>> +		 */
>> +		switch (args->bpp) {
>> +		default:
>> +			drm_warn_once(dev,
>> +				      "Unknown color mode %u; guessing buffer size.\n",
>> +				      args->bpp);
>> +			fallthrough;
>> +		/*
>> +		 * These constants represent various YUV formats supported by
>> +		 * drm_gem_afbc_get_bpp().
>> +		 */
>> +		case 12: // DRM_FORMAT_YUV420_8BIT
>> +		case 15: // DRM_FORMAT_YUV420_10BIT
>> +		case 30: // DRM_FORMAT_VUY101010
>> +			fallthrough;
>> +		/*
>> +		 * Used by Mesa and Gstreamer to allocate NV formats and others
>> +		 * as RGB buffers. Technically, XRGB16161616F formats are RGB,
>> +		 * but the dumb buffers are not supposed to be used for anything
>> +		 * beyond 32 bits per pixels.
>> +		 */
>> +		case 10: // DRM_FORMAT_NV{15,20,30}, DRM_FORMAT_P010
>> +		case 64: // DRM_FORMAT_{XRGB,XBGR,ARGB,ABGR}16161616F
>> +			pitch = args->width * DIV_ROUND_UP(args->bpp, SZ_8);
>> +			break;
>> +		}
>> +	}
>> +
>> +	if (!pitch || pitch > U32_MAX)
>> +		return -EINVAL;
>> +
>> +	args->pitch = pitch;
>> +
>> +	return drm_mode_align_dumb(args, hw_pitch_align, hw_size_align);
>> +}
>> +EXPORT_SYMBOL(drm_mode_size_dumb);
>> +
>>   int drm_mode_create_dumb(struct drm_device *dev,
>>   			 struct drm_mode_create_dumb *args,
>>   			 struct drm_file *file_priv)
>> diff --git a/include/drm/drm_dumb_buffers.h b/include/drm/drm_dumb_buffers.h
>> new file mode 100644
>> index 000000000000..1f3a8236fb3d
>> --- /dev/null
>> +++ b/include/drm/drm_dumb_buffers.h
>> @@ -0,0 +1,14 @@
>> +/* SPDX-License-Identifier: MIT */
>> +
>> +#ifndef __DRM_DUMB_BUFFERS_H__
>> +#define __DRM_DUMB_BUFFERS_H__
>> +
>> +struct drm_device;
>> +struct drm_mode_create_dumb;
>> +
>> +int drm_mode_size_dumb(struct drm_device *dev,
>> +		       struct drm_mode_create_dumb *args,
>> +		       unsigned long hw_pitch_align,
>> +		       unsigned long hw_size_align);
>> +
>> +#endif
>> diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h
>> index c082810c08a8..efe8f5ad35ee 100644
>> --- a/include/uapi/drm/drm_mode.h
>> +++ b/include/uapi/drm/drm_mode.h
>> @@ -1058,7 +1058,7 @@ struct drm_mode_crtc_page_flip_target {
>>    * struct drm_mode_create_dumb - Create a KMS dumb buffer for scanout.
>>    * @height: buffer height in pixels
>>    * @width: buffer width in pixels
>> - * @bpp: bits per pixel
>> + * @bpp: color mode
>>    * @flags: must be zero
>>    * @handle: buffer object handle
>>    * @pitch: number of bytes between two consecutive lines
>> @@ -1066,6 +1066,54 @@ struct drm_mode_crtc_page_flip_target {
>>    *
>>    * User-space fills @height, @width, @bpp and @flags. If the IOCTL succeeds,
>>    * the kernel fills @handle, @pitch and @size.
>> + *
>> + * The value of @bpp is a color-mode number describing a specific format
>> + * or a variant thereof. The value often corresponds to the number of bits
>> + * per pixel for most modes, although there are exceptions. Each color mode
>> + * maps to a DRM format plus a number of modes with similar pixel layout.
>> + * Framebuffer layout is always linear.
>> + *
>> + * Support for all modes and formats is optional. Even if dumb-buffer
>> + * creation with a certain color mode succeeds, it is not guaranteed that
>> + * the DRM driver supports any of the related formats. Most drivers support
>> + * a color mode of 32 with a format of DRM_FORMAT_XRGB8888 on their primary
>> + * plane.
>> + *
>> + * +------------+------------------------+------------------------+
>> + * | Color mode | Framebuffer format     | Compatible formats     |
>> + * +============+========================+========================+
>> + * |     32     |  * DRM_FORMAT_XRGB8888 |  * DRM_FORMAT_BGRX8888 |
>> + * |            |                        |  * DRM_FORMAT_RGBX8888 |
>> + * |            |                        |  * DRM_FORMAT_XBGR8888 |
>> + * +------------+------------------------+------------------------+
>> + * |     24     |  * DRM_FORMAT_RGB888   |  * DRM_FORMAT_BGR888   |
>> + * +------------+------------------------+------------------------+
>> + * |     16     |  * DRM_FORMAT_RGB565   |  * DRM_FORMAT_BGR565   |
>> + * +------------+------------------------+------------------------+
>> + * |     15     |  * DRM_FORMAT_XRGB1555 |  * DRM_FORMAT_BGRX1555 |
>> + * |            |                        |  * DRM_FORMAT_RGBX1555 |
>> + * |            |                        |  * DRM_FORMAT_XBGR1555 |
>> + * +------------+------------------------+------------------------+
>> + * |      8     |  * DRM_FORMAT_C8       |  * DRM_FORMAT_D8       |
>> + * |            |                        |  * DRM_FORMAT_R8       |
>> + * +------------+------------------------+------------------------+
>> + * |      4     |  * DRM_FORMAT_C4       |  * DRM_FORMAT_D4       |
>> + * |            |                        |  * DRM_FORMAT_R4       |
>> + * +------------+------------------------+------------------------+
>> + * |      2     |  * DRM_FORMAT_C2       |  * DRM_FORMAT_D2       |
>> + * |            |                        |  * DRM_FORMAT_R2       |
>> + * +------------+------------------------+------------------------+
>> + * |      1     |  * DRM_FORMAT_C1       |  * DRM_FORMAT_D1       |
>> + * |            |                        |  * DRM_FORMAT_R1       |
>> + * +------------+------------------------+------------------------+
>> + *
>> + * Color modes of 10, 12, 15, 30 and 64 are only supported for use by
>> + * legacy user space. Please don't use them in new code. Other modes
>> + * are not support.
>> + *
>> + * Do not attempt to allocate anything but linear framebuffer memory
>> + * with single-plane RGB data. Allocation of other framebuffer
>> + * layouts requires dedicated ioctls in the respective DRM driver.
>>    */
>>   struct drm_mode_create_dumb {
>>   	__u32 height;
> Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>

Thanks for reviewing.

Best regards
Thomas

>
>   Tomi
>

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)

[PATCH v4 03/25] drm/gem-dma: Compute dumb-buffer sizes with drm_mode_size_dumb()

[Thomas Zimmermann]

Call drm_mode_size_dumb() to compute dumb-buffer scanline pitch and
buffer size. Align the pitch to a multiple of 8.

Push the current calculation into the only direct caller imx. Imx's
hardware requires the framebuffer width to be aligned to 8. The
driver's current approach is actually incorrect, as it only guarantees
this implicitly and requires bpp to be a multiple of 8 already. A
later commit will fix this problem by aligning the scanline pitch
such that an aligned width still fits into each scanline's memory.

A number of other drivers are build on top of gem-dma helpers and
implement their own dumb-buffer allocation. These drivers invoke
drm_gem_dma_dumb_create_internal(), which is not affected by this
commit.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/drm_gem_dma_helper.c     | 7 +++++--
 drivers/gpu/drm/imx/ipuv3/imx-drm-core.c | 2 ++
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_gem_dma_helper.c b/drivers/gpu/drm/drm_gem_dma_helper.c
index b7f033d4352a..49be9b033610 100644
--- a/drivers/gpu/drm/drm_gem_dma_helper.c
+++ b/drivers/gpu/drm/drm_gem_dma_helper.c
@@ -20,6 +20,7 @@
 #include <drm/drm.h>
 #include <drm/drm_device.h>
 #include <drm/drm_drv.h>
+#include <drm/drm_dumb_buffers.h>
 #include <drm/drm_gem_dma_helper.h>
 #include <drm/drm_vma_manager.h>
 
@@ -304,9 +305,11 @@ int drm_gem_dma_dumb_create(struct drm_file *file_priv,
 			    struct drm_mode_create_dumb *args)
 {
 	struct drm_gem_dma_object *dma_obj;
+	int ret;
 
-	args->pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
-	args->size = args->pitch * args->height;
+	ret = drm_mode_size_dumb(drm, args, SZ_8, 0);
+	if (ret)
+		return ret;
 
 	dma_obj = drm_gem_dma_create_with_handle(file_priv, drm, args->size,
 						 &args->handle);
diff --git a/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c b/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c
index ec5fd9a01f1e..e7025df7b978 100644
--- a/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c
+++ b/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c
@@ -145,6 +145,8 @@ static int imx_drm_dumb_create(struct drm_file *file_priv,
 	int ret;
 
 	args->width = ALIGN(width, 8);
+	args->pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
+	args->size = args->pitch * args->height;
 
 	ret = drm_gem_dma_dumb_create(file_priv, drm, args);
 	if (ret)
-- 
2.48.1

Re: [PATCH v4 03/25] drm/gem-dma: Compute dumb-buffer sizes with drm_mode_size_dumb()

[Tomi Valkeinen]

