[PATCH v3 03/25] drm/gem-dma: Compute dumb-buffer sizes with drm_mode_size_dumb()

Thomas Zimmermann
2025-02-18T14:26:49Z

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

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

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

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

diff --git a/drivers/gpu/drm/drm_gem_dma_helper.c b/drivers/gpu/drm/drm_gem_dma_helper.c
index 16988d316a6d..5bca7ce3683f 100644
--- a/drivers/gpu/drm/drm_gem_dma_helper.c
+++ b/drivers/gpu/drm/drm_gem_dma_helper.c
@@ -20,6 +20,7 @@
#include <drm/drm.h>
#include <drm/drm_device.h>
#include <drm/drm_drv.h>
+#include <drm/drm_dumb_buffers.h>
#include <drm/drm_gem_dma_helper.h>
#include <drm/drm_vma_manager.h>

@@ -304,9 +305,11 @@ int drm_gem_dma_dumb_create(struct drm_file *file_priv,
struct drm_mode_create_dumb *args)
{
struct drm_gem_dma_object *dma_obj;
+ int ret;

- args->pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
- args->size = args->pitch * args->height;
+ ret = drm_mode_size_dumb(drm, args, SZ_8, 0);
+ if (ret)
+ return ret;

dma_obj = drm_gem_dma_create_with_handle(file_priv, drm, args->size,
&args->handle);
diff --git a/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c b/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c
index ec5fd9a01f1e..e7025df7b978 100644
--- a/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c
+++ b/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c
@@ -145,6 +145,8 @@ static int imx_drm_dumb_create(struct drm_file *file_priv,
int ret;

args->width = ALIGN(width, 8);
+ args->pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
+ args->size = args->pitch * args->height;

ret = drm_gem_dma_dumb_create(file_priv, drm, args);
if (ret)