drm/i915/xelpd: Fix unclaimed accesses while loading PIPEDMC-C/D

At the moment on DG2 at least loading the DMC firmware's PIPEDMC C and D
programs leads to sporadic unclaimed register accesses while programming
the initial state as described by the firmware's "MMIO init" table. This
will also lead to later unclaimed accesses for unrelated transcoder/pipe
registers backed by the pipe C and D display power wells.

Disabling the PIPEDMC clock gating during initialization - similarly to
Wa_16015201720 fixed this problem in my tests. While pipe A an B
requires the clock gating to be disabled all the time pipe C and D
requires this only while accessing the PIPEDMC registers.

Bspec: 49193
References: https://gitlab.freedesktop.org/drm/intel/-/issues/6526
References: https://gitlab.freedesktop.org/drm/intel/-/issues/6308
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Arun R Murthy <arun.r.murthy@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220808103054.3586074-1-imre.deak@intel.com

diff --git a/drivers/gpu/drm/i915/display/intel_display_power.c b/drivers/gpu/drm/i915/display/intel_display_power.c
index 3f84af6beff31d7a32908cf3b73a0b2e8fb152df..e42797e1655daa8a5e4262a5f60aee538a6c04c4 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_display_power.c
+++ b/drivers/gpu/drm/i915/display/intel_display_power.c
@@ -1615,14 +1615,6 @@ static void icl_display_core_init(struct drm_i915_private *dev_priv,
                intel_de_rmw(dev_priv, SOUTH_DSPCLK_GATE_D, 0,
                             PCH_DPMGUNIT_CLOCK_GATE_DISABLE);
 
-       /* Wa_16015201720:adl-p,dg2 */
-       if (DISPLAY_VER(dev_priv) == 13) {
-               intel_de_rmw(dev_priv, CLKGATE_DIS_PSL_EXT(PIPE_A),
-                            0, PIPEDMC_GATING_DIS);
-               intel_de_rmw(dev_priv, CLKGATE_DIS_PSL_EXT(PIPE_B),
-                            0, PIPEDMC_GATING_DIS);
-       }
-
        /* 1. Enable PCH reset handshake. */
        intel_pch_reset_handshake(dev_priv, !HAS_PCH_NOP(dev_priv));
 

diff --git a/drivers/gpu/drm/i915/display/intel_dmc.c b/drivers/gpu/drm/i915/display/intel_dmc.c
index 00e18a4a5a5a45b6c093a81df830fa7c1b95eee0..6c35212c36256a8a40cb3fbe7e9d98e2e389da16 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_dmc.c
+++ b/drivers/gpu/drm/i915/display/intel_dmc.c
@@ -383,6 +383,30 @@ static void disable_all_event_handlers(struct drm_i915_private *i915)
        }
 }
 
+static void pipedmc_clock_gating_wa(struct drm_i915_private *i915, bool enable)
+{
+       enum pipe pipe;
+
+       if (DISPLAY_VER(i915) != 13)
+               return;
+
+       /*
+        * Wa_16015201720:adl-p,dg2
+        * The WA requires clock gating to be disabled all the time
+        * for pipe A and B.
+        * For pipe C and D clock gating needs to be disabled only
+        * during initializing the firmware.
+        */
+       if (enable)
+               for (pipe = PIPE_A; pipe <= PIPE_D; pipe++)
+                       intel_de_rmw(i915, CLKGATE_DIS_PSL_EXT(pipe),
+                                    0, PIPEDMC_GATING_DIS);
+       else
+               for (pipe = PIPE_C; pipe <= PIPE_D; pipe++)
+                       intel_de_rmw(i915, CLKGATE_DIS_PSL_EXT(pipe),
+                                    PIPEDMC_GATING_DIS, 0);
+}
+
 /**
  * intel_dmc_load_program() - write the firmware from memory to register.
  * @dev_priv: i915 drm device.
@@ -399,6 +423,8 @@ void intel_dmc_load_program(struct drm_i915_private *dev_priv)
        if (!intel_dmc_has_payload(dev_priv))
                return;
 
+       pipedmc_clock_gating_wa(dev_priv, true);
+
        disable_all_event_handlers(dev_priv);
 
        assert_rpm_wakelock_held(&dev_priv->runtime_pm);
@@ -432,6 +458,8 @@ void intel_dmc_load_program(struct drm_i915_private *dev_priv)
         * here.
         */
        disable_all_flip_queue_events(dev_priv);
+
+       pipedmc_clock_gating_wa(dev_priv, false);
 }
 
 /**
@@ -446,7 +474,9 @@ void intel_dmc_disable_program(struct drm_i915_private *i915)
        if (!intel_dmc_has_payload(i915))
                return;
 
+       pipedmc_clock_gating_wa(i915, true);
        disable_all_event_handlers(i915);
+       pipedmc_clock_gating_wa(i915, false);
 }
 
 void assert_dmc_loaded(struct drm_i915_private *i915)