[PATCH v6 00/25] drm/dumb-buffers: Fix and improve buffer-size calculation

[PATCH v6 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.

v6:
- extend TODO item (Tomi)
- fix typos in documentation (Tomi)
v5:
- use check_mul_overflow() for overflow test (Tomi)
- imx: fix intermediate code (Tomi)
- rz-du: include dumb-buffers header
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                    |  37 ++++
 drivers/gpu/drm/armada/armada_gem.c           |  16 +-
 drivers/gpu/drm/drm_dumb_buffers.c            | 170 ++++++++++++++++--
 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  |   8 +-
 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, 457 insertions(+), 228 deletions(-)
 create mode 100644 include/drm/drm_dumb_buffers.h

-- 
2.50.1

[PATCH v6 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>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
---
 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,
-- 
2.50.1

[PATCH v6 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.

v6:
- document additional use cases for DUMB_CREATE2 in TODO list (Tomi)
- fix typos in documentation (Tomi)
v5:
- check for overflows with check_mul_overflow() (Tomi)
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>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
---
 Documentation/gpu/todo.rst         |  37 ++++++++
 drivers/gpu/drm/drm_dumb_buffers.c | 130 +++++++++++++++++++++++++++++
 include/drm/drm_dumb_buffers.h     |  14 ++++
 include/uapi/drm/drm_mode.h        |  50 ++++++++++-
 4 files changed, 230 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 92db80793bba..98ed38241dc6 100644
--- a/Documentation/gpu/todo.rst
+++ b/Documentation/gpu/todo.rst
@@ -648,6 +648,43 @@ Contact: Thomas Zimmermann <tzimmermann@suse.de>, Simona Vetter
 
 Level: Advanced
 
+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 an idea of the supported pixel
+format. But userspace effectively has to guess the correct values. It really
+only works reliably 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.
+
+It might also be helpful to userspace to query information about the size of
+a potential buffer, if allocated. Userspace would supply geometry and format;
+the kernel would return minimal allocation sizes and scanline pitch. There is
+interest to allocate that memory from another device and provide it to the
+DRM driver (say via dma-buf).
+
+Another requested feature is the ability to allocate a buffer by size, without
+format. Accelators use this for their buffer allocation and it could likely be
+generalized.
+
+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
 
 Better Testing
 ==============
diff --git a/drivers/gpu/drm/drm_dumb_buffers.c b/drivers/gpu/drm/drm_dumb_buffers.c
index 9916aaf5b3f2..e9eed9a5b760 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 +59,134 @@
  * 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);
+
+	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 */
+
+	if (check_mul_overflow(args->height, pitch, &size))
+		return -EINVAL;
+	size = ALIGN(size, 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 a122bea25593..1e0e02a79b5c 100644
--- a/include/uapi/drm/drm_mode.h
+++ b/include/uapi/drm/drm_mode.h
@@ -1066,7 +1066,7 @@ 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
@@ -1074,6 +1074,54 @@ 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;
-- 
2.50.1

[PATCH v6 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.

v5:
- avoid reset of arguments (Tomi)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
---
 drivers/gpu/drm/drm_gem_dma_helper.c     | 7 +++++--
 drivers/gpu/drm/imx/ipuv3/imx-drm-core.c | 4 +++-
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/drm_gem_dma_helper.c b/drivers/gpu/drm/drm_gem_dma_helper.c
index 4f0320df858f..ab1a70b1d6f1 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..af4a30311e18 100644
--- a/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c
+++ b/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c
@@ -145,8 +145,10 @@ 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);
+	ret = drm_gem_dma_dumb_create_internal(file_priv, drm, args);
 	if (ret)
 		return ret;
 
-- 
2.50.1

Re: [PATCH v6 03/25] drm/gem-dma: Compute dumb-buffer sizes with drm_mode_size_dumb()

[Ludovic.Desroches]

On 8/21/25 10:17, 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.
> 
> v5:
> - avoid reset of arguments (Tomi)
> 
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
> ---
>   drivers/gpu/drm/drm_gem_dma_helper.c     | 7 +++++--
>   drivers/gpu/drm/imx/ipuv3/imx-drm-core.c | 4 +++-
>   2 files changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_gem_dma_helper.c b/drivers/gpu/drm/drm_gem_dma_helper.c
> index 4f0320df858f..ab1a70b1d6f1 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;

Hi,

Was it intentional for this change to alter the pitch?

