[Intel-gfx] [PATCH v4 1/6] drm/i915: DisplayPort pixel clock check

[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.

V2:
- removed computation for max DOT clock

V3:
- cleanup by removing unnecessary lines

V4:
- max_pixclk renamed as max_dotclk

Signed-off-by: Mika Kahola <mika.kahola at intel.com>
---
 drivers/gpu/drm/i915/intel_dp.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index f44aba1..396d1a1 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -203,6 +203,7 @@ intel_dp_mode_valid(struct drm_connector *connector,
 	struct drm_display_mode *fixed_mode = intel_connector->panel.fixed_mode;
 	int target_clock = mode->clock;
 	int max_rate, mode_rate, max_lanes, max_link_clock;
+	int max_dotclk = to_i915(connector->dev)->max_dotclk_freq;
 
 	if (is_edp(intel_dp) && fixed_mode) {
 		if (mode->hdisplay > fixed_mode->hdisplay)
@@ -220,7 +221,7 @@ intel_dp_mode_valid(struct drm_connector *connector,
 	max_rate = intel_dp_max_data_rate(max_link_clock, max_lanes);
 	mode_rate = intel_dp_link_required(target_clock, 18);
 
-	if (mode_rate > max_rate)
+	if (mode_rate > max_rate || target_clock > max_dotclk)
 		return MODE_CLOCK_HIGH;
 
 	if (mode->clock < 10000)
-- 
1.9.1