Hi,

On 11/03/2025 17:47, Thomas Zimmermann wrote:
> Call drm_mode_size_dumb() to compute dumb-buffer scanline pitch and
> buffer size. Align the pitch to a multiple of 8.
> 
> Push the current calculation into the only direct caller imx. Imx's
> hardware requires the framebuffer width to be aligned to 8. The
> driver's current approach is actually incorrect, as it only guarantees
> this implicitly and requires bpp to be a multiple of 8 already. A
> later commit will fix this problem by aligning the scanline pitch
> such that an aligned width still fits into each scanline's memory.
> 
> A number of other drivers are build on top of gem-dma helpers and
> implement their own dumb-buffer allocation. These drivers invoke
> drm_gem_dma_dumb_create_internal(), which is not affected by this
> commit.
> 
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> ---
>  drivers/gpu/drm/drm_gem_dma_helper.c     | 7 +++++--
>  drivers/gpu/drm/imx/ipuv3/imx-drm-core.c | 2 ++
>  2 files changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_gem_dma_helper.c b/drivers/gpu/drm/drm_gem_dma_helper.c
> index b7f033d4352a..49be9b033610 100644
> --- a/drivers/gpu/drm/drm_gem_dma_helper.c
> +++ b/drivers/gpu/drm/drm_gem_dma_helper.c
> @@ -20,6 +20,7 @@
>  #include <drm/drm.h>
>  #include <drm/drm_device.h>
>  #include <drm/drm_drv.h>
> +#include <drm/drm_dumb_buffers.h>
>  #include <drm/drm_gem_dma_helper.h>
>  #include <drm/drm_vma_manager.h>
>  
> @@ -304,9 +305,11 @@ int drm_gem_dma_dumb_create(struct drm_file *file_priv,
>  			    struct drm_mode_create_dumb *args)
>  {
>  	struct drm_gem_dma_object *dma_obj;
> +	int ret;
>  
> -	args->pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
> -	args->size = args->pitch * args->height;
> +	ret = drm_mode_size_dumb(drm, args, SZ_8, 0);
> +	if (ret)
> +		return ret;
>  
>  	dma_obj = drm_gem_dma_create_with_handle(file_priv, drm, args->size,
>  						 &args->handle);
> diff --git a/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c b/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c
> index ec5fd9a01f1e..e7025df7b978 100644
> --- a/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c
> +++ b/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c
> @@ -145,6 +145,8 @@ static int imx_drm_dumb_create(struct drm_file *file_priv,
>  	int ret;
>  
>  	args->width = ALIGN(width, 8);
> +	args->pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
> +	args->size = args->pitch * args->height;
>  
>  	ret = drm_gem_dma_dumb_create(file_priv, drm, args);
>  	if (ret)

Won't the pitch and size just be overwritten by the
drm_gem_dma_dumb_create() call?

 Tomi

Re: [PATCH v4 03/25] drm/gem-dma: Compute dumb-buffer sizes with drm_mode_size_dumb()

[Thomas Zimmermann]

Hi

Am 12.06.25 um 10:43 schrieb Tomi Valkeinen:
> Hi,
>
> On 11/03/2025 17:47, Thomas Zimmermann wrote:
>> Call drm_mode_size_dumb() to compute dumb-buffer scanline pitch and
>> buffer size. Align the pitch to a multiple of 8.
>>
>> Push the current calculation into the only direct caller imx. Imx's
>> hardware requires the framebuffer width to be aligned to 8. The
>> driver's current approach is actually incorrect, as it only guarantees
>> this implicitly and requires bpp to be a multiple of 8 already. A
>> later commit will fix this problem by aligning the scanline pitch
>> such that an aligned width still fits into each scanline's memory.
>>
>> A number of other drivers are build on top of gem-dma helpers and
>> implement their own dumb-buffer allocation. These drivers invoke
>> drm_gem_dma_dumb_create_internal(), which is not affected by this
>> commit.
>>
>> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
>> ---
>>   drivers/gpu/drm/drm_gem_dma_helper.c     | 7 +++++--
>>   drivers/gpu/drm/imx/ipuv3/imx-drm-core.c | 2 ++
>>   2 files changed, 7 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_gem_dma_helper.c b/drivers/gpu/drm/drm_gem_dma_helper.c
>> index b7f033d4352a..49be9b033610 100644
>> --- a/drivers/gpu/drm/drm_gem_dma_helper.c
>> +++ b/drivers/gpu/drm/drm_gem_dma_helper.c
>> @@ -20,6 +20,7 @@
>>   #include <drm/drm.h>
>>   #include <drm/drm_device.h>
>>   #include <drm/drm_drv.h>
>> +#include <drm/drm_dumb_buffers.h>
>>   #include <drm/drm_gem_dma_helper.h>
>>   #include <drm/drm_vma_manager.h>
>>   
>> @@ -304,9 +305,11 @@ int drm_gem_dma_dumb_create(struct drm_file *file_priv,
>>   			    struct drm_mode_create_dumb *args)
>>   {
>>   	struct drm_gem_dma_object *dma_obj;
>> +	int ret;
>>   
>> -	args->pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
>> -	args->size = args->pitch * args->height;
>> +	ret = drm_mode_size_dumb(drm, args, SZ_8, 0);
>> +	if (ret)
>> +		return ret;
>>   
>>   	dma_obj = drm_gem_dma_create_with_handle(file_priv, drm, args->size,
>>   						 &args->handle);
>> diff --git a/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c b/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c
>> index ec5fd9a01f1e..e7025df7b978 100644
>> --- a/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c
>> +++ b/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c
>> @@ -145,6 +145,8 @@ static int imx_drm_dumb_create(struct drm_file *file_priv,
>>   	int ret;
>>   
>>   	args->width = ALIGN(width, 8);
>> +	args->pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
>> +	args->size = args->pitch * args->height;
>>   
>>   	ret = drm_gem_dma_dumb_create(file_priv, drm, args);
>>   	if (ret)
> Won't the pitch and size just be overwritten by the
> drm_gem_dma_dumb_create() call?

Right, looks like it. Thanks for looking over this. The call to 
drm_gem_dma_dumb_create() needs to be changed 
drm_gem_dma_dumb_create_internal(). The latter doesn't modify the 
arguments besides some sanity checks. BTW patch 10 cleans up imx 
entirely. Best regards Thomas
>
>   Tomi
>

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)

[PATCH v4 04/25] drm/gem-shmem: Compute dumb-buffer sizes with drm_mode_size_dumb()

[Thomas Zimmermann]

Call drm_mode_size_dumb() to compute dumb-buffer scanline pitch and
buffer size. Align the pitch to a multiple of 8.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/drm_gem_shmem_helper.c | 16 +++++-----------
 1 file changed, 5 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
index d99dee67353a..849ee2cde990 100644
--- a/drivers/gpu/drm/drm_gem_shmem_helper.c
+++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
@@ -18,6 +18,7 @@
 #include <drm/drm.h>
 #include <drm/drm_device.h>
 #include <drm/drm_drv.h>
+#include <drm/drm_dumb_buffers.h>
 #include <drm/drm_gem_shmem_helper.h>
 #include <drm/drm_prime.h>
 #include <drm/drm_print.h>
@@ -514,18 +515,11 @@ EXPORT_SYMBOL(drm_gem_shmem_purge);
 int drm_gem_shmem_dumb_create(struct drm_file *file, struct drm_device *dev,
 			      struct drm_mode_create_dumb *args)
 {
-	u32 min_pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
+	int ret;
 
-	if (!args->pitch || !args->size) {
-		args->pitch = min_pitch;
-		args->size = PAGE_ALIGN(args->pitch * args->height);
-	} else {
-		/* ensure sane minimum values */
-		if (args->pitch < min_pitch)
-			args->pitch = min_pitch;
-		if (args->size < args->pitch * args->height)
-			args->size = PAGE_ALIGN(args->pitch * args->height);
-	}
+	ret = drm_mode_size_dumb(dev, args, SZ_8, 0);
+	if (ret)
+		return ret;
 
 	return drm_gem_shmem_create_with_handle(file, dev, args->size, &args->handle);
 }
-- 
2.48.1

[PATCH v4 05/25] drm/gem-vram: Compute dumb-buffer sizes with drm_mode_size_dumb()

[Thomas Zimmermann]

Call drm_mode_size_dumb() to compute dumb-buffer scanline pitch and
buffer size. Inline code from drm_gem_vram_fill_create_dumb() without
the existing size computation. Align the pitch to a multiple of 8.

Only hibmc and vboxvideo use gem-vram. Hibmc invokes the call to
drm_gem_vram_fill_create_dumb() directly and is therefore not affected.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/drm_gem_vram_helper.c | 24 +++++++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_gem_vram_helper.c b/drivers/gpu/drm/drm_gem_vram_helper.c
index 22b1fe9c03b8..15cd564cbeac 100644
--- a/drivers/gpu/drm/drm_gem_vram_helper.c
+++ b/drivers/gpu/drm/drm_gem_vram_helper.c
@@ -6,6 +6,7 @@
 #include <drm/drm_debugfs.h>
 #include <drm/drm_device.h>
 #include <drm/drm_drv.h>
+#include <drm/drm_dumb_buffers.h>
 #include <drm/drm_file.h>
 #include <drm/drm_framebuffer.h>
 #include <drm/drm_gem_atomic_helper.h>
@@ -582,10 +583,31 @@ int drm_gem_vram_driver_dumb_create(struct drm_file *file,
 				    struct drm_device *dev,
 				    struct drm_mode_create_dumb *args)
 {
+	struct drm_gem_vram_object *gbo;
+	int ret;
+
 	if (WARN_ONCE(!dev->vram_mm, "VRAM MM not initialized"))
 		return -EINVAL;
 
-	return drm_gem_vram_fill_create_dumb(file, dev, 0, 0, args);
+	ret = drm_mode_size_dumb(dev, args, SZ_8, 0);
+	if (ret)
+		return ret;
+
+	gbo = drm_gem_vram_create(dev, args->size, 0);
+	if (IS_ERR(gbo))
+		return PTR_ERR(gbo);
+
+	ret = drm_gem_handle_create(file, &gbo->bo.base, &args->handle);
+	if (ret)
+		goto err_drm_gem_object_put;
+
+	drm_gem_object_put(&gbo->bo.base);
+
+	return 0;
+
+err_drm_gem_object_put:
+	drm_gem_object_put(&gbo->bo.base);
+	return ret;
 }
 EXPORT_SYMBOL(drm_gem_vram_driver_dumb_create);
 