The alignment requirement has been updated—from 8-bit alignment to 
64-bit alignment. Since the pitch is expressed in bytes, we should pass 
SZ_1 instead of SZ_8 for hw_patch_align.

For example, for an 850×480 framebuffer at 16 bpp, the pitch should be 
1700 bytes. With the new alignment, the pitch becomes 1704 bytes.

Please let me know if you’d like me to submit a fix.

Regards,
Ludovic


>   
>   	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..af4a30311e18 100644
> --- a/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c
> +++ b/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c
> @@ -145,8 +145,10 @@ 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);
> +	ret = drm_gem_dma_dumb_create_internal(file_priv, drm, args);
>   	if (ret)
>   		return ret;
>   

Re: [PATCH v6 03/25] drm/gem-dma: Compute dumb-buffer sizes with drm_mode_size_dumb()

[Thomas Zimmermann]

Hi

Am 25.11.25 um 15:39 schrieb Ludovic.Desroches@microchip.com:
> On 8/21/25 10:17, 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.

I missed a chance to explain it here. :/

>>
>> 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.
>>
>> v5:
>> - avoid reset of arguments (Tomi)
>>
>> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
>> Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
>> ---
>>    drivers/gpu/drm/drm_gem_dma_helper.c     | 7 +++++--
>>    drivers/gpu/drm/imx/ipuv3/imx-drm-core.c | 4 +++-
>>    2 files changed, 8 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_gem_dma_helper.c b/drivers/gpu/drm/drm_gem_dma_helper.c
>> index 4f0320df858f..ab1a70b1d6f1 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;
> Hi,
>
> Was it intentional for this change to alter the pitch?

Most hardware does not need the pitch to be of a certain alignment. But 
these buffers are possibly shared with other hardware, which sometimes 
needs alignment to certain values. Using SZ_8 improves compatible with 
that hardware.

>
> The alignment requirement has been updated—from 8-bit alignment to
> 64-bit alignment. Since the pitch is expressed in bytes, we should pass
> SZ_1 instead of SZ_8 for hw_patch_align.
>
> For example, for an 850×480 framebuffer at 16 bpp, the pitch should be
> 1700 bytes. With the new alignment, the pitch becomes 1704 bytes.

Many display modes have an 8-byte alignment in their width. 850 pixels 
is somewhat of an exception.

>
> Please let me know if you’d like me to submit a fix.

Do you see a bug with your hardware? Unless this creates a real problem, 
I'd like to keep it as it is now.

Best regards
Thomas

>
> Regards,
> Ludovic
>
>
>>    
>>    	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..af4a30311e18 100644
>> --- a/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c
>> +++ b/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c
>> @@ -145,8 +145,10 @@ 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);
>> +	ret = drm_gem_dma_dumb_create_internal(file_priv, drm, args);
>>    	if (ret)
>>    		return ret;
>>    

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
GF: Jochen Jaser, Andrew McDonald, Werner Knoblich, (HRB 36809, AG Nürnberg)

Re: [PATCH v6 03/25] drm/gem-dma: Compute dumb-buffer sizes with drm_mode_size_dumb()

[Ludovic.Desroches]

On 11/25/25 16:03, Thomas Zimmermann wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know 
> the content is safe
> 
> Hi
> 
> Am 25.11.25 um 15:39 schrieb Ludovic.Desroches@microchip.com:
>> On 8/21/25 10:17, 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.
> 
> I missed a chance to explain it here. :/

I was wondering if it was 8-bits or 8-bytes.

