[Intel-gfx] [PATCH] CHROMIUM: drivers: i915: select non-alternate SSC frequency for some systems

[james.ausmus at intel.com]

From: Simon Que <sque at chromium.org>

When initializing VBT default values, the alternate BIOS SSC frequency
is selected.  This patch allows the non-alternate frequency to be
selected as a default, for specified systems.  There is a DMI match list
for systems that are to use the non-alternate frequency.  Currently,
only Lumpy is on the list.

BUG=chrome-os-partner:5525
TEST=Run on Lumpy with dev switch off.  The display should be working,
even if the backlight is not -- something should be visible.

Change-Id: I6c5c57ab38cfb21731a6d56b143c7906b8c85360
Signed-off-by: Simon Que <sque at chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/11339
Reviewed-by: Bryan Freed <bfreed at chromium.org>
[marcheu: fixups for 3.8]
Signed-off-by: Stéphane Marchesin <marcheu at chromium.org>
---
 drivers/gpu/drm/i915/intel_bios.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c
index 55ffba1..b6a8b69 100644
--- a/drivers/gpu/drm/i915/intel_bios.c
+++ b/drivers/gpu/drm/i915/intel_bios.c
@@ -631,6 +631,17 @@ parse_device_mapping(struct drm_i915_private *dev_priv,
 	return;
 }
 
+static const struct dmi_system_id lvds_do_not_use_alternate_frequency[] = {
+	{
+		.callback = NULL,
+		.ident = "Lumpy",
+		.matches = {
+			DMI_MATCH(DMI_PRODUCT_NAME, "Lumpy"),
+		}
+	},
+	{ }
+};
+
 static void
 init_vbt_defaults(struct drm_i915_private *dev_priv)
 {
@@ -651,7 +662,10 @@ init_vbt_defaults(struct drm_i915_private *dev_priv)
 
 	/* Default to using SSC */
 	dev_priv->lvds_use_ssc = 1;
-	dev_priv->lvds_ssc_freq = intel_bios_ssc_frequency(dev, 1);
+	if (dmi_check_system(lvds_do_not_use_alternate_frequency))
+		dev_priv->lvds_ssc_freq = intel_bios_ssc_frequency(dev, 0);
+	else
+		dev_priv->lvds_ssc_freq = intel_bios_ssc_frequency(dev, 1);
 	DRM_DEBUG_KMS("Set default to SSC at %dMHz\n", dev_priv->lvds_ssc_freq);
 }
 
-- 
1.8.3.2