From f69e515699d8e9b1c25dcfe1c4c6f435087495d2 Mon Sep 17 00:00:00 2001 From: Duncan Laurie Date: Wed, 13 Nov 2013 17:59:43 -0800 Subject: [PATCH] i915: Use 120MHz LVDS SSC clock for gen5/gen6/gen7 We had been using a DMI table workaround to select the right frequency for devices, but this is fragile and must be updated with every new platform. Instead the default case when VBT is missing is changed to use 120MHz clock for LVDS SSC for these generations. The docs for 2010-Core, SandyBridge, and IvyBridge all indicate that the reference frequency for LVDS is 120MHz: "2010 Core" http://intellinuxgraphics.org/IHD_OS_Vol3_Part3r2.pdf page 38 Reference Frequency: 120MHz for CRT and LVDS. 100MHz for the FDI. "2011 SandyBridge" http://intellinuxgraphics.org/documentation/SNB/IHD_OS_Vol3_Part3.pdf page 33 Reference Frequency: 120MHz for CRT, HDMI, LVDS. 100MHz for the FDI. "2012 IvyBridge" http://intellinuxgraphics.org/documentation/IVB/IHD_OS_Vol3_Part4.pdf page 27 Reference Frequency: 120 MHz for CRT, HDMI, LVDS, 100MHz for the FDI. Signed-off-by: Duncan Laurie [olof: Fixup for recent base, switched from if/else to single call] Signed-off-by: Olof Johansson Reviewed-by: Rodrigo Vivi Signed-off-by: Daniel Vetter --- drivers/gpu/drm/i915/intel_bios.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c index 6dd622d..e4fba39 100644 --- a/drivers/gpu/drm/i915/intel_bios.c +++ b/drivers/gpu/drm/i915/intel_bios.c @@ -790,7 +790,12 @@ init_vbt_defaults(struct drm_i915_private *dev_priv) /* Default to using SSC */ dev_priv->vbt.lvds_use_ssc = 1; - dev_priv->vbt.lvds_ssc_freq = intel_bios_ssc_frequency(dev, 1); + /* + * Core/SandyBridge/IvyBridge use alternative (120MHz) reference + * clock for LVDS. + */ + dev_priv->vbt.lvds_ssc_freq = intel_bios_ssc_frequency(dev, + !HAS_PCH_SPLIT(dev)); DRM_DEBUG_KMS("Set default to SSC at %dMHz\n", dev_priv->vbt.lvds_ssc_freq); for (port = PORT_A; port < I915_MAX_PORTS; port++) { -- 2.7.4