[PATCH] drm/i915: Add quirk to disable SSC on Lenovo U160 LVDS

[Keith Packard]

We've tried several times to make this machine 'just work', but every
patch that does causes many other machines to fail. This adds a quirk
which special cases this hardware and forces ssc to be
disabled. There's no way to override this from the command line; that
would be a significantly more invasive change.

Signed-off-by: Keith Packard <keithp@xxxxxxxxxx>
Tested-by: Robse <rob-se@xxxxxxx>

---
 drivers/gpu/drm/i915/i915_drv.h      |    1 +
 drivers/gpu/drm/i915/intel_display.c |   15 ++++++++++++++-
 2 files changed, 15 insertions(+), 1 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index f245c58..6042921 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -262,6 +262,7 @@ enum intel_pch {
 };
 
 #define QUIRK_PIPEA_FORCE (1<<0)
+#define QUIRK_LVDS_SSC_DISABLE (1<<1)
 
 struct intel_fbdev;
 
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 21b6f93..252c6f0 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -4305,7 +4305,8 @@ static void intel_update_watermarks(struct drm_device *dev)
 
 static inline bool intel_panel_use_ssc(struct drm_i915_private *dev_priv)
 {
-	return dev_priv->lvds_use_ssc && i915_panel_use_ssc;
+	return dev_priv->lvds_use_ssc && i915_panel_use_ssc
+		&& !(dev_priv->quirks & QUIRK_LVDS_SSC_DISABLE);
 }
 
 static int i9xx_crtc_mode_set(struct drm_crtc *crtc,
@@ -7810,6 +7811,15 @@ static void quirk_pipea_force (struct drm_device *dev)
 	DRM_DEBUG_DRIVER("applying pipe a force quirk\n");
 }
 
+/*
+ * Some machines (Lenovo U160) do not work with SSC on LVDS for some reason
+ */
+static void quirk_ssc_force_disable (struct drm_device *dev)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	dev_priv->quirks |= QUIRK_LVDS_SSC_DISABLE;
+}
+
 struct intel_quirk {
 	int device;
 	int subsystem_vendor;
@@ -7838,6 +7848,9 @@ struct intel_quirk intel_quirks[] = {
 	/* 855 & before need to leave pipe A & dpll A up */
 	{ 0x3582, PCI_ANY_ID, PCI_ANY_ID, quirk_pipea_force },
 	{ 0x2562, PCI_ANY_ID, PCI_ANY_ID, quirk_pipea_force },
+
+	/* Lenovo U160 cannot use SSC on LVDS */
+	{ 0x0046, 0x17aa, 0x3920, quirk_ssc_force_disable },
 };
 
 static void intel_init_quirks(struct drm_device *dev)
-- 
1.7.5.4



-- 
keith.packard@xxxxxxxxx

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