[PATCH 5.8 224/633] drm: mxsfb: check framebuffer pitch

Greg Kroah-Hartman
2020-10-27T15:01:24Z

From: Stefan Agner <stefan@agner.ch>

[ Upstream commit d5a0c816900419105a12e7471bf074319dfa34be ]

The lcdif IP does not support a framebuffer pitch (stride) other than
framebuffer width. Check for equality and reject the framebuffer
otherwise.

This prevents a distorted picture when using 640x800 and running the
Mesa graphics stack. Mesa tries to use a cache aligned stride, which
leads at that particular resolution to width != stride. Currently
Mesa has no fallback behavior, but rejecting this configuration allows
userspace to handle the issue correctly.

Fixes: 45d59d704080 ("drm: Add new driver for MXSFB controller")
Signed-off-by: Stefan Agner <stefan@agner.ch>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200908141654.266836-1-stefan@agner.ch
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpu/drm/mxsfb/mxsfb_drv.c | 21 ++++++++++++++++++++-
1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/mxsfb/mxsfb_drv.c b/drivers/gpu/drm/mxsfb/mxsfb_drv.c
index 497cf443a9afa..0b02e65a89e79 100644
--- a/drivers/gpu/drm/mxsfb/mxsfb_drv.c
+++ b/drivers/gpu/drm/mxsfb/mxsfb_drv.c
@@ -26,6 +26,7 @@
#include <drm/drm_drv.h>
#include <drm/drm_fb_cma_helper.h>
#include <drm/drm_fb_helper.h>
+#include <drm/drm_fourcc.h>
#include <drm/drm_gem_cma_helper.h>
#include <drm/drm_gem_framebuffer_helper.h>
#include <drm/drm_irq.h>
@@ -87,8 +88,26 @@ void mxsfb_disable_axi_clk(struct mxsfb_drm_private *mxsfb)
clk_disable_unprepare(mxsfb->clk_axi);
}

+static struct drm_framebuffer *
+mxsfb_fb_create(struct drm_device *dev, struct drm_file *file_priv,
+ const struct drm_mode_fb_cmd2 *mode_cmd)
+{
+ const struct drm_format_info *info;
+
+ info = drm_get_format_info(dev, mode_cmd);
+ if (!info)
+ return ERR_PTR(-EINVAL);
+
+ if (mode_cmd->width * info->cpp[0] != mode_cmd->pitches[0]) {
+ dev_dbg(dev->dev, "Invalid pitch: fb width must match pitch\n");
+ return ERR_PTR(-EINVAL);
+ }
+
+ return drm_gem_fb_create(dev, file_priv, mode_cmd);
+}
+
static const struct drm_mode_config_funcs mxsfb_mode_config_funcs = {
- .fb_create = drm_gem_fb_create,
+ .fb_create = mxsfb_fb_create,
.atomic_check = drm_atomic_helper_check,
.atomic_commit = drm_atomic_helper_commit,
};
--
2.25.1