-- 
2.48.1

[PATCH v4 06/25] drm/armada: Compute dumb-buffer sizes with drm_mode_size_dumb()

[Thomas Zimmermann]

Call drm_mode_size_dumb() to compute dumb-buffer scanline pitch and
buffer size. Align the pitch to a multiple of 128.

v4:
- align pitch to 128 bytes (Russell)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Russell King <linux@armlinux.org.uk>
---
 drivers/gpu/drm/armada/armada_gem.c | 16 +++++++---------
 1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/armada/armada_gem.c b/drivers/gpu/drm/armada/armada_gem.c
index 1a1680d71486..a767c4edd5c8 100644
--- a/drivers/gpu/drm/armada/armada_gem.c
+++ b/drivers/gpu/drm/armada/armada_gem.c
@@ -9,6 +9,7 @@
 #include <linux/shmem_fs.h>
 
 #include <drm/armada_drm.h>
+#include <drm/drm_dumb_buffers.h>
 #include <drm/drm_prime.h>
 
 #include "armada_drm.h"
@@ -244,14 +245,13 @@ int armada_gem_dumb_create(struct drm_file *file, struct drm_device *dev,
 	struct drm_mode_create_dumb *args)
 {
 	struct armada_gem_object *dobj;
-	u32 handle;
-	size_t size;
 	int ret;
 
-	args->pitch = armada_pitch(args->width, args->bpp);
-	args->size = size = args->pitch * args->height;
+	ret = drm_mode_size_dumb(dev, args, SZ_128, 0);
+	if (ret)
+		return ret;
 
-	dobj = armada_gem_alloc_private_object(dev, size);
+	dobj = armada_gem_alloc_private_object(dev, args->size);
 	if (dobj == NULL)
 		return -ENOMEM;
 
@@ -259,14 +259,12 @@ int armada_gem_dumb_create(struct drm_file *file, struct drm_device *dev,
 	if (ret)
 		goto err;
 
-	ret = drm_gem_handle_create(file, &dobj->obj, &handle);
+	ret = drm_gem_handle_create(file, &dobj->obj, &args->handle);
 	if (ret)
 		goto err;
 
-	args->handle = handle;
-
 	/* drop reference from allocate - handle holds it now */
-	DRM_DEBUG_DRIVER("obj %p size %zu handle %#x\n", dobj, size, handle);
+	DRM_DEBUG_DRIVER("obj %p size %llu handle %#x\n", dobj, args->size, args->handle);
  err:
 	drm_gem_object_put(&dobj->obj);
 	return ret;
-- 
2.48.1

[PATCH v4 07/25] drm/exynos: Compute dumb-buffer sizes with drm_mode_size_dumb()

[Thomas Zimmermann]

Call drm_mode_size_dumb() to compute dumb-buffer scanline pitch and
buffer size. No alignment required.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Inki Dae <inki.dae@samsung.com>
Cc: Seung-Woo Kim <sw0312.kim@samsung.com>
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Krzysztof Kozlowski <krzk@kernel.org>
Cc: Alim Akhtar <alim.akhtar@samsung.com>
---
 drivers/gpu/drm/exynos/exynos_drm_gem.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/exynos/exynos_drm_gem.c b/drivers/gpu/drm/exynos/exynos_drm_gem.c
index 4787fee4696f..ffa1c02b4b1e 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_gem.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_gem.c
@@ -11,6 +11,7 @@
 #include <linux/shmem_fs.h>
 #include <linux/module.h>
 
+#include <drm/drm_dumb_buffers.h>
 #include <drm/drm_prime.h>
 #include <drm/drm_vma_manager.h>
 #include <drm/exynos_drm.h>
@@ -330,15 +331,16 @@ int exynos_drm_gem_dumb_create(struct drm_file *file_priv,
 	unsigned int flags;
 	int ret;
 
+	ret = drm_mode_size_dumb(dev, args, 0, 0);
+	if (ret)
+		return ret;
+
 	/*
 	 * allocate memory to be used for framebuffer.
 	 * - this callback would be called by user application
 	 *	with DRM_IOCTL_MODE_CREATE_DUMB command.
 	 */
 
-	args->pitch = args->width * ((args->bpp + 7) / 8);
-	args->size = args->pitch * args->height;
-
 	if (is_drm_iommu_supported(dev))
 		flags = EXYNOS_BO_NONCONTIG | EXYNOS_BO_WC;
 	else
-- 
2.48.1

[PATCH v4 08/25] drm/gma500: Compute dumb-buffer sizes with drm_mode_size_dumb()

[Thomas Zimmermann]

Call drm_mode_size_dumb() to compute dumb-buffer scanline pitch and
buffer size. Align the pitch to a multiple of 64.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Patrik Jakobsson <patrik.r.jakobsson@gmail.com>
---
 drivers/gpu/drm/gma500/gem.c | 21 ++++++---------------
 1 file changed, 6 insertions(+), 15 deletions(-)

diff --git a/drivers/gpu/drm/gma500/gem.c b/drivers/gpu/drm/gma500/gem.c
index 4b7627a72637..fc337db0a948 100644
--- a/drivers/gpu/drm/gma500/gem.c
+++ b/drivers/gpu/drm/gma500/gem.c
@@ -16,6 +16,7 @@
 #include <asm/set_memory.h>
 
 #include <drm/drm.h>
+#include <drm/drm_dumb_buffers.h>
 #include <drm/drm_vma_manager.h>
 
 #include "gem.h"
@@ -199,35 +200,25 @@ psb_gem_create(struct drm_device *dev, u64 size, const char *name, bool stolen,
 int psb_gem_dumb_create(struct drm_file *file, struct drm_device *dev,
 			struct drm_mode_create_dumb *args)
 {
-	size_t pitch, size;
 	struct psb_gem_object *pobj;
 	struct drm_gem_object *obj;
-	u32 handle;
 	int ret;
 
-	pitch = args->width * DIV_ROUND_UP(args->bpp, 8);
-	pitch = ALIGN(pitch, 64);
-
-	size = pitch * args->height;
-	size = roundup(size, PAGE_SIZE);
-	if (!size)
-		return -EINVAL;
+	ret = drm_mode_size_dumb(dev, args, SZ_64, 0);
+	if (ret)
+		return ret;
 
-	pobj = psb_gem_create(dev, size, "gem", false, PAGE_SIZE);
+	pobj = psb_gem_create(dev, args->size, "gem", false, PAGE_SIZE);
 	if (IS_ERR(pobj))
 		return PTR_ERR(pobj);
 	obj = &pobj->base;
 
-	ret = drm_gem_handle_create(file, obj, &handle);
+	ret = drm_gem_handle_create(file, obj, &args->handle);
 	if (ret)
 		goto err_drm_gem_object_put;
 
 	drm_gem_object_put(obj);
 
-	args->pitch = pitch;
-	args->size = size;
-	args->handle = handle;
-
 	return 0;
 
 err_drm_gem_object_put:
-- 
2.48.1

[PATCH v4 09/25] drm/hibmc: Compute dumb-buffer sizes with drm_mode_size_dumb()

[Thomas Zimmermann]

Call drm_mode_size_dumb() to compute dumb-buffer scanline pitch and
buffer size. Align the pitch to a multiple of 128.

The hibmc driver's new hibmc_dumb_create() is similar to the one
in GEM VRAM helpers. The driver was the only caller of
drm_gem_vram_fill_create_dumb(). Remove the now unused helper.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Xinliang Liu <xinliang.liu@linaro.org>
Cc: Tian Tao <tiantao6@hisilicon.com>
Cc: Xinwei Kong <kong.kongxinwei@hisilicon.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Yongqin Liu <yongqin.liu@linaro.org>
Cc: John Stultz <jstultz@google.com>
---
 drivers/gpu/drm/drm_gem_vram_helper.c         | 65 -------------------
 .../gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c   | 25 ++++++-
 include/drm/drm_gem_vram_helper.h             |  6 --
 3 files changed, 24 insertions(+), 72 deletions(-)

diff --git a/drivers/gpu/drm/drm_gem_vram_helper.c b/drivers/gpu/drm/drm_gem_vram_helper.c
index 15cd564cbeac..b4cf8134df6d 100644
--- a/drivers/gpu/drm/drm_gem_vram_helper.c
+++ b/drivers/gpu/drm/drm_gem_vram_helper.c
@@ -444,71 +444,6 @@ void drm_gem_vram_vunmap(struct drm_gem_vram_object *gbo,
 }
 EXPORT_SYMBOL(drm_gem_vram_vunmap);
 
