[Intel-gfx] [PATCH 9/9] drm/i915: Check pixel clock when setting mode for DP-MST

[Mika Kahola]

It is possible the we request to have a mode that has
higher pixel clock than our HW can support. This patch
checks if requested pixel clock is lower than the one
supported by the HW. The requested mode is discarded
if we cannot support the requested pixel clock.

This patch applies to DisplayPort MST.

Signed-off-by: Mika Kahola <mika.kahola at intel.com>
---
 drivers/gpu/drm/i915/intel_dp_mst.c | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_dp_mst.c b/drivers/gpu/drm/i915/intel_dp_mst.c
index 6e4cc53..0fb9a3d 100644
--- a/drivers/gpu/drm/i915/intel_dp_mst.c
+++ b/drivers/gpu/drm/i915/intel_dp_mst.c
@@ -343,10 +343,38 @@ static int intel_dp_mst_get_modes(struct drm_connector *connector)
 	return intel_dp_mst_get_ddc_modes(connector);
 }
 
+static int
+intel_dp_mst_max_pixclk(struct intel_dp *intel_dp)
+{
+	struct intel_digital_port *intel_dig_port = dp_to_dig_port(intel_dp);
+	struct intel_encoder *encoder = &intel_dig_port->base;
+	struct drm_device *dev = encoder->base.dev;
+	struct drm_crtc *crtc = intel_dig_port->base.base.crtc;
+	struct drm_i915_private *dev_priv = to_i915(dev);
+	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
+
+	if (IS_CHERRYVIEW(dev))
+		return  DIV_ROUND_UP(dev_priv->max_cdclk_freq * 100, 95);
+	else if (IS_VALLEYVIEW(dev))
+		return  DIV_ROUND_UP(dev_priv->max_cdclk_freq * 100, 90);
+	else if (IS_BROADWELL(dev) && intel_crtc->config->ips_enabled)
+		return  DIV_ROUND_UP(dev_priv->max_cdclk_freq * 100, 95);
+	else
+		return dev_priv->max_cdclk_freq;
+}
+
 static enum drm_mode_status
 intel_dp_mst_mode_valid(struct drm_connector *connector,
 			struct drm_display_mode *mode)
 {
+
+	struct intel_connector *intel_connector = to_intel_connector(connector);
+	struct intel_dp *intel_dp = intel_connector->mst_port;
+	int max_pixclk = intel_dp_mst_max_pixclk(intel_dp);
+
+	if (mode->clock > max_pixclk)
+		return MODE_CLOCK_HIGH;
+
 	/* TODO - validate mode against available PBN for link */
 	if (mode->clock < 10000)
 		return MODE_CLOCK_LOW;
-- 
1.9.1