[PATCH v4 04/22] drm: omapdrm: fb: Simplify mode command checks when creating framebuffer

[Laurent Pinchart]

The hardware requires all planes to have an identical pitch in number of
pixels. Given that all supported formats use the same number of bytes
per pixel in all planes, framebuffer creation checks can be simplified.
The implementations assumes that no format use more than two planes
which is true with the existing hardware.

Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen at ti.com>
---
Changes since v3:

- Remove pitch check already performed by the DRM core

Changes since v1:

- Clarify commit message and mention explicitly in the code that only
  one and two planes formats are supported.
- Rebase on top of the switch to drm_format_info()
---
 drivers/gpu/drm/omapdrm/omap_fb.c | 50 ++++++++++++++++++---------------------
 1 file changed, 23 insertions(+), 27 deletions(-)

diff --git a/drivers/gpu/drm/omapdrm/omap_fb.c b/drivers/gpu/drm/omapdrm/omap_fb.c
index 195ab4c86244..016aac9a7731 100644
--- a/drivers/gpu/drm/omapdrm/omap_fb.c
+++ b/drivers/gpu/drm/omapdrm/omap_fb.c
@@ -387,6 +387,7 @@ struct drm_framebuffer *omap_framebuffer_init(struct drm_device *dev,
 	struct omap_framebuffer *omap_fb = NULL;
 	struct drm_framebuffer *fb = NULL;
 	enum omap_color_mode dss_format = 0;
+	unsigned int pitch = mode_cmd->pitches[0];
 	int ret, i;
 
 	DBG("create framebuffer: dev=%p, mode_cmd=%p (%dx%d@%4.4s)",
@@ -420,41 +421,36 @@ struct drm_framebuffer *omap_framebuffer_init(struct drm_device *dev,
 	omap_fb->dss_format = dss_format;
 	mutex_init(&omap_fb->lock);
 
+	/*
+	 * The code below assumes that no format use more than two planes, and
+	 * that the two planes of multiplane formats need the same number of
+	 * bytes per pixel.
+	 */
+	if (format->num_planes == 2 && pitch != mode_cmd->pitches[1]) {
+		dev_err(dev->dev, "pitches differ between planes 0 and 1\n");
+		ret = -EINVAL;
+		goto fail;
+	}
+
+	if (pitch % format->cpp[0]) {
+		dev_err(dev->dev,
+			"buffer pitch (%u bytes) is not a multiple of pixel size (%u bytes)\n",
+			pitch, format->cpp[0]);
+		ret = -EINVAL;
+		goto fail;
+	}
+
 	for (i = 0; i < format->num_planes; i++) {
 		struct plane *plane = &omap_fb->planes[i];
-		unsigned int pitch = mode_cmd->pitches[i];
-		unsigned int hsub = i == 0 ? 1 : format->hsub;
 		unsigned int vsub = i == 0 ? 1 : format->vsub;
 		unsigned int size;
 
-		if (pitch < mode_cmd->width * format->cpp[i] / hsub) {
-			dev_err(dev->dev, "provided buffer pitch is too small! %d < %d\n",
-				pitch, mode_cmd->width * format->cpp[i] / hsub);
-			ret = -EINVAL;
-			goto fail;
-		}
-
-		if (pitch % format->cpp[i] != 0) {
-			dev_err(dev->dev,
-				"buffer pitch (%d bytes) is not a multiple of pixel size (%d bytes)\n",
-				pitch, format->cpp[i]);
-			ret = -EINVAL;
-			goto fail;
-		}
-
 		size = pitch * mode_cmd->height / vsub;
 
-		if (size > (omap_gem_mmap_size(bos[i]) - mode_cmd->offsets[i])) {
-			dev_err(dev->dev, "provided buffer object is too small! %d < %d\n",
-					bos[i]->size - mode_cmd->offsets[i], size);
-			ret = -EINVAL;
-			goto fail;
-		}
-
-		if (i > 0 && pitch != mode_cmd->pitches[i - 1]) {
+		if (size > omap_gem_mmap_size(bos[i]) - mode_cmd->offsets[i]) {
 			dev_err(dev->dev,
-				"pitches are not the same between framebuffer planes %d != %d\n",
-				pitch, mode_cmd->pitches[i - 1]);
+				"provided buffer object is too small! %d < %d\n",
+				bos[i]->size - mode_cmd->offsets[i], size);
 			ret = -EINVAL;
 			goto fail;
 		}
-- 
Regards,

Laurent Pinchart