drm/i915: DisplayPort-MST pixel clock check
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.
V2:
- removed computation for max pixel clock
V3:
- cleanup by removing unnecessary lines
V4:
- max_pixclk variable renamed as max_dotclk
Signed-off-by: Mika Kahola <mika.kahola@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1454419003-6001-4-git-send-email-mika.kahola@intel.com
diff --git a/drivers/gpu/drm/i915/intel_dp_mst.c b/drivers/gpu/drm/i915/intel_dp_mst.c
index 2a2ab30..a2bd698 100644
--- a/drivers/gpu/drm/i915/intel_dp_mst.c
+++ b/drivers/gpu/drm/i915/intel_dp_mst.c
@@ -371,6 +371,8 @@
intel_dp_mst_mode_valid(struct drm_connector *connector,
struct drm_display_mode *mode)
{
+ int max_dotclk = to_i915(connector->dev)->max_dotclk_freq;
+
/* TODO - validate mode against available PBN for link */
if (mode->clock < 10000)
return MODE_CLOCK_LOW;
@@ -378,6 +380,9 @@
if (mode->flags & DRM_MODE_FLAG_DBLCLK)
return MODE_H_ILLEGAL;
+ if (mode->clock > max_dotclk)
+ return MODE_CLOCK_HIGH;
+
return MODE_OK;
}