Le 13/07/24 - 11:38, Maíra Canal a écrit :
> On 5/16/24 10:04, Louis Chauvet wrote:
> > Introduce two typedefs: pixel_read_t and pixel_write_t. It allows the
> > compiler to check if the passed functions take the correct arguments.
> > Such typedefs will help ensuring consistency across the code base in
> > case of update of these prototypes.
> >
> > Rename input/output variable in a consistent way between read_line and
> > write_line.
> >
> > A warn has been added in get_pixel_*_function to alert when an unsupported
> > pixel format is requested. As those formats are checked before
> > atomic_update callbacks, it should never happen.
> >
> > Document for those typedefs.
> >
> > Reviewed-by: Pekka Paalanen <pekka.paalanen@xxxxxxxxxxxxx>
> > Signed-off-by: Louis Chauvet <louis.chauvet@xxxxxxxxxxx>
[...]
> > /**
> > @@ -265,7 +265,7 @@ void vkms_writeback_row(struct vkms_writeback_job *wb,
> > *
> > * @format: DRM_FORMAT_* value for which to obtain a conversion function (see [drm_fourcc.h])
> > */
> > -void *get_pixel_conversion_function(u32 format)
> > +pixel_read_t get_pixel_read_function(u32 format)
> > {
> > switch (format) {
> > case DRM_FORMAT_ARGB8888:
> > @@ -279,7 +279,16 @@ void *get_pixel_conversion_function(u32 format)
> > case DRM_FORMAT_RGB565:
> > return &RGB565_to_argb_u16;
> > default:
> > - return NULL;
> > + /*
> > + * This is a bug in vkms_plane_atomic_check(). All the supported
> > + * format must:
> > + * - Be listed in vkms_formats in vkms_plane.c
> > + * - Have a pixel_read callback defined here
> > + */
> > + WARN(true,
> > + "Pixel format %p4cc is not supported by VKMS planes. This is a kernel bug, atomic check must forbid this configuration.\n",
> > + &format);
>
> Well, if this is a kernel bug, shouldn't we use a BUG_ON()/BUG() macro?
I don't know what is the "rule" for this kind of bug. Yes it is a kernel
bug, but it is recoverable and I can avoid a full kernel crash by using a
"do nothing" callback.
If you prefer I can replace this by:
pr_err("Pixel format %p4cc is [...]", &format);
BUG();
and drop the next commit. The kernel will crash if there is a mismatch
between advertised supported formats and formats listed here.
> Best Regards,
> - Maíra
>
> > * @format: DRM_FORMAT_* value for which to obtain a conversion function (see [drm_fourcc.h])
> > */
> > -void *get_pixel_write_function(u32 format)
> > +pixel_write_t get_pixel_write_function(u32 format)
> > {
> > switch (format) {
> > case DRM_FORMAT_ARGB8888:
> > @@ -304,6 +313,15 @@ void *get_pixel_write_function(u32 format)
> > case DRM_FORMAT_RGB565:
> > return &argb_u16_to_RGB565;
> > default:
> > - return NULL;
> > + /*
> > + * This is a bug in vkms_writeback_atomic_check. All the supported
> > + * format must:
> > + * - Be listed in vkms_wb_formats in vkms_writeback.c
> > + * - Have a pixel_write callback defined here
> > + */
> > + WARN(true,
> > + "Pixel format %p4cc is not supported by VKMS writeback. This is a kernel bug, atomic check must forbid this configuration.\n",
> > + &format);
> > + return (pixel_write_t)NULL;
I can do the same here.
Thanks,
Louis Chauvet
[...]
--
Louis Chauvet, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
