drm/i915/psr: Do no mask display register writes on hsw/bdw

hsw/bdw lack the pipe register vs. display register distinction
in their PSR masking capabilities. So to keep our CURSURFLIVE
tricks working we need to just unmask all display register writes
on these platforms. The downside being that any display regitster
(eg. even SWF regs) will cause a PSR exit.

Note that WaMaskMMIOWriteForPSR asks us to mask this on bdw, but
that won't work since we need those CURSURFLIVE tricks. Observations
on actual hardware show that this causes one extra PSR exit ~every
10 seconds, which is pretty much irrelevant. I suspect this is
due to the pcode poking at IPS_CTL. Disabling IPS does not stop it
however, so either I'm wrong or pcode pokes at the register
regardless of whether it's actually trying to enable/disable IPS.
Also when the machine is busy (eg. just running 'find /') these
extra PSR exits cease, which again points at pcode or some other
PM entity as being the culprit.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230609141404.12729-11-ville.syrjala@linux.intel.com
Reviewed-by: Jouni Högander <jouni.hogander@intel.com>

diff --git a/drivers/gpu/drm/i915/display/intel_psr.c b/drivers/gpu/drm/i915/display/intel_psr.c
index 24ab98d..952dbf9 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_psr.c
+++ b/drivers/gpu/drm/i915/display/intel_psr.c
@@ -1393,7 +1393,11 @@ static void intel_psr_enable_source(struct intel_dp *intel_dp,
               EDP_PSR_DEBUG_MASK_LPSP |
               EDP_PSR_DEBUG_MASK_MAX_SLEEP;
 
-       if (DISPLAY_VER(dev_priv) < 11)
+       /*
+        * No separate pipe reg write mask on hsw/bdw, so have to unmask all
+        * registers in order to keep the CURSURFLIVE tricks working :(
+        */
+       if (IS_DISPLAY_VER(dev_priv, 9, 10))
                mask |= EDP_PSR_DEBUG_MASK_DISP_REG_WRITE;
 
        intel_de_write(dev_priv, psr_debug_reg(dev_priv, cpu_transcoder), mask);