drm/i915: Use CK505 as non-SSC source where available
When trying to use SSC on Ibex Peak without CK505, any non-SSC outputs
(like VGA or TV) get broken. So, do not use SSC on Ibex Peak unless
there is a CK505 available (as specified by the VBT).
On Cougar Point, all clocking is internal, so SSC can always be used,
and there will never be a CK505 available.
This eliminates VGA shimmer on some Ironlake machines which have a
CK505 clock source.
References: https://bugzilla.kernel.org/show_bug.cgi?id=21742
References: https://bugs.freedesktop.org/show_bug.cgi?id=38750
Signed-off-by: Keith Packard <keithp@keithp.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index f999935..4c9684c 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -5119,6 +5119,8 @@
bool has_cpu_edp = false;
bool has_pch_edp = false;
bool has_panel = false;
+ bool has_ck505 = false;
+ bool can_ssc = false;
/* We need to take the global config into account */
list_for_each_entry(encoder, &mode_config->encoder_list,
@@ -5137,8 +5139,18 @@
break;
}
}
- DRM_DEBUG_KMS("has_panel %d has_lvds %d has_pch_edp %d has_cpu_edp %d\n",
- has_panel, has_lvds, has_pch_edp, has_cpu_edp);
+
+ if (HAS_PCH_IBX(dev)) {
+ has_ck505 = dev_priv->display_clock_mode;
+ can_ssc = has_ck505;
+ } else {
+ has_ck505 = false;
+ can_ssc = true;
+ }
+
+ DRM_DEBUG_KMS("has_panel %d has_lvds %d has_pch_edp %d has_cpu_edp %d has_ck505 %d\n",
+ has_panel, has_lvds, has_pch_edp, has_cpu_edp,
+ has_ck505);
/* Ironlake: try to setup display ref clock before DPLL
* enabling. This is only under driver's control after
@@ -5148,14 +5160,18 @@
temp = I915_READ(PCH_DREF_CONTROL);
/* Always enable nonspread source */
temp &= ~DREF_NONSPREAD_SOURCE_MASK;
- temp |= DREF_NONSPREAD_SOURCE_ENABLE;
+
+ if (has_ck505)
+ temp |= DREF_NONSPREAD_CK505_ENABLE;
+ else
+ temp |= DREF_NONSPREAD_SOURCE_ENABLE;
if (has_panel) {
temp &= ~DREF_SSC_SOURCE_MASK;
temp |= DREF_SSC_SOURCE_ENABLE;
/* SSC must be turned on before enabling the CPU output */
- if (intel_panel_use_ssc(dev_priv)) {
+ if (intel_panel_use_ssc(dev_priv) && can_ssc) {
DRM_DEBUG_KMS("Using SSC on panel\n");
temp |= DREF_SSC1_ENABLE;
}
@@ -5169,7 +5185,7 @@
/* Enable CPU source on CPU attached eDP */
if (has_cpu_edp) {
- if (intel_panel_use_ssc(dev_priv)) {
+ if (intel_panel_use_ssc(dev_priv) && can_ssc) {
DRM_DEBUG_KMS("Using SSC on eDP\n");
temp |= DREF_CPU_SOURCE_OUTPUT_DOWNSPREAD;
}