-/**
- * drm_gem_vram_fill_create_dumb() - Helper for implementing
- *				     &struct drm_driver.dumb_create
- *
- * @file:		the DRM file
- * @dev:		the DRM device
- * @pg_align:		the buffer's alignment in multiples of the page size
- * @pitch_align:	the scanline's alignment in powers of 2
- * @args:		the arguments as provided to
- *			&struct drm_driver.dumb_create
- *
- * This helper function fills &struct drm_mode_create_dumb, which is used
- * by &struct drm_driver.dumb_create. Implementations of this interface
- * should forwards their arguments to this helper, plus the driver-specific
- * parameters.
- *
- * Returns:
- * 0 on success, or
- * a negative error code otherwise.
- */
-int drm_gem_vram_fill_create_dumb(struct drm_file *file,
-				  struct drm_device *dev,
-				  unsigned long pg_align,
-				  unsigned long pitch_align,
-				  struct drm_mode_create_dumb *args)
-{
-	size_t pitch, size;
-	struct drm_gem_vram_object *gbo;
-	int ret;
-	u32 handle;
-
-	pitch = args->width * DIV_ROUND_UP(args->bpp, 8);
-	if (pitch_align) {
-		if (WARN_ON_ONCE(!is_power_of_2(pitch_align)))
-			return -EINVAL;
-		pitch = ALIGN(pitch, pitch_align);
-	}
-	size = pitch * args->height;
-
-	size = roundup(size, PAGE_SIZE);
-	if (!size)
-		return -EINVAL;
-
-	gbo = drm_gem_vram_create(dev, size, pg_align);
-	if (IS_ERR(gbo))
-		return PTR_ERR(gbo);
-
-	ret = drm_gem_handle_create(file, &gbo->bo.base, &handle);
-	if (ret)
-		goto err_drm_gem_object_put;
-
-	drm_gem_object_put(&gbo->bo.base);
-
-	args->pitch = pitch;
-	args->size = size;
-	args->handle = handle;
-
-	return 0;
-
-err_drm_gem_object_put:
-	drm_gem_object_put(&gbo->bo.base);
-	return ret;
-}
-EXPORT_SYMBOL(drm_gem_vram_fill_create_dumb);
-
 /*
  * Helpers for struct ttm_device_funcs
  */
diff --git a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c
index e6de6d5edf6b..81768577871f 100644
--- a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c
+++ b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c
@@ -18,10 +18,12 @@
 #include <drm/clients/drm_client_setup.h>
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_drv.h>
+#include <drm/drm_dumb_buffers.h>
 #include <drm/drm_fbdev_ttm.h>
 #include <drm/drm_gem_framebuffer_helper.h>
 #include <drm/drm_gem_vram_helper.h>
 #include <drm/drm_managed.h>
+#include <drm/drm_mode.h>
 #include <drm/drm_module.h>
 #include <drm/drm_vblank.h>
 
@@ -54,7 +56,28 @@ static irqreturn_t hibmc_interrupt(int irq, void *arg)
 static int hibmc_dumb_create(struct drm_file *file, struct drm_device *dev,
 			     struct drm_mode_create_dumb *args)
 {
-	return drm_gem_vram_fill_create_dumb(file, dev, 0, 128, args);
+	struct drm_gem_vram_object *gbo;
+	int ret;
+
+	ret = drm_mode_size_dumb(dev, args, SZ_128, 0);
+	if (ret)
+		return ret;
+
+	gbo = drm_gem_vram_create(dev, args->size, 0);
+	if (IS_ERR(gbo))
+		return PTR_ERR(gbo);
+
+	ret = drm_gem_handle_create(file, &gbo->bo.base, &args->handle);
+	if (ret)
+		goto err_drm_gem_object_put;
+
+	drm_gem_object_put(&gbo->bo.base);
+
+	return 0;
+
+err_drm_gem_object_put:
+	drm_gem_object_put(&gbo->bo.base);
+	return ret;
 }
 
 static const struct drm_driver hibmc_driver = {
diff --git a/include/drm/drm_gem_vram_helper.h b/include/drm/drm_gem_vram_helper.h
index 00830b49a3ff..b6e821f5dd03 100644
--- a/include/drm/drm_gem_vram_helper.h
+++ b/include/drm/drm_gem_vram_helper.h
@@ -100,12 +100,6 @@ int drm_gem_vram_vmap(struct drm_gem_vram_object *gbo, struct iosys_map *map);
 void drm_gem_vram_vunmap(struct drm_gem_vram_object *gbo,
 			 struct iosys_map *map);
 
-int drm_gem_vram_fill_create_dumb(struct drm_file *file,
-				  struct drm_device *dev,
-				  unsigned long pg_align,
-				  unsigned long pitch_align,
-				  struct drm_mode_create_dumb *args);
-
 /*
  * Helpers for struct drm_driver
  */
-- 
2.48.1

[PATCH v4 10/25] drm/imx/ipuv3: Compute dumb-buffer sizes with drm_mode_size_dumb()

[Thomas Zimmermann]

Call drm_mode_size_dumb() to compute dumb-buffer scanline pitch and
buffer size. The hardware requires the framebuffer width to be a
multiple of 8. The scanline pitch has be large enough to support
this. Therefore compute the byte size of 8 pixels in the given color
mode and align the pitch accordingly.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Cc: Philipp Zabel <p.zabel@pengutronix.de>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Pengutronix Kernel Team <kernel@pengutronix.de>
Cc: Fabio Estevam <festevam@gmail.com>
---
 drivers/gpu/drm/imx/ipuv3/imx-drm-core.c | 31 ++++++++++++++++++------
 1 file changed, 23 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c b/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c
index e7025df7b978..465b5a6ad5bb 100644
--- a/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c
+++ b/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c
@@ -17,7 +17,9 @@
 #include <drm/drm_atomic.h>
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_drv.h>
+#include <drm/drm_dumb_buffers.h>
 #include <drm/drm_fbdev_dma.h>
+#include <drm/drm_fourcc.h>
 #include <drm/drm_gem_dma_helper.h>
 #include <drm/drm_gem_framebuffer_helper.h>
 #include <drm/drm_managed.h>
@@ -141,19 +143,32 @@ static int imx_drm_dumb_create(struct drm_file *file_priv,
 			       struct drm_device *drm,
 			       struct drm_mode_create_dumb *args)
 {
-	u32 width = args->width;
+	u32 fourcc;
+	const struct drm_format_info *info;
+	u64 pitch_align;
 	int ret;
 
-	args->width = ALIGN(width, 8);
-	args->pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
-	args->size = args->pitch * args->height;
-
-	ret = drm_gem_dma_dumb_create(file_priv, drm, args);
+	/*
+	 * Hardware requires the framebuffer width to be aligned to
+	 * multiples of 8. The mode-setting code handles this, but
+	 * the buffer pitch has to be aligned as well. Set the pitch
+	 * alignment accordingly, so that the each scanline fits into
+	 * the allocated buffer.
+	 */
+	fourcc = drm_driver_color_mode_format(drm, args->bpp);
+	if (fourcc == DRM_FORMAT_INVALID)
+		return -EINVAL;
+	info = drm_format_info(fourcc);
+	if (!info)
+		return -EINVAL;
+	pitch_align = drm_format_info_min_pitch(info, 0, SZ_8);
+	if (!pitch_align || pitch_align > U32_MAX)
+		return -EINVAL;
+	ret = drm_mode_size_dumb(drm, args, pitch_align, 0);
 	if (ret)
 		return ret;
 
-	args->width = width;
-	return ret;
+	return drm_gem_dma_dumb_create(file_priv, drm, args);
 }
 
 static const struct drm_driver imx_drm_driver = {
-- 
2.48.1

[PATCH v4 11/25] drm/loongson: Compute dumb-buffer sizes with drm_mode_size_dumb()

[Thomas Zimmermann]

Call drm_mode_size_dumb() to compute dumb-buffer scanline pitch and
buffer size. Align the pitch according to hardware requirements.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Sui Jingfeng <sui.jingfeng@linux.dev>
Cc: Sui Jingfeng <sui.jingfeng@linux.dev>
---
 drivers/gpu/drm/loongson/lsdc_gem.c | 29 ++++++++---------------------
 1 file changed, 8 insertions(+), 21 deletions(-)

diff --git a/drivers/gpu/drm/loongson/lsdc_gem.c b/drivers/gpu/drm/loongson/lsdc_gem.c
index a720d8f53209..9f982b85301f 100644
--- a/drivers/gpu/drm/loongson/lsdc_gem.c
+++ b/drivers/gpu/drm/loongson/lsdc_gem.c
@@ -6,6 +6,7 @@
 #include <linux/dma-buf.h>
 
 #include <drm/drm_debugfs.h>
+#include <drm/drm_dumb_buffers.h>
 #include <drm/drm_file.h>
 #include <drm/drm_gem.h>
 #include <drm/drm_prime.h>
@@ -204,45 +205,31 @@ int lsdc_dumb_create(struct drm_file *file, struct drm_device *ddev,
 	const struct lsdc_desc *descp = ldev->descp;
 	u32 domain = LSDC_GEM_DOMAIN_VRAM;
 	struct drm_gem_object *gobj;
-	size_t size;
-	u32 pitch;
-	u32 handle;
 	int ret;
 
-	if (!args->width || !args->height)
-		return -EINVAL;
-
-	if (args->bpp != 32 && args->bpp != 16)
-		return -EINVAL;
-
-	pitch = args->width * args->bpp / 8;
-	pitch = ALIGN(pitch, descp->pitch_align);
-	size = pitch * args->height;
-	size = ALIGN(size, PAGE_SIZE);
+	ret = drm_mode_size_dumb(ddev, args, descp->pitch_align, 0);
+	if (ret)
+		return ret;
 
 	/* Maximum single bo size allowed is the half vram size available */
-	if (size > ldev->vram_size / 2) {
-		drm_err(ddev, "Requesting(%zuMiB) failed\n", size >> 20);
+	if (args->size > ldev->vram_size / 2) {
+		drm_err(ddev, "Requesting(%zuMiB) failed\n", (size_t)(args->size >> PAGE_SHIFT));
 		return -ENOMEM;
 	}
 
-	gobj = lsdc_gem_object_create(ddev, domain, size, false, NULL, NULL);
+	gobj = lsdc_gem_object_create(ddev, domain, args->size, false, NULL, NULL);
 	if (IS_ERR(gobj)) {
 		drm_err(ddev, "Failed to create gem object\n");
 		return PTR_ERR(gobj);
 	}
 
-	ret = drm_gem_handle_create(file, gobj, &handle);
+	ret = drm_gem_handle_create(file, gobj, &args->handle);
 
 	/* drop reference from allocate, handle holds it now */
 	drm_gem_object_put(gobj);
 	if (ret)
 		return ret;
 
-	args->pitch = pitch;
-	args->size = size;
-	args->handle = handle;
-
 	return 0;
 }
 
