Hi, Angelo:
AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx> 於
2021年12月13日 週一 下午6:02寫道：
>
> Il 28/10/21 09:43, AngeloGioacchino Del Regno ha scritto:
> > In commit 41ca9caaae0b ("drm/mediatek: hdmi: Add check for CEA modes only")
> > a check for CEA modes was added to function mtk_hdmi_bridge_mode_valid()
> > in order to address possible issues on MT8167; moreover, with commit
> > c91026a938c2 ("drm/mediatek: hdmi: Add optional limit on maximal HDMI mode clock")
> > another similar check was introduced.
> >
> > Unfortunately though, at the time of writing, MT8173 does not provide
> > any mtk_hdmi_conf structure and this is crashing the kernel with NULL
> > pointer upon entering mtk_hdmi_bridge_mode_valid(), which happens as
> > soon as a HDMI cable gets plugged in.
> >
> > To fix this regression, add a NULL pointer check for hdmi->conf in the
> > said function, restoring HDMI functionality and avoiding NULL pointer
> > kernel panics.
> >
> > Fixes: 41ca9caaae0b ("drm/mediatek: hdmi: Add check for CEA modes only")
> > Fixes: c91026a938c2 ("drm/mediatek: hdmi: Add optional limit on maximal HDMI mode clock")
> > Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>
> > ---
> > drivers/gpu/drm/mediatek/mtk_hdmi.c | 12 +++++++-----
> > 1 file changed, 7 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/mediatek/mtk_hdmi.c b/drivers/gpu/drm/mediatek/mtk_hdmi.c
> > index 5838c44cbf6f..3196189429bc 100644
> > --- a/drivers/gpu/drm/mediatek/mtk_hdmi.c
> > +++ b/drivers/gpu/drm/mediatek/mtk_hdmi.c
> > @@ -1224,12 +1224,14 @@ static int mtk_hdmi_bridge_mode_valid(struct drm_bridge *bridge,
> > return MODE_BAD;
> > }
> >
> > - if (hdmi->conf->cea_modes_only && !drm_match_cea_mode(mode))
> > - return MODE_BAD;
> > + if (hdmi->conf) {
> > + if (hdmi->conf->cea_modes_only && !drm_match_cea_mode(mode))
> > + return MODE_BAD;
> >
> > - if (hdmi->conf->max_mode_clock &&
> > - mode->clock > hdmi->conf->max_mode_clock)
> > - return MODE_CLOCK_HIGH;
> > + if (hdmi->conf->max_mode_clock &&
> > + mode->clock > hdmi->conf->max_mode_clock)
> > + return MODE_CLOCK_HIGH;
> > + }
> >
> > if (mode->clock < 27000)
> > return MODE_CLOCK_LOW;
> >
>
> Hello, friendly ping!
>
> Can I please get a review (or merge) of this commit?
>
> This is an important fix for a null pointer KP and restores HDMI functionality.
Applied to mediatek-drm-fixes [1], thanks.
[1] https://git.kernel.org/pub/scm/linux/kernel/git/chunkuang.hu/linux.git/log/?h=mediatek-drm-fixes
Regards,
Chun-Kuang.
>
> Thanks,
> - Angelo