> 
>>>
>>> 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.
>>>
>>> v5:
>>> - avoid reset of arguments (Tomi)
>>>
>>> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
>>> Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
>>> ---
>>>    drivers/gpu/drm/drm_gem_dma_helper.c     | 7 +++++--
>>>    drivers/gpu/drm/imx/ipuv3/imx-drm-core.c | 4 +++-
>>>    2 files changed, 8 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/drm_gem_dma_helper.c b/drivers/gpu/drm/ 
>>> drm_gem_dma_helper.c
>>> index 4f0320df858f..ab1a70b1d6f1 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;
>> Hi,
>>
>> Was it intentional for this change to alter the pitch?
> 
> Most hardware does not need the pitch to be of a certain alignment. But
> these buffers are possibly shared with other hardware, which sometimes
> needs alignment to certain values. Using SZ_8 improves compatible with
> that hardware.
> 
>>
>> The alignment requirement has been updated—from 8-bit alignment to
>> 64-bit alignment. Since the pitch is expressed in bytes, we should pass
>> SZ_1 instead of SZ_8 for hw_patch_align.
>>
>> For example, for an 850×480 framebuffer at 16 bpp, the pitch should be
>> 1700 bytes. With the new alignment, the pitch becomes 1704 bytes.
> 
> Many display modes have an 8-byte alignment in their width. 850 pixels
> is somewhat of an exception.

Indeed, but overlay-type planes are often used to display windows that 
are not the same size as the screen, and therefore potentially not on 
8-bytes aligned.

> 
>>
>> Please let me know if you’d like me to submit a fix.
> 
> Do you see a bug with your hardware? Unless this creates a real problem,
> I'd like to keep it as it is now.

Yes, that’s how I noticed this change. I have an application that 
requests a framebuffer larger than my screen, in this case 850x480 in 
RGB565 for an 800x480 display. So I have a pitch of 1700 bytes. Now it’s 
using a pitch of 1704, which shifts my lines.

Regards,
Ludovic

> 
> Best regards
> Thomas
> 
>>
>> Regards,
>> Ludovic
>>
>>
>>>
>>>      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..af4a30311e18 100644
>>> --- a/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c
>>> +++ b/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c
>>> @@ -145,8 +145,10 @@ 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);
>>> +    ret = drm_gem_dma_dumb_create_internal(file_priv, drm, args);
>>>      if (ret)
>>>              return ret;
>>>
> 
> -- 
> -- 
> Thomas Zimmermann
> Graphics Driver Developer
> SUSE Software Solutions Germany GmbH
> Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
> GF: Jochen Jaser, Andrew McDonald, Werner Knoblich, (HRB 36809, AG 
> Nürnberg)
> 
> 

Re: [PATCH v6 03/25] drm/gem-dma: Compute dumb-buffer sizes with drm_mode_size_dumb()

[Thomas Zimmermann]

Hi

Am 26.11.25 um 07:24 schrieb Ludovic.Desroches@microchip.com:
> On 11/25/25 16:03, Thomas Zimmermann wrote:
>> EXTERNAL EMAIL: Do not click links or open attachments unless you know
>> the content is safe
>>
>> Hi
>>
>> Am 25.11.25 um 15:39 schrieb Ludovic.Desroches@microchip.com:
>>> On 8/21/25 10:17, 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.
>> I missed a chance to explain it here. :/
> I was wondering if it was 8-bits or 8-bytes.
>
>>>> 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.
>>>>
>>>> v5:
>>>> - avoid reset of arguments (Tomi)
>>>>
>>>> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
>>>> Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
>>>> ---
>>>>     drivers/gpu/drm/drm_gem_dma_helper.c     | 7 +++++--
>>>>     drivers/gpu/drm/imx/ipuv3/imx-drm-core.c | 4 +++-
>>>>     2 files changed, 8 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/drm_gem_dma_helper.c b/drivers/gpu/drm/
>>>> drm_gem_dma_helper.c
>>>> index 4f0320df858f..ab1a70b1d6f1 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;
>>> Hi,
>>>
>>> Was it intentional for this change to alter the pitch?
>> Most hardware does not need the pitch to be of a certain alignment. But
>> these buffers are possibly shared with other hardware, which sometimes
>> needs alignment to certain values. Using SZ_8 improves compatible with
>> that hardware.
>>
>>> The alignment requirement has been updated—from 8-bit alignment to
>>> 64-bit alignment. Since the pitch is expressed in bytes, we should pass
>>> SZ_1 instead of SZ_8 for hw_patch_align.
>>>
>>> For example, for an 850×480 framebuffer at 16 bpp, the pitch should be
>>> 1700 bytes. With the new alignment, the pitch becomes 1704 bytes.
>> Many display modes have an 8-byte alignment in their width. 850 pixels
>> is somewhat of an exception.
> Indeed, but overlay-type planes are often used to display windows that
> are not the same size as the screen, and therefore potentially not on
> 8-bytes aligned.
>
>>> Please let me know if you’d like me to submit a fix.
>> Do you see a bug with your hardware? Unless this creates a real problem,
>> I'd like to keep it as it is now.
> Yes, that’s how I noticed this change. I have an application that
> requests a framebuffer larger than my screen, in this case 850x480 in
> RGB565 for an 800x480 display. So I have a pitch of 1700 bytes. Now it’s
> using a pitch of 1704, which shifts my lines.

