drm/i915: Disable FIFO underrun reporting around IBX transcoder B workaround
Doing the IBX transcoder B workaround causes underruns on
pipe/transcoder A. Just hide them by disabling underrun reporting for
pipe A around the workaround.
It might be possible to avoid the underruns by moving the workaround
to be applied only when enabling pipe A. But I was too lazy to try it
right now, and the current method has been proven to work, so didn't
want to change it too hastily.
Note that this can re-enable underrun reporting on pipe A if was
already disabled due to a previous actual underrun. But that's OK, we
may just get a second underrun report if another real underron occurrs
on pipe A.
v2: Note that pipe A underruns can get re-enabled due to this (Jani)
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org> (v1)
Link: http://patchwork.freedesktop.org/patch/msgid/1446225802-11180-1-git-send-email-ville.syrjala@linux.intel.com
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 5264887..278f025 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -3655,6 +3655,13 @@
* matching HDMI port to be enabled on transcoder A.
*/
if (HAS_PCH_IBX(dev) && crtc->pipe == PIPE_B && port != PORT_A) {
+ /*
+ * We get CPU/PCH FIFO underruns on the other pipe when
+ * doing the workaround. Sweep them under the rug.
+ */
+ intel_set_cpu_fifo_underrun_reporting(dev_priv, PIPE_A, false);
+ intel_set_pch_fifo_underrun_reporting(dev_priv, PIPE_A, false);
+
/* always enable with pattern 1 (as per spec) */
DP &= ~(DP_PIPEB_SELECT | DP_LINK_TRAIN_MASK);
DP |= DP_PORT_EN | DP_LINK_TRAIN_PAT_1;
@@ -3664,6 +3671,10 @@
DP &= ~DP_PORT_EN;
I915_WRITE(intel_dp->output_reg, DP);
POSTING_READ(intel_dp->output_reg);
+
+ intel_wait_for_vblank_if_active(dev_priv->dev, PIPE_A);
+ intel_set_cpu_fifo_underrun_reporting(dev_priv, PIPE_A, true);
+ intel_set_pch_fifo_underrun_reporting(dev_priv, PIPE_A, true);
}
msleep(intel_dp->panel_power_down_delay);