[PATCH v5 2/4] drm/i915: LVDS pixel clock check

Mika Kahola
2015-08-18T11:37:24Z

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 LVDS.

V2:
- removed computation for max pixel clock

V3:
- cleanup by removing unnecessary lines

V4:
- moved supported dotclock check from mode_valid() to intel_lvds_init()

V5:
- dotclock check moved back to mode_valid() function
- dotclock check for fixed mode

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

diff --git a/drivers/gpu/drm/i915/intel_lvds.c b/drivers/gpu/drm/i915/intel_lvds.c
index 881b5d1..0794dc8 100644
--- a/drivers/gpu/drm/i915/intel_lvds.c
+++ b/drivers/gpu/drm/i915/intel_lvds.c
@@ -289,11 +289,14 @@ intel_lvds_mode_valid(struct drm_connector *connector,
{
struct intel_connector *intel_connector = to_intel_connector(connector);
struct drm_display_mode *fixed_mode = intel_connector->panel.fixed_mode;
+ int max_pixclk = to_i915(connector->dev)->max_dotclk_freq;

if (mode->hdisplay > fixed_mode->hdisplay)
return MODE_PANEL;
if (mode->vdisplay > fixed_mode->vdisplay)
return MODE_PANEL;
+ if (fixed_mode->clock > max_pixclk)
+ return MODE_CLOCK_HIGH;

return MODE_OK;
}
--
1.9.1