Honestly, your application is broken. The ioctl returns the pitch value 
to user space and that's what the program should use. Some hardware has 
hard constraints on the pitch, so you will sooner or later run into the 
same problem again.

Anyway, feel free to submit a patch to call drm_mode_size_dumb() without 
SZ_8. The best value would be 0, so that the function picks a default by 
itself. Since you're at it, maybe also look at patches 4 and 5 of this 
series. They have similar code for other memory managers.

Best regards
Thomas

>
> Regards,
> Ludovic
>
>> Best regards
>> Thomas
>>
>>> Regards,
>>> Ludovic
>>>
>>>
>>>>       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..af4a30311e18 100644
>>>> --- a/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c
>>>> +++ b/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c
>>>> @@ -145,8 +145,10 @@ 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);
>>>> +    ret = drm_gem_dma_dumb_create_internal(file_priv, drm, args);
>>>>       if (ret)
>>>>               return ret;
>>>>
>> -- 
>> -- 
>> Thomas Zimmermann
>> Graphics Driver Developer
>> SUSE Software Solutions Germany GmbH
>> Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
>> GF: Jochen Jaser, Andrew McDonald, Werner Knoblich, (HRB 36809, AG
>> Nürnberg)
>>
>>
>

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
GF: Jochen Jaser, Andrew McDonald, Werner Knoblich, (HRB 36809, AG Nürnberg)

Re: [PATCH v6 03/25] drm/gem-dma: Compute dumb-buffer sizes with drm_mode_size_dumb()

[Ludovic.Desroches]

On 11/26/25 08:40, Thomas Zimmermann wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know 
> the content is safe
> 
> Hi
> 
> Am 26.11.25 um 07:24 schrieb Ludovic.Desroches@microchip.com:
>> On 11/25/25 16:03, Thomas Zimmermann wrote:
>>> EXTERNAL EMAIL: Do not click links or open attachments unless you know
>>> the content is safe
>>>
>>> Hi
>>>
>>> Am 25.11.25 um 15:39 schrieb Ludovic.Desroches@microchip.com:
>>>> On 8/21/25 10:17, 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.
>>> I missed a chance to explain it here. :/
>> I was wondering if it was 8-bits or 8-bytes.
>>
>>>>> 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.
>>>>>
>>>>> v5:
>>>>> - avoid reset of arguments (Tomi)
>>>>>
>>>>> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
>>>>> Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
>>>>> ---
>>>>>     drivers/gpu/drm/drm_gem_dma_helper.c     | 7 +++++--
>>>>>     drivers/gpu/drm/imx/ipuv3/imx-drm-core.c | 4 +++-
>>>>>     2 files changed, 8 insertions(+), 3 deletions(-)
>>>>>
>>>>> diff --git a/drivers/gpu/drm/drm_gem_dma_helper.c b/drivers/gpu/drm/
>>>>> drm_gem_dma_helper.c
>>>>> index 4f0320df858f..ab1a70b1d6f1 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;
>>>> Hi,
>>>>
>>>> Was it intentional for this change to alter the pitch?
>>> Most hardware does not need the pitch to be of a certain alignment. But
>>> these buffers are possibly shared with other hardware, which sometimes
>>> needs alignment to certain values. Using SZ_8 improves compatible with
>>> that hardware.
>>>
>>>> The alignment requirement has been updated—from 8-bit alignment to
>>>> 64-bit alignment. Since the pitch is expressed in bytes, we should pass
>>>> SZ_1 instead of SZ_8 for hw_patch_align.
>>>>
>>>> For example, for an 850×480 framebuffer at 16 bpp, the pitch should be
>>>> 1700 bytes. With the new alignment, the pitch becomes 1704 bytes.
>>> Many display modes have an 8-byte alignment in their width. 850 pixels
>>> is somewhat of an exception.
>> Indeed, but overlay-type planes are often used to display windows that
>> are not the same size as the screen, and therefore potentially not on
>> 8-bytes aligned.
>>
>>>> Please let me know if you’d like me to submit a fix.
>>> Do you see a bug with your hardware? Unless this creates a real problem,
>>> I'd like to keep it as it is now.
>> Yes, that’s how I noticed this change. I have an application that
>> requests a framebuffer larger than my screen, in this case 850x480 in
>> RGB565 for an 800x480 display. So I have a pitch of 1700 bytes. Now it’s
>> using a pitch of 1704, which shifts my lines.
> 
> Honestly, your application is broken. The ioctl returns the pitch value
> to user space and that's what the program should use. Some hardware has
> hard constraints on the pitch, so you will sooner or later run into the
> same problem again.

