linux-kernel - [PATCH v3 4/5] gpu/drm: mediatek: hdmi: add optional limit on maximal HDMI mode clock

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Date:   Mon, 19 Apr 2021 09:32:43 +0200
From:   Neil Armstrong <narmstrong@...libre.com>
To:     chunkuang.hu@...nel.org, p.zabel@...gutronix.de,
        matthias.bgg@...il.com
Cc:     dri-devel@...ts.freedesktop.org,
        linux-mediatek@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Neil Armstrong <narmstrong@...libre.com>,
        Fabien Parent <fparent@...libre.com>
Subject: [PATCH v3 4/5] gpu/drm: mediatek: hdmi: add optional limit on maximal HDMI mode clock

Some SoCs like the MT8167 have a hard limit on the maximal supported HDMI TMDS
clock, so add a configuration value to filter out those modes.

Signed-off-by: Fabien Parent <fparent@...libre.com>
Signed-off-by: Neil Armstrong <narmstrong@...libre.com>
---
 drivers/gpu/drm/mediatek/mtk_hdmi.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/gpu/drm/mediatek/mtk_hdmi.c b/drivers/gpu/drm/mediatek/mtk_hdmi.c
index 0539262e69d3..bc50d97f2553 100644
--- a/drivers/gpu/drm/mediatek/mtk_hdmi.c
+++ b/drivers/gpu/drm/mediatek/mtk_hdmi.c
@@ -149,6 +149,7 @@ struct hdmi_audio_param {
 struct mtk_hdmi_conf {
 	bool tz_disabled;
 	bool cea_modes_only;
+	unsigned long max_mode_clock;
 };
 
 struct mtk_hdmi {
@@ -1226,6 +1227,10 @@ static int mtk_hdmi_bridge_mode_valid(struct drm_bridge *bridge,
 	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;
 	if (mode->clock > 297000)
-- 
2.25.1