-- 
2.48.1

[PATCH v4 12/25] drm/mediatek: Compute dumb-buffer sizes with drm_mode_size_dumb()

[Thomas Zimmermann]

Call drm_mode_size_dumb() to compute dumb-buffer scanline pitch and
buffer size. Align the pitch to a multiple of 8.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Chun-Kuang Hu <chunkuang.hu@kernel.org>
Cc: Philipp Zabel <p.zabel@pengutronix.de>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Cc: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
---
 drivers/gpu/drm/mediatek/mtk_gem.c | 13 ++++---------
 1 file changed, 4 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_gem.c b/drivers/gpu/drm/mediatek/mtk_gem.c
index a172456d1d7b..21e08fabfd7f 100644
--- a/drivers/gpu/drm/mediatek/mtk_gem.c
+++ b/drivers/gpu/drm/mediatek/mtk_gem.c
@@ -8,6 +8,7 @@
 
 #include <drm/drm.h>
 #include <drm/drm_device.h>
+#include <drm/drm_dumb_buffers.h>
 #include <drm/drm_gem.h>
 #include <drm/drm_gem_dma_helper.h>
 #include <drm/drm_prime.h>
@@ -124,15 +125,9 @@ int mtk_gem_dumb_create(struct drm_file *file_priv, struct drm_device *dev,
 	struct mtk_gem_obj *mtk_gem;
 	int ret;
 
-	args->pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
-
-	/*
-	 * Multiply 2 variables of different types,
-	 * for example: args->size = args->spacing * args->height;
-	 * may cause coverity issue with unintentional overflow.
-	 */
-	args->size = args->pitch;
-	args->size *= args->height;
+	ret = drm_mode_size_dumb(dev, args, SZ_8, 0);
+	if (ret)
+		return ret;
 
 	mtk_gem = mtk_gem_create(dev, args->size, false);
 	if (IS_ERR(mtk_gem))
-- 
2.48.1

[PATCH v4 13/25] drm/msm: Compute dumb-buffer sizes with drm_mode_size_dumb()

[Thomas Zimmermann]

Call drm_mode_size_dumb() to compute dumb-buffer scanline pitch
and buffer size. Alignment is specified in bytes, but the hardware
requires the scanline pitch to be a multiple of 32 pixels. Therefore
compute the byte size of 32 pixels in the given color mode and align
the pitch accordingly. This replaces the existing code in the driver's
align_pitch() helper.

v3:
- clarify pitch alignment in commit message (Dmitry)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Cc: Rob Clark <robdclark@gmail.com>
Cc: Abhinav Kumar <quic_abhinavk@quicinc.com>
Cc: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Cc: Sean Paul <sean@poorly.run>
Cc: Marijn Suijten <marijn.suijten@somainline.org>
---
 drivers/gpu/drm/msm/msm_gem.c | 27 +++++++++++++++++++++++++--
 1 file changed, 25 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c
index ebc9ba66efb8..a956905f1ef2 100644
--- a/drivers/gpu/drm/msm/msm_gem.c
+++ b/drivers/gpu/drm/msm/msm_gem.c
@@ -11,8 +11,10 @@
 #include <linux/dma-buf.h>
 #include <linux/pfn_t.h>
 
+#include <drm/drm_dumb_buffers.h>
 #include <drm/drm_prime.h>
 #include <drm/drm_file.h>
+#include <drm/drm_fourcc.h>
 
 #include <trace/events/gpu_mem.h>
 
@@ -700,8 +702,29 @@ void msm_gem_unpin_iova(struct drm_gem_object *obj,
 int msm_gem_dumb_create(struct drm_file *file, struct drm_device *dev,
 		struct drm_mode_create_dumb *args)
 {
-	args->pitch = align_pitch(args->width, args->bpp);
-	args->size  = PAGE_ALIGN(args->pitch * args->height);
+	u32 fourcc;
+	const struct drm_format_info *info;
+	u64 pitch_align;
+	int ret;
+
+	/*
+	 * Adreno needs pitch aligned to 32 pixels. Compute the number
+	 * of bytes for a block of 32 pixels at the given color format.
+	 * Use the result as pitch alignment.
+	 */
+	fourcc = drm_driver_color_mode_format(dev, args->bpp);
+	if (fourcc == DRM_FORMAT_INVALID)
+		return -EINVAL;
+	info = drm_format_info(fourcc);
+	if (!info)
+		return -EINVAL;
+	pitch_align = drm_format_info_min_pitch(info, 0, SZ_32);
+	if (!pitch_align || pitch_align > U32_MAX)
+		return -EINVAL;
+	ret = drm_mode_size_dumb(dev, args, pitch_align, 0);
+	if (ret)
+		return ret;
+
 	return msm_gem_new_handle(dev, file, args->size,
 			MSM_BO_SCANOUT | MSM_BO_WC, &args->handle, "dumb");
 }
-- 
2.48.1

[PATCH v4 14/25] drm/nouveau: Compute dumb-buffer sizes with drm_mode_size_dumb()

[Thomas Zimmermann]

Call drm_mode_size_dumb() to compute dumb-buffer scanline pitch and
buffer size. Align the pitch to a multiple of 256.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Cc: Karol Herbst <kherbst@redhat.com>
Cc: Lyude Paul <lyude@redhat.com>
Cc: Danilo Krummrich <dakr@kernel.org>
---
 drivers/gpu/drm/nouveau/nouveau_display.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_display.c b/drivers/gpu/drm/nouveau/nouveau_display.c
index add006fc8d81..daa2528f9c9a 100644
--- a/drivers/gpu/drm/nouveau/nouveau_display.c
+++ b/drivers/gpu/drm/nouveau/nouveau_display.c
@@ -30,6 +30,7 @@
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_client_event.h>
 #include <drm/drm_crtc_helper.h>
+#include <drm/drm_dumb_buffers.h>
 #include <drm/drm_fourcc.h>
 #include <drm/drm_gem_framebuffer_helper.h>
 #include <drm/drm_probe_helper.h>
@@ -808,9 +809,9 @@ nouveau_display_dumb_create(struct drm_file *file_priv, struct drm_device *dev,
 	uint32_t domain;
 	int ret;
 
-	args->pitch = roundup(args->width * (args->bpp / 8), 256);
-	args->size = args->pitch * args->height;
-	args->size = roundup(args->size, PAGE_SIZE);
+	ret = drm_mode_size_dumb(dev, args, SZ_256, 0);
+	if (ret)
+		return ret;
 
 	/* Use VRAM if there is any ; otherwise fallback to system memory */
 	if (nouveau_drm(dev)->client.device.info.ram_size != 0)
-- 
2.48.1

[PATCH v4 15/25] drm/omapdrm: Compute dumb-buffer sizes with drm_mode_size_dumb()

[Thomas Zimmermann]

Call drm_mode_size_dumb() to compute dumb-buffer scanline pitch and
buffer size. Align the pitch to a multiple of 8.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
---
 drivers/gpu/drm/omapdrm/omap_gem.c | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/omapdrm/omap_gem.c b/drivers/gpu/drm/omapdrm/omap_gem.c
index b9c67e4ca360..b8413a2dcdeb 100644
--- a/drivers/gpu/drm/omapdrm/omap_gem.c
+++ b/drivers/gpu/drm/omapdrm/omap_gem.c
@@ -11,6 +11,7 @@
 #include <linux/pfn_t.h>
 #include <linux/vmalloc.h>
 
+#include <drm/drm_dumb_buffers.h>
 #include <drm/drm_prime.h>
 #include <drm/drm_vma_manager.h>
 
@@ -583,15 +584,13 @@ static int omap_gem_object_mmap(struct drm_gem_object *obj, struct vm_area_struc
 int omap_gem_dumb_create(struct drm_file *file, struct drm_device *dev,
 		struct drm_mode_create_dumb *args)
 {
-	union omap_gem_size gsize;
-
-	args->pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
-
-	args->size = PAGE_ALIGN(args->pitch * args->height);
+	union omap_gem_size gsize = { };
+	int ret;
 
-	gsize = (union omap_gem_size){
-		.bytes = args->size,
-	};
+	ret = drm_mode_size_dumb(dev, args, SZ_8, 0);
+	if (ret)
+		return ret;
+	gsize.bytes = args->size;
 
 	return omap_gem_new_handle(dev, file, gsize,
 			OMAP_BO_SCANOUT | OMAP_BO_WC, &args->handle);
-- 
2.48.1

[PATCH v4 16/25] drm/qxl: Compute dumb-buffer sizes with drm_mode_size_dumb()

[Thomas Zimmermann]

Call drm_mode_size_dumb() to compute dumb-buffer scanline pitch
and buffer size. No alignment required.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
---
 drivers/gpu/drm/qxl/qxl_dumb.c | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/qxl/qxl_dumb.c b/drivers/gpu/drm/qxl/qxl_dumb.c
index 17df5c7ccf69..1200946767ce 100644
--- a/drivers/gpu/drm/qxl/qxl_dumb.c
+++ b/drivers/gpu/drm/qxl/qxl_dumb.c
@@ -23,6 +23,8 @@
  *          Alon Levy
  */
 
+#include <drm/drm_dumb_buffers.h>
+
 #include "qxl_drv.h"
 #include "qxl_object.h"
 
@@ -35,14 +37,13 @@ int qxl_mode_dumb_create(struct drm_file *file_priv,
 	struct qxl_device *qdev = to_qxl(dev);
 	struct qxl_bo *qobj;
 	struct drm_gem_object *gobj;
-	uint32_t handle;
 	int r;
 	struct qxl_surface surf;
-	uint32_t pitch, format;
+	u32 format;
 