Yes, I’m currently trying to find where the pitch information is being 
lost, given that we do correctly retrieve the value provided by the 
kernel after the ioctl.

> 
> Anyway, feel free to submit a patch to call drm_mode_size_dumb() without
> SZ_8. The best value would be 0, so that the function picks a default by
> itself. Since you're at it, maybe also look at patches 4 and 5 of this
> series. They have similar code for other memory managers.

I have no strong opinion about this 8-bytes alignment if it was 
intended. This could potentially break other applications that had been 
working until now, even if it does indeed reveal an issue on the 
application side. And it can result in larger buffers without it 
necessarily being needed.

I'll prepare patches and we'll see where that leads.

Regards,
Ludovic

> 
> Best regards
> Thomas
> 
>>
>> Regards,
>> Ludovic
>>
>>> Best regards
>>> Thomas
>>>
>>>> Regards,
>>>> Ludovic
>>>>
>>>>
>>>>>       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..af4a30311e18 100644
>>>>> --- a/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c
>>>>> +++ b/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c
>>>>> @@ -145,8 +145,10 @@ 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);
>>>>> +    ret = drm_gem_dma_dumb_create_internal(file_priv, drm, args);
>>>>>       if (ret)
>>>>>               return ret;
>>>>>
>>> -- 
>>> -- 
>>> Thomas Zimmermann
>>> Graphics Driver Developer
>>> SUSE Software Solutions Germany GmbH
>>> Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
>>> GF: Jochen Jaser, Andrew McDonald, Werner Knoblich, (HRB 36809, AG
>>> Nürnberg)
>>>
>>>
>>
> 
> -- 
> -- 
> Thomas Zimmermann
> Graphics Driver Developer
> SUSE Software Solutions Germany GmbH
> Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
> GF: Jochen Jaser, Andrew McDonald, Werner Knoblich, (HRB 36809, AG 
> Nürnberg)
> 
> 

[PATCH v6 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>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
---
 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 5d1349c34afd..b90096ad82d8 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>
@@ -518,18 +519,11 @@ EXPORT_SYMBOL_GPL(drm_gem_shmem_purge_locked);
 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);
 }
-- 
2.50.1

[PATCH v6 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 b04cde4a60e7..dd4537bf63dc 100644
--- a/drivers/gpu/drm/drm_gem_vram_helper.c
+++ b/drivers/gpu/drm/drm_gem_vram_helper.c
@@ -7,6 +7,7 @@
 #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>
@@ -545,10 +546,31 @@ 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);
 
-- 
2.50.1

[PATCH v6 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;
-- 
2.50.1

[PATCH v6 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>
Acked-by: Inki Dae <inki.dae@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 e3fbb45f37a2..02714c9ab639 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_gem.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_gem.c
@@ -10,6 +10,7 @@
 #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>
@@ -329,15 +330,16 @@ 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
-- 
2.50.1

[PATCH v6 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:
-- 
2.50.1

[PATCH v6 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 dd4537bf63dc..d5a6d5134c55 100644
--- a/drivers/gpu/drm/drm_gem_vram_helper.c
+++ b/drivers/gpu/drm/drm_gem_vram_helper.c
@@ -407,71 +407,6 @@ 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 289304500ab0..14a018c47c73 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>
 
@@ -70,7 +72,28 @@ static irqreturn_t hibmc_dp_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 2dd42bed679d..1190064f5760 100644
--- a/include/drm/drm_gem_vram_helper.h
+++ b/include/drm/drm_gem_vram_helper.h
@@ -98,12 +98,6 @@ 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
  */
-- 
2.50.1

