[Intel-gfx] [PATCH 1/4] drm/i915/psr: Prevent PSR exit when a non-pipe related register is written

[José Roberto de Souza]

Any write in any display register was causing HW to exit PSR,
masking it to allow more power savings. Writes to pipe related
registers will still cause HW to exit PSR.
This is already masked for PSR2.

It also do not break the Display WA #0884, writes to CURSURFLIVE
are still causing hardware to exit PSR. This was tested in CNL machine
by triggering a write to CURSURFLIVE when a debugfs was read by user.

Bspec: 7721 and 8042

v4: Checked that it do not breaks WA #0884 and added this information
to the commit message.

Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
Reviewed-by: Dhinakaran Pandiyan <dhinakaran.pandiyan at intel.com>
Signed-off-by: José Roberto de Souza <jose.souza at intel.com>
---
 drivers/gpu/drm/i915/intel_psr.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_psr.c b/drivers/gpu/drm/i915/intel_psr.c
index 0d548292dd09..e35a3b94fa69 100644
--- a/drivers/gpu/drm/i915/intel_psr.c
+++ b/drivers/gpu/drm/i915/intel_psr.c
@@ -667,7 +667,8 @@ static void hsw_psr_enable_source(struct intel_dp *intel_dp,
 		I915_WRITE(EDP_PSR_DEBUG,
 			   EDP_PSR_DEBUG_MASK_MEMUP |
 			   EDP_PSR_DEBUG_MASK_HPD |
-			   EDP_PSR_DEBUG_MASK_LPSP);
+			   EDP_PSR_DEBUG_MASK_LPSP |
+			   EDP_PSR_DEBUG_MASK_DISP_REG_WRITE);
 	}
 }
 
-- 
2.17.0