-	pitch = args->width * ((args->bpp + 1) / 8);
-	args->size = pitch * args->height;
-	args->size = ALIGN(args->size, PAGE_SIZE);
+	r = drm_mode_size_dumb(dev, args, 0, 0);
+	if (r)
+		return r;
 
 	switch (args->bpp) {
 	case 16:
@@ -57,20 +58,18 @@ int qxl_mode_dumb_create(struct drm_file *file_priv,
 
 	surf.width = args->width;
 	surf.height = args->height;
-	surf.stride = pitch;
+	surf.stride = args->pitch;
 	surf.format = format;
 	surf.data = 0;
 
 	r = qxl_gem_object_create_with_handle(qdev, file_priv,
 					      QXL_GEM_DOMAIN_CPU,
 					      args->size, &surf, &gobj,
-					      &handle);
+					      &args->handle);
 	if (r)
 		return r;
 	qobj = gem_to_qxl_bo(gobj);
 	qobj->is_dumb = true;
 	drm_gem_object_put(gobj);
-	args->pitch = pitch;
-	args->handle = handle;
 	return 0;
 }
-- 
2.48.1

[PATCH v4 17/25] drm/renesas/rcar-du: Compute dumb-buffer sizes with drm_mode_size_dumb()

[Thomas Zimmermann]

Call drm_mode_size_dumb() to compute dumb-buffer scanline pitch and
buffer size. Align the pitch according to hardware requirements.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
---
 drivers/gpu/drm/renesas/rcar-du/rcar_du_kms.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/renesas/rcar-du/rcar_du_kms.c b/drivers/gpu/drm/renesas/rcar-du/rcar_du_kms.c
index 70d8ad065bfa..32c8307da522 100644
--- a/drivers/gpu/drm/renesas/rcar-du/rcar_du_kms.c
+++ b/drivers/gpu/drm/renesas/rcar-du/rcar_du_kms.c
@@ -11,6 +11,7 @@
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_crtc.h>
 #include <drm/drm_device.h>
+#include <drm/drm_dumb_buffers.h>
 #include <drm/drm_framebuffer.h>
 #include <drm/drm_gem_dma_helper.h>
 #include <drm/drm_gem_framebuffer_helper.h>
@@ -407,8 +408,8 @@ int rcar_du_dumb_create(struct drm_file *file, struct drm_device *dev,
 			struct drm_mode_create_dumb *args)
 {
 	struct rcar_du_device *rcdu = to_rcar_du_device(dev);
-	unsigned int min_pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
 	unsigned int align;
+	int ret;
 
 	/*
 	 * The R8A7779 DU requires a 16 pixels pitch alignment as documented,
@@ -419,7 +420,9 @@ int rcar_du_dumb_create(struct drm_file *file, struct drm_device *dev,
 	else
 		align = 16 * args->bpp / 8;
 
-	args->pitch = roundup(min_pitch, align);
+	ret = drm_mode_size_dumb(dev, args, align, 0);
+	if (ret)
+		return ret;
 
 	return drm_gem_dma_dumb_create_internal(file, dev, args);
 }
-- 
2.48.1

[PATCH v4 18/25] drm/renesas/rz-du: Compute dumb-buffer sizes with drm_mode_size_dumb()

[Thomas Zimmermann]

Call drm_mode_size_dumb() to compute dumb-buffer scanline pitch and
buffer size. Align the pitch according to hardware requirements.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Biju Das <biju.das.jz@bp.renesas.com>
---
 drivers/gpu/drm/renesas/rz-du/rzg2l_du_kms.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/renesas/rz-du/rzg2l_du_kms.c b/drivers/gpu/drm/renesas/rz-du/rzg2l_du_kms.c
index 90c6269ccd29..f752369cd52f 100644
--- a/drivers/gpu/drm/renesas/rz-du/rzg2l_du_kms.c
+++ b/drivers/gpu/drm/renesas/rz-du/rzg2l_du_kms.c
@@ -75,10 +75,11 @@ const struct rzg2l_du_format_info *rzg2l_du_format_info(u32 fourcc)
 int rzg2l_du_dumb_create(struct drm_file *file, struct drm_device *dev,
 			 struct drm_mode_create_dumb *args)
 {
-	unsigned int min_pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
-	unsigned int align = 16 * args->bpp / 8;
+	int ret;
 
-	args->pitch = roundup(min_pitch, align);
+	ret = drm_mode_size_dumb(dev, args, 16 * args->bpp / 8, 0);
+	if (ret)
+		return ret;
 
 	return drm_gem_dma_dumb_create_internal(file, dev, args);
 }
-- 
2.48.1

Re: [PATCH v4 18/25] drm/renesas/rz-du: Compute dumb-buffer sizes with drm_mode_size_dumb()

[kernel test robot]

Hi Thomas,

kernel test robot noticed the following build errors:

[auto build test ERROR on next-20250311]
[also build test ERROR on v6.14-rc6]
[cannot apply to drm-exynos/exynos-drm-next rockchip/for-next tegra/for-next drm-xe/drm-xe-next linus/master v6.14-rc6 v6.14-rc5 v6.14-rc4]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Thomas-Zimmermann/drm-dumb-buffers-Sanitize-output-on-errors/20250311-235818
base:   next-20250311
patch link:    https://lore.kernel.org/r/20250311155120.442633-19-tzimmermann%40suse.de
patch subject: [PATCH v4 18/25] drm/renesas/rz-du: Compute dumb-buffer sizes with drm_mode_size_dumb()
config: powerpc64-randconfig-003-20250313 (https://download.01.org/0day-ci/archive/20250313/202503130956.VyNIuYfU-lkp@intel.com/config)
compiler: powerpc64-linux-gcc (GCC) 14.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250313/202503130956.VyNIuYfU-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202503130956.VyNIuYfU-lkp@intel.com/

All errors (new ones prefixed by >>):

   drivers/gpu/drm/renesas/rz-du/rzg2l_du_kms.c: In function 'rzg2l_du_dumb_create':
>> drivers/gpu/drm/renesas/rz-du/rzg2l_du_kms.c:80:15: error: implicit declaration of function 'drm_mode_size_dumb'; did you mean 'drm_mode_set_name'? [-Wimplicit-function-declaration]
      80 |         ret = drm_mode_size_dumb(dev, args, 16 * args->bpp / 8, 0);
         |               ^~~~~~~~~~~~~~~~~~
         |               drm_mode_set_name


vim +80 drivers/gpu/drm/renesas/rz-du/rzg2l_du_kms.c

    70	
    71	/* -----------------------------------------------------------------------------
    72	 * Frame buffer
    73	 */
    74	
    75	int rzg2l_du_dumb_create(struct drm_file *file, struct drm_device *dev,
    76				 struct drm_mode_create_dumb *args)
    77	{
    78		int ret;
    79	
  > 80		ret = drm_mode_size_dumb(dev, args, 16 * args->bpp / 8, 0);
    81		if (ret)
    82			return ret;
    83	
    84		return drm_gem_dma_dumb_create_internal(file, dev, args);
    85	}
    86	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Re: [PATCH v4 18/25] drm/renesas/rz-du: Compute dumb-buffer sizes with drm_mode_size_dumb()

[kernel test robot]

Hi Thomas,

kernel test robot noticed the following build errors:

[auto build test ERROR on next-20250311]
[also build test ERROR on v6.14-rc6]
[cannot apply to drm-exynos/exynos-drm-next rockchip/for-next tegra/for-next drm-xe/drm-xe-next linus/master v6.14-rc6 v6.14-rc5 v6.14-rc4]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Thomas-Zimmermann/drm-dumb-buffers-Sanitize-output-on-errors/20250311-235818
base:   next-20250311
patch link:    https://lore.kernel.org/r/20250311155120.442633-19-tzimmermann%40suse.de
patch subject: [PATCH v4 18/25] drm/renesas/rz-du: Compute dumb-buffer sizes with drm_mode_size_dumb()
config: i386-buildonly-randconfig-003-20250313 (https://download.01.org/0day-ci/archive/20250313/202503131309.ZzS9Tova-lkp@intel.com/config)
compiler: clang version 19.1.7 (https://github.com/llvm/llvm-project cd708029e0b2869e80abe31ddb175f7c35361f90)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250313/202503131309.ZzS9Tova-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202503131309.ZzS9Tova-lkp@intel.com/

All errors (new ones prefixed by >>):

   In file included from drivers/gpu/drm/renesas/rz-du/rzg2l_du_kms.c:10:
   In file included from include/drm/drm_atomic.h:31:
   In file included from include/drm/drm_crtc.h:32:
   In file included from include/drm/drm_modes.h:33:
   In file included from include/drm/drm_connector.h:32:
   In file included from include/drm/drm_util.h:36:
   In file included from include/linux/kgdb.h:19:
   In file included from include/linux/kprobes.h:28:
   In file included from include/linux/ftrace.h:13:
   In file included from include/linux/kallsyms.h:13:
   In file included from include/linux/mm.h:2296:
   include/linux/vmstat.h:507:36: warning: arithmetic between different enumeration types ('enum node_stat_item' and 'enum lru_list') [-Wenum-enum-conversion]
     507 |         return node_stat_name(NR_LRU_BASE + lru) + 3; // skip "nr_"
         |                               ~~~~~~~~~~~ ^ ~~~
>> drivers/gpu/drm/renesas/rz-du/rzg2l_du_kms.c:80:8: error: call to undeclared function 'drm_mode_size_dumb'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
      80 |         ret = drm_mode_size_dumb(dev, args, 16 * args->bpp / 8, 0);
         |               ^
   drivers/gpu/drm/renesas/rz-du/rzg2l_du_kms.c:80:8: note: did you mean 'drm_mode_set_name'?
   include/drm/drm_modes.h:530:6: note: 'drm_mode_set_name' declared here
     530 | void drm_mode_set_name(struct drm_display_mode *mode);
         |      ^
   1 warning and 1 error generated.


