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SubjectRe: [PATCH] drm/mediatek: hdmi: Perform NULL pointer check for mtk_hdmi_conf
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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@collabora.com>
> ---
> 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.

Thanks,
- Angelo

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