drm/i915: Hack to tie both common lanes together on chv

It looks like frobbing the cmnreset line on pne PHY disturbs the other
PHY on chv. The result is a black screen. On HDMI it's just a flash of
black, but DP usually falls over and can't get back up.

As a workaround set up the power domains so that both common lane
wells power up and down together. I also tried leaving the cmnreset
deasserted even the if the power well goes down but that didn't seem
acceptable to the PHY.

Reviewed-by: Rafael Barbalho <rafael.barbalho@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 12 insertions, 2 deletions

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index da43e30ad60b..aaae22815965 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -6877,13 +6877,23 @@ static struct i915_power_well chv_power_wells[] = {
 #endif
         {
                 .name = "dpio-common-bc",
-                .domains = CHV_DPIO_CMN_BC_POWER_DOMAINS,
+                /*
+                 * XXX: cmnreset for one PHY seems to disturb the other.
+                 * As a workaround keep both powered on at the same
+                 * time for now.
+                 */
+                .domains = CHV_DPIO_CMN_BC_POWER_DOMAINS | CHV_DPIO_CMN_D_POWER_DOMAINS,
                 .data = PUNIT_POWER_WELL_DPIO_CMN_BC,
                 .ops = &chv_dpio_cmn_power_well_ops,
         },
         {
                 .name = "dpio-common-d",
-                .domains = CHV_DPIO_CMN_D_POWER_DOMAINS,
+                /*
+                 * XXX: cmnreset for one PHY seems to disturb the other.
+                 * As a workaround keep both powered on at the same
+                 * time for now.
+                 */
+                .domains = CHV_DPIO_CMN_BC_POWER_DOMAINS | CHV_DPIO_CMN_D_POWER_DOMAINS,
                 .data = PUNIT_POWER_WELL_DPIO_CMN_D,
                 .ops = &chv_dpio_cmn_power_well_ops,
         },