Commit 3b8e19a0 authored Oct 28, 2021 by AngeloGioacchino Del Regno Committed by Chun-Kuang Hu Dec 13, 2021

drm/mediatek: hdmi: Perform NULL pointer check for mtk_hdmi_conf



In commit 41ca9caa
("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 c91026a9
("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: 41ca9caa ("drm/mediatek: hdmi: Add check for CEA modes only")
Fixes: c91026a9 ("drm/mediatek: hdmi: Add optional limit on maximal HDMI mode clock")
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>

parent fa55b7dc

drivers/gpu/drm/mediatek/mtk_hdmi.c

+7 −5

Original line number	Diff line number	Diff line
		@@ -1224,12 +1224,14 @@ static int mtk_hdmi_bridge_mode_valid(struct drm_bridge *bridge,
		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 (mode->clock < 27000)
		return MODE_CLOCK_LOW;