vim +/drm_mode_size_dumb +80 drivers/gpu/drm/renesas/rz-du/rzg2l_du_kms.c

    70	
    71	/* -----------------------------------------------------------------------------
    72	 * Frame buffer
    73	 */
    74	
    75	int rzg2l_du_dumb_create(struct drm_file *file, struct drm_device *dev,
    76				 struct drm_mode_create_dumb *args)
    77	{
    78		int ret;
    79	
  > 80		ret = drm_mode_size_dumb(dev, args, 16 * args->bpp / 8, 0);
    81		if (ret)
    82			return ret;
    83	
    84		return drm_gem_dma_dumb_create_internal(file, dev, args);
    85	}
    86	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

[PATCH v4 19/25] drm/rockchip: Compute dumb-buffer sizes with drm_mode_size_dumb()

[Thomas Zimmermann]

Call drm_mode_size_dumb() to compute dumb-buffer scanline pitch and
buffer size. Align the pitch to a multiple of 64.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Heiko Stuebner <heiko@sntech.de>
Cc: Sandy Huang <hjc@rock-chips.com>
Cc: "Heiko Stübner" <heiko@sntech.de>
Cc: Andy Yan <andy.yan@rock-chips.com>
---
 drivers/gpu/drm/rockchip/rockchip_drm_gem.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_gem.c b/drivers/gpu/drm/rockchip/rockchip_drm_gem.c
index 6330b883efc3..3bd06202e232 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_gem.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_gem.c
@@ -9,6 +9,7 @@
 #include <linux/vmalloc.h>
 
 #include <drm/drm.h>
+#include <drm/drm_dumb_buffers.h>
 #include <drm/drm_fb_helper.h>
 #include <drm/drm_gem.h>
 #include <drm/drm_gem_dma_helper.h>
@@ -403,13 +404,12 @@ int rockchip_gem_dumb_create(struct drm_file *file_priv,
 			     struct drm_mode_create_dumb *args)
 {
 	struct rockchip_gem_object *rk_obj;
-	int min_pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
+	int ret;
 
-	/*
-	 * align to 64 bytes since Mali requires it.
-	 */
-	args->pitch = ALIGN(min_pitch, 64);
-	args->size = args->pitch * args->height;
+	/* 64-byte alignment required by Mali */
+	ret = drm_mode_size_dumb(dev, args, SZ_64, 0);
+	if (ret)
+		return ret;
 
 	rk_obj = rockchip_gem_create_with_handle(file_priv, dev, args->size,
 						 &args->handle);
-- 
2.48.1

[PATCH v4 20/25] drm/tegra: Compute dumb-buffer sizes with drm_mode_size_dumb()

[Thomas Zimmermann]

Call drm_mode_size_dumb() to compute dumb-buffer scanline pitch and
buffer size. Align the pitch according to hardware requirements.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Thierry Reding <treding@nvidia.com>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Mikko Perttunen <mperttunen@nvidia.com>
---
 drivers/gpu/drm/tegra/gem.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/tegra/gem.c b/drivers/gpu/drm/tegra/gem.c
index ace3e5a805cf..4d88e71192fb 100644
--- a/drivers/gpu/drm/tegra/gem.c
+++ b/drivers/gpu/drm/tegra/gem.c
@@ -16,6 +16,7 @@
 #include <linux/vmalloc.h>
 
 #include <drm/drm_drv.h>
+#include <drm/drm_dumb_buffers.h>
 #include <drm/drm_prime.h>
 #include <drm/tegra_drm.h>
 
@@ -543,12 +544,13 @@ void tegra_bo_free_object(struct drm_gem_object *gem)
 int tegra_bo_dumb_create(struct drm_file *file, struct drm_device *drm,
 			 struct drm_mode_create_dumb *args)
 {
-	unsigned int min_pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
 	struct tegra_drm *tegra = drm->dev_private;
 	struct tegra_bo *bo;
+	int ret;
 
-	args->pitch = round_up(min_pitch, tegra->pitch_align);
-	args->size = args->pitch * args->height;
+	ret = drm_mode_size_dumb(drm, args, tegra->pitch_align, 0);
+	if (ret)
+		return ret;
 
 	bo = tegra_bo_create_with_handle(file, drm, args->size, 0,
 					 &args->handle);
-- 
2.48.1

[PATCH v4 21/25] drm/virtio: Compute dumb-buffer sizes with drm_mode_size_dumb()

[Thomas Zimmermann]

Call drm_mode_size_dumb() to compute dumb-buffer scanline pitch and
buffer size. Align the pitch to a multiple of 4.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Cc: David Airlie <airlied@redhat.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Gurchetan Singh <gurchetansingh@chromium.org>
Cc: Chia-I Wu <olvaffe@gmail.com>
---
 drivers/gpu/drm/virtio/virtgpu_gem.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/virtio/virtgpu_gem.c b/drivers/gpu/drm/virtio/virtgpu_gem.c
index dde8fc1a3689..5e5e38d53990 100644
--- a/drivers/gpu/drm/virtio/virtgpu_gem.c
+++ b/drivers/gpu/drm/virtio/virtgpu_gem.c
@@ -23,6 +23,7 @@
  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  */
 
+#include <drm/drm_dumb_buffers.h>
 #include <drm/drm_file.h>
 #include <drm/drm_fourcc.h>
 
@@ -66,15 +67,14 @@ int virtio_gpu_mode_dumb_create(struct drm_file *file_priv,
 	struct virtio_gpu_object_params params = { 0 };
 	struct virtio_gpu_device *vgdev = dev->dev_private;
 	int ret;
-	uint32_t pitch;
+
+	ret = drm_mode_size_dumb(dev, args, SZ_4, 0);
+	if (ret)
+		return ret;
 
 	if (args->bpp != 32)
 		return -EINVAL;
 
-	pitch = args->width * 4;
-	args->size = pitch * args->height;
-	args->size = ALIGN(args->size, PAGE_SIZE);
-
 	params.format = virtio_gpu_translate_format(DRM_FORMAT_HOST_XRGB8888);
 	params.width = args->width;
 	params.height = args->height;
@@ -92,7 +92,6 @@ int virtio_gpu_mode_dumb_create(struct drm_file *file_priv,
 	if (ret)
 		goto fail;
 
-	args->pitch = pitch;
 	return ret;
 
 fail:
-- 
2.48.1

[PATCH v4 22/25] drm/vmwgfx: Compute dumb-buffer sizes with drm_mode_size_dumb()

[Thomas Zimmermann]

Call drm_mode_size_dumb() to compute dumb-buffer scanline pitch
and buffer size. No alignment required.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Zack Rusin <zack.rusin@broadcom.com>
Cc: Zack Rusin <zack.rusin@broadcom.com>
Cc: Broadcom internal kernel review list <bcm-kernel-feedback-list@broadcom.com>
---
 drivers/gpu/drm/vmwgfx/vmwgfx_surface.c | 21 ++++-----------------
 1 file changed, 4 insertions(+), 17 deletions(-)

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
index 02ab65cc63ec..c3a4ea713559 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
@@ -15,6 +15,7 @@
 #include "vmw_surface_cache.h"
 #include "device_include/svga3d_surfacedefs.h"
 
+#include <drm/drm_dumb_buffers.h>
 #include <drm/ttm/ttm_placement.h>
 
 #define SVGA3D_FLAGS_64(upper32, lower32) (((uint64_t)upper32 << 32) | lower32)
@@ -2270,23 +2271,9 @@ int vmw_dumb_create(struct drm_file *file_priv,
 	 * contents is going to be rendered guest side.
 	 */
 	if (!dev_priv->has_mob || !vmw_supports_3d(dev_priv)) {
-		int cpp = DIV_ROUND_UP(args->bpp, 8);
-
-		switch (cpp) {
-		case 1: /* DRM_FORMAT_C8 */
-		case 2: /* DRM_FORMAT_RGB565 */
-		case 4: /* DRM_FORMAT_XRGB8888 */
-			break;
-		default:
-			/*
-			 * Dumb buffers don't allow anything else.
-			 * This is tested via IGT's dumb_buffers
-			 */
-			return -EINVAL;
-		}
-
-		args->pitch = args->width * cpp;
-		args->size = ALIGN(args->pitch * args->height, PAGE_SIZE);
+		ret = drm_mode_size_dumb(dev, args, 0, 0);
+		if (ret)
+			return ret;
 
 		ret = vmw_gem_object_create_with_handle(dev_priv, file_priv,
 							args->size, &args->handle,
-- 
2.48.1

[PATCH v4 23/25] drm/xe: Compute dumb-buffer sizes with drm_mode_size_dumb()

[Thomas Zimmermann]

Call drm_mode_size_dumb() to compute dumb-buffer scanline pitch
and buffer size. Align the pitch to a multiple of 8. Align the
buffer size according to hardware requirements.