[PATCH v6 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 to be large enough to support
this. Therefore compute the byte size of 8 pixels in the given color
mode and align the pitch accordingly.

v5:
- fix typo in commit description

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 af4a30311e18..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_internal(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 = {
-- 
2.50.1

[PATCH v6 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;
 }
 
-- 
2.50.1

[PATCH v6 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))
-- 
2.50.1

[PATCH v6 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 7ff994d4f91a..d854444ba1b5 100644
--- a/drivers/gpu/drm/msm/msm_gem.c
+++ b/drivers/gpu/drm/msm/msm_gem.c
@@ -10,8 +10,10 @@
 #include <linux/shmem_fs.h>
 #include <linux/dma-buf.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>
 
@@ -691,8 +693,29 @@ void msm_gem_unpin_iova(struct drm_gem_object *obj, struct drm_gpuvm *vm)
 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");
 }
-- 
2.50.1

Re: [PATCH v6 13/25] drm/msm: Compute dumb-buffer sizes with drm_mode_size_dumb()

[Dmitry Baryshkov]

On Thu, Aug 21, 2025 at 10:17:20AM +0200, Thomas Zimmermann wrote:
> 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(-)
> 

This broke kms_getfb@getfb-reject-nv12 and kms_getfb@getfb2-accept-nv12
IGT tests. I'll submit a fix separately.

-- 
With best wishes
Dmitry

[PATCH v6 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 805d0a87aa54..54aed3656a4c 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>
@@ -807,9 +808,9 @@ 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)
-- 
2.50.1

[PATCH v6 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 381552bfb409..78563a8d8732 100644
--- a/drivers/gpu/drm/omapdrm/omap_gem.c
+++ b/drivers/gpu/drm/omapdrm/omap_gem.c
@@ -10,6 +10,7 @@
 #include <linux/spinlock.h>
 #include <linux/vmalloc.h>
 
+#include <drm/drm_dumb_buffers.h>
 #include <drm/drm_prime.h>
 #include <drm/drm_vma_manager.h>
 
@@ -580,15 +581,13 @@ 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);
-- 
2.50.1

[PATCH v6 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;
 }
-- 
2.50.1

[PATCH v6 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>
Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen+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 216219accfd9..6294443f6068 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);
 }
-- 
2.50.1

[PATCH v6 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.

v5:
- include dumb-buffers header for drm_mode_size_dumb() (kernel test robot)

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 | 8 +++++---
 1 file changed, 5 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 87f171145a23..5fcade2b6054 100644
--- a/drivers/gpu/drm/renesas/rz-du/rzg2l_du_kms.c
+++ b/drivers/gpu/drm/renesas/rz-du/rzg2l_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>
@@ -181,10 +182,11 @@ 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);
 }
-- 
2.50.1

RE: [PATCH v6 18/25] drm/renesas/rz-du: Compute dumb-buffer sizes with drm_mode_size_dumb()

[Biju Das]

Hi Thomas Zimmermann,

Thanks for the patch.

> -----Original Message-----
> From: Thomas Zimmermann <tzimmermann@suse.de>
> Sent: 21 August 2025 09:17
> Subject: [PATCH v6 18/25] drm/renesas/rz-du: Compute dumb-buffer sizes with drm_mode_size_dumb()
> 
> Call drm_mode_size_dumb() to compute dumb-buffer scanline pitch and buffer size. Align the pitch
> according to hardware requirements.
> 
> v5:
> - include dumb-buffers header for drm_mode_size_dumb() (kernel test robot)
> 
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> Cc: Biju Das <biju.das.jz@bp.renesas.com>

Tested-by: Biju Das <biju.das.jz@bp.renesas.com>

Cheers,
Biju

Re: [PATCH v6 18/25] drm/renesas/rz-du: Compute dumb-buffer sizes with drm_mode_size_dumb()

[Thomas Zimmermann]

Hi

Am 21.08.25 um 13:28 schrieb Biju Das:
> Hi Thomas Zimmermann,
>
> Thanks for the patch.
>
>> -----Original Message-----
>> From: Thomas Zimmermann <tzimmermann@suse.de>
>> Sent: 21 August 2025 09:17
>> Subject: [PATCH v6 18/25] drm/renesas/rz-du: Compute dumb-buffer sizes with drm_mode_size_dumb()
>>
>> Call drm_mode_size_dumb() to compute dumb-buffer scanline pitch and buffer size. Align the pitch
>> according to hardware requirements.
>>
>> v5:
>> - include dumb-buffers header for drm_mode_size_dumb() (kernel test robot)
>>
>> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
>> Cc: Biju Das <biju.das.jz@bp.renesas.com>
> Tested-by: Biju Das <biju.das.jz@bp.renesas.com>

Thanks for testing. Could you also review the patch, please?

