Hi Tobias, On 2017-08-22 16:19, Tobias Jakobi wrote:
In some of subdrivers we compute something like 'pitch / cpp' at some point, silently assuming that the pitch (which is in bytes) is divisible by the buffer's cpp. This must not be true, in particular it depends on the underlying hardware. If userspace should request such a setup, we should communicate this. Introduce a new cap which indicates that the hardware supports a pitch with 'byte-granularity'. If the cap is not set, assume that we need a pitch aligned to cpp. We set this cap in a later patch for the drivers/planes which support it. Signed-off-by: Tobias Jakobi <tjakobi@xxxxxxxxxxxxxxxxxxxxx>
I briefly checked the patch and it looks fine, but I really wonder whether drivers should support such strange formats, when pitches are not multiple of pixel size in bytes. I cannot find any sane use case for such formats. Maybe it would make sense to add a check for it in DRM core? I also didn't notice a check for that in any other drivers, but some of them also compute 'pitch / cpp' values.
--- drivers/gpu/drm/exynos/exynos_drm_drv.h | 1 + drivers/gpu/drm/exynos/exynos_drm_plane.c | 10 ++++++++++ 2 files changed, 11 insertions(+) diff --git a/drivers/gpu/drm/exynos/exynos_drm_drv.h b/drivers/gpu/drm/exynos/exynos_drm_drv.h index 43afab4bebc3..ec32632485d2 100644 --- a/drivers/gpu/drm/exynos/exynos_drm_drv.h +++ b/drivers/gpu/drm/exynos/exynos_drm_drv.h @@ -92,6 +92,7 @@ struct exynos_drm_plane { #define EXYNOS_DRM_PLANE_CAP_SCALE (1 << 1) #define EXYNOS_DRM_PLANE_CAP_ZPOS (1 << 2) #define EXYNOS_DRM_PLANE_CAP_TILE (1 << 3) +#define EXYNOS_DRM_PLANE_CAP_BYTE_PITCH (1 << 4)/** Exynos DRM plane configuration structure. diff --git a/drivers/gpu/drm/exynos/exynos_drm_plane.c b/drivers/gpu/drm/exynos/exynos_drm_plane.c index 133af72f5c90..17e47b8f0d6a 100644 --- a/drivers/gpu/drm/exynos/exynos_drm_plane.c +++ b/drivers/gpu/drm/exynos/exynos_drm_plane.c @@ -185,6 +185,16 @@ exynos_drm_plane_check_format(const struct exynos_drm_plane_config *config, { struct drm_framebuffer *fb = state->base.fb;+ /*+ * Some blocks only allow to specify a buffer pitch in terms + * of pixels. In these cases, we need to ensure that the pitch + * provided by userspace is divisible by the cpp. + */ + if (!(config->capabilities & EXYNOS_DRM_PLANE_CAP_BYTE_PITCH)) { + if (fb->pitches[0] % fb->format->cpp[0]) + return -ENOTSUPP; + } + switch (fb->modifier) { case DRM_FORMAT_MOD_SAMSUNG_64_32_TILE: if (!(config->capabilities & EXYNOS_DRM_PLANE_CAP_TILE))
Best regards -- Marek Szyprowski, PhD Samsung R&D Institute Poland -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
