[PATCH 12/14] drm/i915/dsb: Clear DSB_ENABLE_DEWAKE once the DSB is done

[Ville Syrjala]

From: Ville Syrjälä <ville.syrjala at linux.intel.com>

In order to avoid the DSB keeping the DEwake permanently
asserted we must clear DSB_PMCTRL_2.DSB_FORCE_DEWAKE once
we are done. For good measure do the same for
DSB_PMCTRL.DSB_ENABLE_DEWAKE.

Experimentally this doens't seem to be actually necessary
(unlike with DSB_FORCE_DEWAKE). That is, the DSB_ENABLE_DEWAKE
doesn't seem to do anything whenever the DSB is not active.
But I'd hate to waste a ton of power in case there I'm wrong
and there is some way DEwake could remaing asserted. One extra
register write is a small price to pay for some peace of mind.

Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 drivers/gpu/drm/i915/display/intel_dsb.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dsb.c b/drivers/gpu/drm/i915/display/intel_dsb.c
index cf710f0bf430..fad37e7856b1 100644
--- a/drivers/gpu/drm/i915/display/intel_dsb.c
+++ b/drivers/gpu/drm/i915/display/intel_dsb.c
@@ -464,8 +464,10 @@ void intel_dsb_finish(struct intel_dsb *dsb)
 	/*
 	 * DSB_FORCE_DEWAKE remains active even after DSB is
 	 * disabled, so make sure to clear it (if set during
-	 * intel_dsb_commit()).
+	 * intel_dsb_commit()). And clear DSB_ENABLE_DEWAKE as
+	 * well for good measure.
 	 */
+	intel_dsb_reg_write(dsb, DSB_PMCTRL(crtc->pipe, dsb->id), 0);
 	intel_dsb_reg_write_masked(dsb, DSB_PMCTRL_2(crtc->pipe, dsb->id),
 				   DSB_FORCE_DEWAKE, 0);
 
-- 
2.44.2