From f8700b34bd8f0433e6f7a5538c474a3dfcb4cc44 Mon Sep 17 00:00:00 2001
From: Mika Kahola <mika.kahola@intel.com>
Date: Tue, 2 Feb 2016 15:16:42 +0200
Subject: [PATCH] drm/i915: CRT pixel clock check
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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 CRT.
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/1454419003-6001-6-git-send-email-mika.kahola@intel.com
---
drivers/gpu/drm/i915/intel_crt.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/gpu/drm/i915/intel_crt.c b/drivers/gpu/drm/i915/intel_crt.c
index 9c89df1af036d..ad5dfabc452ec 100644
--- a/drivers/gpu/drm/i915/intel_crt.c
+++ b/drivers/gpu/drm/i915/intel_crt.c
@@ -216,6 +216,7 @@ intel_crt_mode_valid(struct drm_connector *connector,
struct drm_display_mode *mode)
{
struct drm_device *dev = connector->dev;
+ int max_dotclk = to_i915(dev)->max_dotclk_freq;
int max_clock = 0;
if (mode->flags & DRM_MODE_FLAG_DBLSCAN)
@@ -231,6 +232,9 @@ intel_crt_mode_valid(struct drm_connector *connector,
if (mode->clock > max_clock)
return MODE_CLOCK_HIGH;
+ if (mode->clock > max_dotclk)
+ return MODE_CLOCK_HIGH;
+
/* The FDI receiver on LPT only supports 8bpc and only has 2 lanes. */
if (HAS_PCH_LPT(dev) &&
(ironlake_get_lanes_required(mode->clock, 270000, 24) > 2))