Hi Vishal,
On 04/12/2024 18:26, Sagar, Vishal wrote:
[AMD Official Use Only - AMD Internal Distribution Only]
Hi Tomi,
Thanks for the patch.
-----Original Message-----
From: Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx>
Sent: Wednesday, December 4, 2024 10:31 AM
To: Sagar, Vishal <vishal.sagar@xxxxxxx>; Klymenko, Anatoliy
<Anatoliy.Klymenko@xxxxxxx>; Maarten Lankhorst
<maarten.lankhorst@xxxxxxxxxxxxxxx>; Maxime Ripard <mripard@xxxxxxxxxx>;
Thomas Zimmermann <tzimmermann@xxxxxxx>; David Airlie
<airlied@xxxxxxxxx>; Simona Vetter <simona@xxxxxxxx>; Laurent Pinchart
<laurent.pinchart@xxxxxxxxxxxxxxxx>; Simek, Michal <michal.simek@xxxxxxx>
Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; linux-arm-
kernel@xxxxxxxxxxxxxxxxxxx; Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx>
Subject: [PATCH 01/10] drm/fourcc: Add warning for bad bpp
drm_format_info_bpp() cannot be used for formats which do not have an
integer bits-per-pixel. Handle wrong calls by printing a warning and
returning 0.
It would be good to add an example of pixel format that may cause this issue.
Indeed, the description is perhaps a bit lacking. I'll change it to:
drm_format_info_bpp() cannot be used for formats which do not have an
integer bits-per-pixel in a pixel block.
E.g. DRM_FORMAT_XV15's (not yet in upstream) plane 0 has three 10-bit
pixels (Y components), and two padding bits, in a 4 byte block. That is
10.666... bits per pixel when considering the whole 4 byte block, which
is what drm_format_info_bpp() does. Thus a driver that supports such
formats cannot use drm_format_info_bpp(),
It is a driver bug if this happens, but so handle wrong calls by
printing a warning and returning 0.
Tomi
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/drm_fourcc.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c
index 193cf8ed7912..e84c4ed6928c 100644
--- a/drivers/gpu/drm/drm_fourcc.c
+++ b/drivers/gpu/drm/drm_fourcc.c
@@ -429,6 +429,13 @@ unsigned int drm_format_info_bpp(const struct
drm_format_info *info, int plane)
if (!info || plane < 0 || plane >= info->num_planes)
return 0;
+ if (info->char_per_block[plane] * 8 %
+ (drm_format_info_block_width(info, plane) *
+ drm_format_info_block_height(info, plane))) {
+ pr_warn("unable to return an integer bpp\n");
+ return 0;
+ }
+
return info->char_per_block[plane] * 8 /
(drm_format_info_block_width(info, plane) *
drm_format_info_block_height(info, plane));
--
2.43.0
Regards
Vishal Sagar
