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 tires 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.
Signed-off-by: Stefan Agner <[email protected]>
---
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 8c549c3931af..fa6798d21029 100644
--- a/drivers/gpu/drm/mxsfb/mxsfb_drv.c
+++ b/drivers/gpu/drm/mxsfb/mxsfb_drv.c
@@ -21,6 +21,7 @@
#include <drm/drm_connector.h>
#include <drm/drm_drv.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>
@@ -81,8 +82,26 @@ 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,
};
--
2.28.0
Hi Stefan,
Thank you for the patch.
On Tue, Sep 08, 2020 at 02:55:58PM +0200, Stefan Agner wrote:
> 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 tires to use a cache aligned stride, which
Still s/tires/tries/ :-)
> 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.
>
> Signed-off-by: Stefan Agner <[email protected]>
Reviewed-by: Laurent Pinchart <[email protected]>
> ---
> 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 8c549c3931af..fa6798d21029 100644
> --- a/drivers/gpu/drm/mxsfb/mxsfb_drv.c
> +++ b/drivers/gpu/drm/mxsfb/mxsfb_drv.c
> @@ -21,6 +21,7 @@
> #include <drm/drm_connector.h>
> #include <drm/drm_drv.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>
> @@ -81,8 +82,26 @@ 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,
> };
--
Regards,
Laurent Pinchart
Hi Stefan,
On Tue, Sep 8, 2020 at 9:56 AM Stefan Agner <[email protected]> wrote:
>
> 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 tires 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.
What about adding a Fixes tag so that it can be backported to old
stable kernels?
Thanks