[Intel-gfx] [PATCH 3/3] drm/i915: Replace ILK eDP underrun suppression with something better
ville.syrjala at linux.intel.com
ville.syrjala at linux.intel.com
Fri Apr 1 18:53:19 UTC 2016
From: Ville Syrjälä <ville.syrjala at linux.intel.com>
The underruns we were seeing when enabling eDP port A on ILK seem to
have been caused by prematurely clearing the LP1+ watermark values when
disabling LP1+ watermarks. Now that the watermarks are handled
properly, we can rip out the underrun suppression around the port A
enable.
We still need to worry about the underruns on FDI when enabling
the eDP PLL. But as Bspec tells us, we can avoid that by a vblank
wait on the pipe driving FDI just prior to enabling the eDP PLL.
Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
drivers/gpu/drm/i915/intel_dp.c | 36 +++++++++---------------------------
1 file changed, 9 insertions(+), 27 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 95fe01d55bce..7523558190d1 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -2215,6 +2215,15 @@ static void ironlake_edp_pll_on(struct intel_dp *intel_dp)
POSTING_READ(DP_A);
udelay(500);
+ /*
+ * [DevILK] Work around required when enabling DP PLL
+ * while a pipe is enabled going to FDI:
+ * 1. Wait for the start of vertical blank on the enabled pipe going to FDI
+ * 2. Program DP PLL enable
+ */
+ if (IS_GEN5(dev_priv))
+ intel_wait_for_vblank_if_active(dev_priv->dev, !crtc->pipe);
+
intel_dp->DP |= DP_PLL_ENABLE;
I915_WRITE(DP_A, intel_dp->DP);
@@ -2630,7 +2639,6 @@ static void intel_enable_dp(struct intel_encoder *encoder)
struct drm_i915_private *dev_priv = dev->dev_private;
struct intel_crtc *crtc = to_intel_crtc(encoder->base.crtc);
uint32_t dp_reg = I915_READ(intel_dp->output_reg);
- enum port port = dp_to_dig_port(intel_dp)->port;
enum pipe pipe = crtc->pipe;
if (WARN_ON(dp_reg & DP_PORT_EN))
@@ -2643,17 +2651,6 @@ static void intel_enable_dp(struct intel_encoder *encoder)
intel_dp_enable_port(intel_dp);
- if (port == PORT_A && IS_GEN5(dev_priv)) {
- /*
- * Underrun reporting for the other pipe was disabled in
- * g4x_pre_enable_dp(). The eDP PLL and port have now been
- * enabled, so it's now safe to re-enable underrun reporting.
- */
- intel_wait_for_vblank_if_active(dev_priv->dev, !pipe);
- intel_set_cpu_fifo_underrun_reporting(dev_priv, !pipe, true);
- intel_set_pch_fifo_underrun_reporting(dev_priv, !pipe, true);
- }
-
edp_panel_vdd_on(intel_dp);
edp_panel_on(intel_dp);
edp_panel_vdd_off(intel_dp, true);
@@ -2699,26 +2696,11 @@ static void vlv_enable_dp(struct intel_encoder *encoder)
static void g4x_pre_enable_dp(struct intel_encoder *encoder)
{
- struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
struct intel_dp *intel_dp = enc_to_intel_dp(&encoder->base);
enum port port = dp_to_dig_port(intel_dp)->port;
- enum pipe pipe = to_intel_crtc(encoder->base.crtc)->pipe;
intel_dp_prepare(encoder);
- if (port == PORT_A && IS_GEN5(dev_priv)) {
- /*
- * We get FIFO underruns on the other pipe when
- * enabling the CPU eDP PLL, and when enabling CPU
- * eDP port. We could potentially avoid the PLL
- * underrun with a vblank wait just prior to enabling
- * the PLL, but that doesn't appear to help the port
- * enable case. Just sweep it all under the rug.
- */
- intel_set_cpu_fifo_underrun_reporting(dev_priv, !pipe, false);
- intel_set_pch_fifo_underrun_reporting(dev_priv, !pipe, false);
- }
-
/* Only ilk+ has port A */
if (port == PORT_A)
ironlake_edp_pll_on(intel_dp);
--
2.7.4
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