drm/i915: Get PM ref before accessing HW register

Seeing these errors when GT is likely in suspend state-
"RPM wakelock ref not held during HW access"

Ensure GT is awake before trying to access HW registers. Avoid
reading the register if that is not the case.

Signed-off-by: Vinay Belgaumkar <vinay.belgaumkar@intel.com>
Fixes: 41e5c17ebfc2 ("drm/i915/guc/slpc: Sysfs hooks for SLPC")
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210907232704.12982-1-vinay.belgaumkar@intel.com
(cherry picked from commit f25e3908b9cd4a3fe819e9bdcdde58f20bacb34c)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

diff --git a/drivers/gpu/drm/i915/gt/intel_rps.c b/drivers/gpu/drm/i915/gt/intel_rps.c
index d812b27835f8ce8f9388f7e0b018025684215106..591a5224287ea83475df1184855e8a34bc6478f3 100644 (file)
--- a/drivers/gpu/drm/i915/gt/intel_rps.c
+++ b/drivers/gpu/drm/i915/gt/intel_rps.c
@@ -1973,8 +1973,14 @@ u32 intel_rps_read_actual_frequency(struct intel_rps *rps)
 u32 intel_rps_read_punit_req(struct intel_rps *rps)
 {
        struct intel_uncore *uncore = rps_to_uncore(rps);
+       struct intel_runtime_pm *rpm = rps_to_uncore(rps)->rpm;
+       intel_wakeref_t wakeref;
+       u32 freq = 0;
 
-       return intel_uncore_read(uncore, GEN6_RPNSWREQ);
+       with_intel_runtime_pm_if_in_use(rpm, wakeref)
+               freq = intel_uncore_read(uncore, GEN6_RPNSWREQ);
+
+       return freq;
 }
 
 static u32 intel_rps_get_req(u32 pureq)