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drm/i915: Replace ILK eDP underrun suppression with something better 

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@ffwll.ch>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1459536799-18109-4-git-send-email-ville.syrjala@linux.intel.com
Reviewed-by: Patrik Jakobsson <patrik.jakobsson@linux.intel.com>
This commit is contained in:
Ville Syrjälä 2016-04-01 21:53:19 +03:00
parent 1204d5baa8
commit 6b23f3e8a6
1 changed files with 9 additions and 27 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

36
drivers/gpu/drm/i915/intel_dp.c
View File

@ -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);