[PATCH 5/8] drm/exynos: introduce BYTE_PITCH capability

[Inki Dae]

2017년 08월 09일 20:48에 Tobias Jakobi 이(가) 쓴 글:
> In some of drivers 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 is not always true, in particular
> DRM core does not check for pitch alignment in the common case.
> 
> 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 pitch aligned to cpp.
> 
> We set this cap later for the drivers/planes that support it.
> 
> Signed-off-by: Tobias Jakobi <tjakobi at math.uni-bielefeld.de>
> ---
>  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)

I don't see why this flag is required because cpp value is given always. So I think we can check the pitch alignment regardless of a given flag.
BTW, it'd better for pitch alignment to be checked by drm core?

>  
>  /*
>   * 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 bd3825617b06..734d5ba4eb99 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))
>