Best regards
Thomas

>
> Cheers,
> Biju

-- 
--
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)

RE: [PATCH v6 18/25] drm/renesas/rz-du: Compute dumb-buffer sizes with drm_mode_size_dumb()

[Biju Das]

Hi Thomas,

> -----Original Message-----
> From: Thomas Zimmermann <tzimmermann@suse.de>
> Sent: 21 August 2025 12:56
> Subject: Re: [PATCH v6 18/25] drm/renesas/rz-du: Compute dumb-buffer sizes with drm_mode_size_dumb()
> 
> Hi
> 
> Am 21.08.25 um 13:28 schrieb Biju Das:
> > Hi Thomas Zimmermann,
> >
> > Thanks for the patch.
> >
> >> -----Original Message-----
> >> From: Thomas Zimmermann <tzimmermann@suse.de>
> >> Sent: 21 August 2025 09:17
> >> Subject: [PATCH v6 18/25] drm/renesas/rz-du: Compute dumb-buffer
> >> sizes with drm_mode_size_dumb()
> >>
> >> Call drm_mode_size_dumb() to compute dumb-buffer scanline pitch and
> >> buffer size. Align the pitch according to hardware requirements.
> >>
> >> v5:
> >> - include dumb-buffers header for drm_mode_size_dumb() (kernel test
> >> robot)
> >>
> >> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> >> Cc: Biju Das <biju.das.jz@bp.renesas.com>
> > Tested-by: Biju Das <biju.das.jz@bp.renesas.com>
> 
> Thanks for testing. Could you also review the patch, please?

Sure, will do.

Cheers,
Biju

[PATCH v6 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);
-- 
2.50.1

[PATCH v6 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 41a285ec889f..84719c9d8720 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.h"
@@ -542,12 +543,13 @@ 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);
-- 
2.50.1

[PATCH v6 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 90c99d83c4cf..7e515d6e781d 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:
-- 
2.50.1

[PATCH v6 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 7e281c3c6bc5..c4ac9b47e23a 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)
@@ -2267,23 +2268,9 @@ 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,
-- 
2.50.1

[PATCH v6 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 6fea39842e1e..2be7a618165a 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>
@@ -3130,14 +3131,13 @@ 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,
-- 
2.50.1

Re: [PATCH v6 23/25] drm/xe: Compute dumb-buffer sizes with drm_mode_size_dumb()

[Lucas De Marchi]

On Thu, Aug 21, 2025 at 10:17:30AM +0200, 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. 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>

Acked-by: Lucas De Marchi <lucas.demarchi@intel.com>

to merge this via drm-misc.

thanks
Lucas De Marchi

>---
> 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 6fea39842e1e..2be7a618165a 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>
>@@ -3130,14 +3131,13 @@ 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,
>-- 
>2.50.1
>

[PATCH v6 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)) {
-- 
2.50.1

[PATCH v6 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>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: 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 2bee0a2275ed..02f3a7d78cf8 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);
 }
-- 
2.50.1

Re: [PATCH v6 00/25] drm/dumb-buffers: Fix and improve buffer-size calculation

[Thomas Zimmermann]

FYI, I significant number of these patches got a review already. I 
intent to merge these and then send out the others for each driver 
individually.

Am 21.08.25 um 10:17 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.
>
> v6:
> - extend TODO item (Tomi)
> - fix typos in documentation (Tomi)
> v5:
> - use check_mul_overflow() for overflow test (Tomi)
> - imx: fix intermediate code (Tomi)
> - rz-du: include dumb-buffers header
> 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                    |  37 ++++
>   drivers/gpu/drm/armada/armada_gem.c           |  16 +-
>   drivers/gpu/drm/drm_dumb_buffers.c            | 170 ++++++++++++++++--
>   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  |   8 +-
>   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, 457 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)