Xe's internal calculation allowed for 64-bit wide buffer sizes, but
the ioctl's internal checks always verified against 32-bit wide limits.
Hance, it is safe to limit the driver code to 32-bit calculations as
well.

v3:
- mention 32-bit calculation in commit description (Matthew)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Cc: "Thomas Hellström" <thomas.hellstrom@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
---
 drivers/gpu/drm/xe/xe_bo.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_bo.c b/drivers/gpu/drm/xe/xe_bo.c
index 64f9c936eea0..471aab61176e 100644
--- a/drivers/gpu/drm/xe/xe_bo.c
+++ b/drivers/gpu/drm/xe/xe_bo.c
@@ -9,6 +9,7 @@
 #include <linux/nospec.h>
 
 #include <drm/drm_drv.h>
+#include <drm/drm_dumb_buffers.h>
 #include <drm/drm_gem_ttm_helper.h>
 #include <drm/drm_managed.h>
 #include <drm/ttm/ttm_backup.h>
@@ -2910,14 +2911,13 @@ int xe_bo_dumb_create(struct drm_file *file_priv,
 	struct xe_device *xe = to_xe_device(dev);
 	struct xe_bo *bo;
 	uint32_t handle;
-	int cpp = DIV_ROUND_UP(args->bpp, 8);
 	int err;
 	u32 page_size = max_t(u32, PAGE_SIZE,
 		xe->info.vram_flags & XE_VRAM_FLAGS_NEED64K ? SZ_64K : SZ_4K);
 
-	args->pitch = ALIGN(args->width * cpp, 64);
-	args->size = ALIGN(mul_u32_u32(args->pitch, args->height),
-			   page_size);
+	err = drm_mode_size_dumb(dev, args, SZ_64, page_size);
+	if (err)
+		return err;
 
 	bo = xe_bo_create_user(xe, NULL, NULL, args->size,
 			       DRM_XE_GEM_CPU_CACHING_WC,
-- 
2.48.1

[PATCH v4 24/25] drm/xen: Compute dumb-buffer sizes with drm_mode_size_dumb()

[Thomas Zimmermann]

Call drm_mode_size_dumb() to compute dumb-buffer scanline pitch
and buffer size. Align the pitch to a multiple of 8.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
---
 drivers/gpu/drm/xen/xen_drm_front.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/xen/xen_drm_front.c b/drivers/gpu/drm/xen/xen_drm_front.c
index 1bda7ef606cc..fd2f250fbc33 100644
--- a/drivers/gpu/drm/xen/xen_drm_front.c
+++ b/drivers/gpu/drm/xen/xen_drm_front.c
@@ -14,6 +14,7 @@
 
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_drv.h>
+#include <drm/drm_dumb_buffers.h>
 #include <drm/drm_ioctl.h>
 #include <drm/drm_probe_helper.h>
 #include <drm/drm_file.h>
@@ -414,8 +415,10 @@ static int xen_drm_drv_dumb_create(struct drm_file *filp,
 	 * object without pages etc.
 	 * For details also see drm_gem_handle_create
 	 */
-	args->pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
-	args->size = args->pitch * args->height;
+
+	ret = drm_mode_size_dumb(dev, args, SZ_8, 0);
+	if (ret)
+		return ret;
 
 	obj = xen_drm_front_gem_create(dev, args->size);
 	if (IS_ERR(obj)) {
-- 
2.48.1

[PATCH v4 25/25] drm/xlnx: Compute dumb-buffer sizes with drm_mode_size_dumb()

[Thomas Zimmermann]

Call drm_mode_size_dumb() to compute dumb-buffer scanline pitch and
buffer size. Align the pitch according to hardware requirements.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
---
 drivers/gpu/drm/xlnx/zynqmp_kms.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/xlnx/zynqmp_kms.c b/drivers/gpu/drm/xlnx/zynqmp_kms.c
index b47463473472..7ea0cd4f71d3 100644
--- a/drivers/gpu/drm/xlnx/zynqmp_kms.c
+++ b/drivers/gpu/drm/xlnx/zynqmp_kms.c
@@ -19,6 +19,7 @@
 #include <drm/drm_crtc.h>
 #include <drm/drm_device.h>
 #include <drm/drm_drv.h>
+#include <drm/drm_dumb_buffers.h>
 #include <drm/drm_encoder.h>
 #include <drm/drm_fbdev_dma.h>
 #include <drm/drm_fourcc.h>
@@ -363,10 +364,12 @@ static int zynqmp_dpsub_dumb_create(struct drm_file *file_priv,
 				    struct drm_mode_create_dumb *args)
 {
 	struct zynqmp_dpsub *dpsub = to_zynqmp_dpsub(drm);
-	unsigned int pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
+	int ret;
 
 	/* Enforce the alignment constraints of the DMA engine. */
-	args->pitch = ALIGN(pitch, dpsub->dma_align);
+	ret = drm_mode_size_dumb(drm, args, dpsub->dma_align, 0);
+	if (ret)
+		return ret;
 
 	return drm_gem_dma_dumb_create_internal(file_priv, drm, args);
 }
-- 
2.48.1

Re: [PATCH v4 00/25] drm/dumb-buffers: Fix and improve buffer-size calculation

[Thomas Zimmermann]

ping

I'm still looking for more reviews; especially patches 1 and 2.

Best regards
Thomas

Am 11.03.25 um 16:47 schrieb Thomas Zimmermann:
> Dumb-buffer pitch and size is specified by width, height, bits-per-pixel
> plus various hardware-specific alignments. The calculation of these
> values is inconsistent and duplicated among drivers. The results for
> formats with bpp < 8 are sometimes incorrect.
>
> This series fixes this for most drivers. Default scanline pitch and
> buffer size are now calculated with the existing 4CC helpers. There is
> a new helper drm_mode_size_dumb() that calculates scanline pitch and
> buffer size according to driver requirements.
>
> The series fixes the common GEM implementations for DMA, SHMEM and
> VRAM. It further changes most implementations of dumb_create to use
> the new helper. A small number of drivers has more complicated
> calculations and will be updated by a later patches.
>
> v4:
> - improve UAPI documentation
> - document bpp special cases
> - use drm_warn_once()
> - add TODO lists
> - armada: fix pitch alignment
> v3:
> - document UAPI semantics
> - fall back to bpp-based allocation for unknown color modes
> - cleanups
> v2:
> - rewrite series
> - convert many individual drivers besides the shared GEM helpers
>
> Thomas Zimmermann (25):
>    drm/dumb-buffers: Sanitize output on errors
>    drm/dumb-buffers: Provide helper to set pitch and size
>    drm/gem-dma: Compute dumb-buffer sizes with drm_mode_size_dumb()
>    drm/gem-shmem: Compute dumb-buffer sizes with drm_mode_size_dumb()
>    drm/gem-vram: Compute dumb-buffer sizes with drm_mode_size_dumb()
>    drm/armada: Compute dumb-buffer sizes with drm_mode_size_dumb()
>    drm/exynos: Compute dumb-buffer sizes with drm_mode_size_dumb()
>    drm/gma500: Compute dumb-buffer sizes with drm_mode_size_dumb()
>    drm/hibmc: Compute dumb-buffer sizes with drm_mode_size_dumb()
>    drm/imx/ipuv3: Compute dumb-buffer sizes with drm_mode_size_dumb()
>    drm/loongson: Compute dumb-buffer sizes with drm_mode_size_dumb()
>    drm/mediatek: Compute dumb-buffer sizes with drm_mode_size_dumb()
>    drm/msm: Compute dumb-buffer sizes with drm_mode_size_dumb()
>    drm/nouveau: Compute dumb-buffer sizes with drm_mode_size_dumb()
>    drm/omapdrm: Compute dumb-buffer sizes with drm_mode_size_dumb()
>    drm/qxl: Compute dumb-buffer sizes with drm_mode_size_dumb()
>    drm/renesas/rcar-du: Compute dumb-buffer sizes with
>      drm_mode_size_dumb()
>    drm/renesas/rz-du: Compute dumb-buffer sizes with drm_mode_size_dumb()
>    drm/rockchip: Compute dumb-buffer sizes with drm_mode_size_dumb()
>    drm/tegra: Compute dumb-buffer sizes with drm_mode_size_dumb()
>    drm/virtio: Compute dumb-buffer sizes with drm_mode_size_dumb()
>    drm/vmwgfx: Compute dumb-buffer sizes with drm_mode_size_dumb()
>    drm/xe: Compute dumb-buffer sizes with drm_mode_size_dumb()
>    drm/xen: Compute dumb-buffer sizes with drm_mode_size_dumb()
>    drm/xlnx: Compute dumb-buffer sizes with drm_mode_size_dumb()
>
>   Documentation/gpu/todo.rst                    |  28 +++
>   drivers/gpu/drm/armada/armada_gem.c           |  16 +-
>   drivers/gpu/drm/drm_dumb_buffers.c            | 172 ++++++++++++++++--
>   drivers/gpu/drm/drm_gem_dma_helper.c          |   7 +-
>   drivers/gpu/drm/drm_gem_shmem_helper.c        |  16 +-
>   drivers/gpu/drm/drm_gem_vram_helper.c         |  89 +++------
>   drivers/gpu/drm/exynos/exynos_drm_gem.c       |   8 +-
>   drivers/gpu/drm/gma500/gem.c                  |  21 +--
>   .../gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c   |  25 ++-
>   drivers/gpu/drm/imx/ipuv3/imx-drm-core.c      |  29 ++-
>   drivers/gpu/drm/loongson/lsdc_gem.c           |  29 +--
>   drivers/gpu/drm/mediatek/mtk_gem.c            |  13 +-
>   drivers/gpu/drm/msm/msm_gem.c                 |  27 ++-
>   drivers/gpu/drm/nouveau/nouveau_display.c     |   7 +-
>   drivers/gpu/drm/omapdrm/omap_gem.c            |  15 +-
>   drivers/gpu/drm/qxl/qxl_dumb.c                |  17 +-
>   drivers/gpu/drm/renesas/rcar-du/rcar_du_kms.c |   7 +-
>   drivers/gpu/drm/renesas/rz-du/rzg2l_du_kms.c  |   7 +-
>   drivers/gpu/drm/rockchip/rockchip_drm_gem.c   |  12 +-
>   drivers/gpu/drm/tegra/gem.c                   |   8 +-
>   drivers/gpu/drm/virtio/virtgpu_gem.c          |  11 +-
>   drivers/gpu/drm/vmwgfx/vmwgfx_surface.c       |  21 +--
>   drivers/gpu/drm/xe/xe_bo.c                    |   8 +-
>   drivers/gpu/drm/xen/xen_drm_front.c           |   7 +-
>   drivers/gpu/drm/xlnx/zynqmp_kms.c             |   7 +-
>   include/drm/drm_dumb_buffers.h                |  14 ++
>   include/drm/drm_gem_vram_helper.h             |   6 -
>   include/uapi/drm/drm_mode.h                   |  50 ++++-
>   28 files changed, 449 insertions(+), 228 deletions(-)
>   create mode 100644 include/drm/drm_dumb_buffers.h
>

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)