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From:   Neil Armstrong <narmstrong@baylibre.com>
To:     daniel@ffwll.ch
Cc:     dri-devel@lists.freedesktop.org, linux-amlogic@lists.infradead.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        Neil Armstrong <narmstrong@baylibre.com>,
        Maxime Jourdan <mjourdan@baylibre.com>
Subject: [PATCH] drm/meson: fix TMDS clock filtering for DMT monitors
Date:   Wed, 20 Mar 2019 09:11:10 +0100
Message-Id: <20190320081110.1718-1-narmstrong@baylibre.com>
MIME-Version: 1.0
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Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

DMT monitors does not necessarely report a maximum TMDS clock
in a VSDB EDID extension.

In this case, all modes are wrongly rejected, including
the DRM fallback EDID.

This patch only rejects modes whith clock > max_tmds_clock if
the max_tmds_clock is specified. This will only reject
4:2:0 HDMI2.0 modes, who reports a clock > max_tmds_clock.

Reported-by: Maxime Jourdan <mjourdan@baylibre.com>
Fixes: d7d8fb7046b6 ("drm/meson: add HDMI div40 TMDS mode")
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
---
 drivers/gpu/drm/meson/meson_dw_hdmi.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/meson/meson_dw_hdmi.c b/drivers/gpu/drm/meson/meson_dw_hdmi.c
index e28814f4ea6c..563953ec6ad0 100644
--- a/drivers/gpu/drm/meson/meson_dw_hdmi.c
+++ b/drivers/gpu/drm/meson/meson_dw_hdmi.c
@@ -569,7 +569,8 @@ dw_hdmi_mode_valid(struct drm_connector *connector,
 	DRM_DEBUG_DRIVER("Modeline " DRM_MODE_FMT "\n", DRM_MODE_ARG(mode));
 
 	/* If sink max TMDS clock, we reject the mode */
-	if (mode->clock > connector->display_info.max_tmds_clock)
+	if (connector->display_info.max_tmds_clock &&
+	    mode->clock > connector->display_info.max_tmds_clock)
 		return MODE_BAD;
 
 	/* Check against non-VIC supported modes */
-- 
2.21.0