While running v4l2-compliance tests on vivid I suddenly got errors due to
a call to vmalloc_user with size 0 from vb2.
Digging deeper into the cause I discovered that this was due to the fact that
struct v4l2_plane_pix_format defines bytesperline as a __u16 instead of a __u32.
The test I was running selected a format of 4 * 4096 by 4 * 2048 with a 32
bit pixelformat.
So bytesperline was 4 * 4 * 4096 = 65536, which becomes 0 in a __u16. And
bytesperline * height is suddenly 0 as well.
The best approach IMHO is to increase the type to __u32. The only drivers
besides vivid that use the multiplanar API are little-endian ARM and SH platforms
(exynos, ti-vpe, vsp1).
Does anyone know of someone using those drivers on a big-endian system?
I don't think we can ignore this. With work going on for deep-color and 8K formats
you can reach this limit already (8192 * 8 == 65536). Ditto for high-resolution
sensors. Add a scaler in the mix (like the vivid driver does) and you reach the
limit very quickly.
The alternative would be to add a __u32 bytesperline_msb field, but I think
we can still safely change the API today without adding a cumbersome msb field.
Comments?
Hans
Signed-off-by: Hans Verkuil <hans.verkuil@xxxxxxxxx>
---
diff --git a/Documentation/DocBook/media/v4l/pixfmt.xml b/Documentation/DocBook/media/v4l/pixfmt.xml
index 13540fa..35d2f86 100644
--- a/Documentation/DocBook/media/v4l/pixfmt.xml
+++ b/Documentation/DocBook/media/v4l/pixfmt.xml
@@ -182,14 +182,14 @@ see <xref linkend="colorspaces" />.</entry>
</entry>
</row>
<row>
- <entry>__u16</entry>
+ <entry>__u32</entry>
<entry><structfield>bytesperline</structfield></entry>
<entry>Distance in bytes between the leftmost pixels in two adjacent
lines. See &v4l2-pix-format;.</entry>
</row>
<row>
<entry>__u16</entry>
- <entry><structfield>reserved[7]</structfield></entry>
+ <entry><structfield>reserved[6]</structfield></entry>
<entry>Reserved for future extensions. Should be zeroed by the
application.</entry>
</row>
diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
index fbdc360..44f381d 100644
--- a/include/uapi/linux/videodev2.h
+++ b/include/uapi/linux/videodev2.h
@@ -1841,8 +1841,8 @@ struct v4l2_mpeg_vbi_fmt_ivtv {
*/
struct v4l2_plane_pix_format {
__u32 sizeimage;
- __u16 bytesperline;
- __u16 reserved[7];
+ __u32 bytesperline;
+ __u16 reserved[6];
} __attribute__ ((packed));
/**
--
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