[PATCH 4/6] drm/msm: fbdev: Calculate buffer geometry with format helpers

Thomas Zimmermann
2026-04-21T12:57:48Z

Replace the geometry and size calculation in msm's fbdev emulation
with DRM format helpers. This consists of a 4CC lookup from the fbdev
parameters, format lookup, pitch calculation and size calculation.
Then allocate the GEM buffer object for the framebuffer memory from
the calculated size.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
drivers/gpu/drm/msm/msm_drv.h | 7 -------
drivers/gpu/drm/msm/msm_fbdev.c | 26 ++++++++++++--------------
2 files changed, 12 insertions(+), 21 deletions(-)

diff --git a/drivers/gpu/drm/msm/msm_drv.h b/drivers/gpu/drm/msm/msm_drv.h
index b3173fa4d222..00c50d7437d6 100644
--- a/drivers/gpu/drm/msm/msm_drv.h
+++ b/drivers/gpu/drm/msm/msm_drv.h
@@ -509,13 +509,6 @@ void msm_hrtimer_work_init(struct msm_hrtimer_work *work,
#define DBG(fmt, ...) DRM_DEBUG_DRIVER(fmt"\n", ##__VA_ARGS__)
#define VERB(fmt, ...) if (0) DRM_DEBUG_DRIVER(fmt"\n", ##__VA_ARGS__)

-static inline int align_pitch(int width, int bpp)
-{
- int bytespp = (bpp + 7) / 8;
- /* adreno needs pitch aligned to 32 pixels: */
- return bytespp * ALIGN(width, 32);
-}
-
/* for the generated headers: */
#define INVALID_IDX(idx) ({BUG(); 0;})
#define fui(x) ({BUG(); 0;})
diff --git a/drivers/gpu/drm/msm/msm_fbdev.c b/drivers/gpu/drm/msm/msm_fbdev.c
index 1eb0368a6d07..5532c5779f17 100644
--- a/drivers/gpu/drm/msm/msm_fbdev.c
+++ b/drivers/gpu/drm/msm/msm_fbdev.c
@@ -95,23 +95,25 @@ int msm_fbdev_driver_fbdev_probe(struct drm_fb_helper *helper,
struct fb_info *fbi = helper->info;
struct drm_mode_fb_cmd2 mode_cmd = { };
struct drm_framebuffer *fb = NULL;
+ const struct drm_format_info *format;
+ u32 fourcc, pitch;
+ u64 size;
struct drm_gem_object *bo;
uint64_t paddr;
- uint32_t format;
- int ret, pitch;
- int size;
-
- format = drm_mode_legacy_fb_format(sizes->surface_bpp, sizes->surface_depth);
+ int ret;

DBG("create fbdev: %dx%d@%d (%dx%d)", sizes->surface_width,
sizes->surface_height, sizes->surface_bpp,
sizes->fb_width, sizes->fb_height);

- pitch = align_pitch(sizes->surface_width, sizes->surface_bpp);
+ fourcc = drm_mode_legacy_fb_format(sizes->surface_bpp, sizes->surface_depth);
+ format = drm_get_format_info(dev, fourcc, DRM_FORMAT_MOD_LINEAR);
+ /* adreno needs pitch aligned to 32 pixels: */
+ pitch = drm_format_info_min_pitch(format, 0, ALIGN(sizes->surface_width, 32));
+ size = ALIGN(pitch * sizes->surface_height, PAGE_SIZE);

/* allocate backing bo */
- size = pitch * sizes->surface_height;
- DBG("allocating %d bytes for fb %d", size, dev->primary->index);
+ DBG("allocating %llu bytes for fb %d", size, dev->primary->index);
bo = msm_gem_new(dev, size, MSM_BO_SCANOUT | MSM_BO_WC | MSM_BO_STOLEN);
if (IS_ERR(bo)) {
drm_warn(dev, "could not allocate stolen bo\n");
@@ -125,16 +127,12 @@ int msm_fbdev_driver_fbdev_probe(struct drm_fb_helper *helper,

msm_gem_object_set_name(bo, "stolenfb");

- mode_cmd.pixel_format = format;
+ mode_cmd.pixel_format = fourcc;
mode_cmd.width = sizes->surface_width;
mode_cmd.height = sizes->surface_height;
mode_cmd.pitches[0] = pitch;
- mode_cmd.modifier[0] = DRM_FORMAT_MOD_LINEAR;

- fb = msm_framebuffer_init(dev,
- drm_get_format_info(dev, mode_cmd.pixel_format,
- mode_cmd.modifier[0]),
- &mode_cmd, &bo);
+ fb = msm_framebuffer_init(dev, format, &mode_cmd, &bo);
if (IS_ERR(fb)) {
drm_err(dev, "failed to allocate fb\n");
ret = PTR_ERR(fb);
--
2.53.0