[PATCH] drm/bridge: anx7625: Fix invalid EDID size

[Loic Poulain]

Hi Maxime,

On Mon, Jun 30, 2025 at 9:07 AM Maxime Ripard <mripard at kernel.org> wrote:
> On Sun, Jun 29, 2025 at 04:38:36AM +0200, Loic Poulain wrote:
> > DRM checks EDID block count against allocated size in drm_edid_valid
> > function. We have to allocate the right EDID size instead of the max
> > size to prevent the EDID to be reported as invalid.
> >
> > Fixes: 7c585f9a71aa ("drm/bridge: anx7625: use struct drm_edid more")
> > Signed-off-by: Loic Poulain <loic.poulain at oss.qualcomm.com>
> > ---
> >  drivers/gpu/drm/bridge/analogix/anx7625.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/bridge/analogix/anx7625.c b/drivers/gpu/drm/bridge/analogix/anx7625.c
> > index 8a9079c2ed5c..5a81d1bfc815 100644
> > --- a/drivers/gpu/drm/bridge/analogix/anx7625.c
> > +++ b/drivers/gpu/drm/bridge/analogix/anx7625.c
> > @@ -1801,7 +1801,7 @@ static const struct drm_edid *anx7625_edid_read(struct anx7625_data *ctx)
> >               return NULL;
> >       }
> >
> > -     ctx->cached_drm_edid = drm_edid_alloc(edid_buf, FOUR_BLOCK_SIZE);
> > +     ctx->cached_drm_edid = drm_edid_alloc(edid_buf, edid_num * ONE_BLOCK_SIZE);
> >       kfree(edid_buf);
>
> Do we need to cache the whole EDIDs? AFAIU, it's only ever used to get
> the manufacturer name, which fits into a u32 / 4 u8. We should probably
> just cache that.

While the cached EDID is indeed used internally to retrieve the
product ID, its content is also returned via the DRM read_edid
callback. This value is then used by the DRM core to enumerate
available display modes, and likely also when reading EDID from sysfs.

Regards,
Loic