[PATCH 3/3] drm/i915: Check HDMI TMDS clock rate from DPCD

[Mika Kahola <mika.kahola@xxxxxxxxx>]

Read TMDS clock rate from DPCD for HDMI to filter out
modes that might require higher TMDS clock rate than
supported.

Signed-off-by: Mika Kahola <mika.kahola@xxxxxxxxx>
---
 drivers/gpu/drm/i915/intel_dp.c   | 3 +++
 drivers/gpu/drm/i915/intel_drv.h  | 1 +
 drivers/gpu/drm/i915/intel_hdmi.c | 7 ++++---
 3 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 74a04ce..0fd078c 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -4591,6 +4591,9 @@ static void intel_dp_get_dfp(struct intel_dp *intel_dp)
 		if (intel_dp->dfp.type & DP_DS_PORT_TYPE_VGA) {
 			intel_dp->dfp.dot_clk = dfp_info[1] * 8 * 1000;
 			DRM_DEBUG_KMS("max pixel rate for VGA is %d kHz\n", intel_dp->dfp.dot_clk);
+		} else if (!(intel_dp->dfp.type & DP_DS_PORT_TYPE_WIRELESS)) {
+			intel_dp->dfp.tmds_clk = DIV_ROUND_CLOSEST(dfp_info[1] * 25 * 1000, 10);
+			DRM_DEBUG_KMS("max TMDS clock is %d kHz\n", intel_dp->dfp.tmds_clk);
 		}
 	}
 }
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 9798a59..8bf97da 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -799,6 +799,7 @@ struct intel_dp_dfp {
 	int type;
 	bool detailed_cap_info;
 	int dot_clk; /* pixel rate for VGA dongles */
+	int tmds_clk;
 };
 
 struct intel_dp {
diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
index e1012d6..70e8e17 100644
--- a/drivers/gpu/drm/i915/intel_hdmi.c
+++ b/drivers/gpu/drm/i915/intel_hdmi.c
@@ -1170,13 +1170,14 @@ static void pch_post_disable_hdmi(struct intel_encoder *encoder)
 static int hdmi_port_clock_limit(struct intel_hdmi *hdmi, bool respect_dvi_limit)
 {
 	struct drm_device *dev = intel_hdmi_to_dev(hdmi);
+	int tmds_clock = hdmi_to_dig_port(hdmi)->dp.dfp.tmds_clk;
 
 	if ((respect_dvi_limit && !hdmi->has_hdmi_sink) || IS_G4X(dev))
-		return 165000;
+		return (tmds_clock > 0 ? min(165000, tmds_clock) : 165000);
 	else if (IS_HASWELL(dev) || INTEL_INFO(dev)->gen >= 8)
-		return 300000;
+		return (tmds_clock > 0 ? min(300000, tmds_clock) : 300000);
 	else
-		return 225000;
+		return (tmds_clock > 0 ? min(225000, tmds_clock) : 225000);
 }
 
 static enum drm_mode_status
-- 
1.9.1

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