[SRU][Q][PATCH v2 10/10] drm/i915/psr: Do not unnecessarily remove underrun on idle PSR WA

[AceLan Kao]

From: Jouni Högander <jouni.hogander at intel.com>

BugLink: https://bugs.launchpad.net/bugs/2137613

We are currently removing underrun on idle PSR WA even if it's not
applied. Fix this by checking pkg_c_latency_used on PSR exit as well.

Fixes: 9b1795e9b0ae ("drm/i915/psr: Underrun on idle PSR wa only when pkgc latency > delayed vblank")
Signed-off-by: Jouni Högander <jouni.hogander at intel.com>
Reviewed-by: Uma Shankar <uma.shankar at intel.com>
Link: https://lore.kernel.org/r/20250822105846.1023631-1-jouni.hogander@intel.com
(cherry picked from commit c65ee1b1ffc68e274d6c1cebdf9df09407d180fd)
Signed-off-by: Chia-Lin Kao (AceLan) <acelan.kao at canonical.com>
---
 drivers/gpu/drm/i915/display/intel_psr.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_psr.c b/drivers/gpu/drm/i915/display/intel_psr.c
index b9ac9769f7b2c..068d0f6e7c799 100644
--- a/drivers/gpu/drm/i915/display/intel_psr.c
+++ b/drivers/gpu/drm/i915/display/intel_psr.c
@@ -2170,8 +2170,9 @@ static void intel_psr_exit(struct intel_dp *intel_dp)

 		drm_WARN_ON(display->drm, !(val & EDP_PSR2_ENABLE));
 	} else {
-		if (DISPLAY_VER(display) == 20 ||
-		    IS_DISPLAY_VERx100_STEP(display, 3000, STEP_A0, STEP_B0))
+		if ((DISPLAY_VER(display) == 20 ||
+		     IS_DISPLAY_VERx100_STEP(display, 3000, STEP_A0, STEP_B0)) &&
+			intel_dp->psr.pkg_c_latency_used)
 			intel_dmc_start_pkgc_exit_at_start_of_undelayed_vblank(display,
 								       intel_dp->psr.pipe,
 								       false);
--
2.51.0