Commit 2dab0bab authored Sep 25, 2014 by Tomi Valkeinen

drm/omap: handle incompatible buffer stride and pixel size



omapdrm doesn't check if the pitch of the framebuffer and the color
format's bits-per-pixel are compatible. omapdss requires that the stride
of a buffer is an integer number of pixels

For example, when using modetest with a display that has x resolution of
1280, and using packed 24 RGB mode (3 bytes per pixel), modetest
allocates a buffer with a byte stride of 4 * 1280 = 5120. But 5120 / 3 =
1706.666... pixels, which causes wrong colors and a tilt on the screen.

Add a check into omapdrm to return an error if the user tries to use
such a combination.

Note: this is not a HW requirement at least for non-rotation use cases,
but a SW driver requirement. In the future we should study if also
rotation use cases are fine with any stride size, and if so, change the
driver to allow these strides.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

parent 925e4940

drivers/gpu/drm/omapdrm/omap_fb.c

+8 −0

Original line number	Diff line number	Diff line
		@@ -423,6 +423,14 @@ struct drm_framebuffer omap_framebuffer_init(struct drm_device dev,
		goto fail;
		}

		if (pitch % format->planes[i].stride_bpp != 0) {
		dev_err(dev->dev,
		"buffer pitch (%d bytes) is not a multiple of pixel size (%d bytes)\n",
		pitch, format->planes[i].stride_bpp);
		ret = -EINVAL;
		goto fail;
		}

		size = pitch * mode_cmd->height / format->planes[i].sub_y;

		if (size > (omap_gem_mmap_size(bos[i]) - mode_cmd->offsets[i])) {