[PATCH v2 6/9] drm/exynos: introduce BYTE_PITCH capability

[Tobias Jakobi]

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 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)
 
 /*
  * 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))
-- 
2.13.0