Revert "drm/i915: Disable DC states for all commits"

This reverts commit 0fc6fea which is
commit a2b6e99 upstream.

It is reported to cause regression issues, so it should be reverted from
the 6.1.y tree for now.

Reported-by: Thorsten Leemhuis <regressions@leemhuis.info>
Link: https://lore.kernel.org/r/f0870e8f-0c66-57fd-f95d-18d014a11939@leemhuis.info
Link: https://gitlab.freedesktop.org/drm/intel/-/issues/8419
Cc: Manasi Navare <navaremanasi@google.com>
Cc: Drew Davenport <ddavenport@chromium.org>
Cc: Jouni Högander <jouni.hogander@intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: gregkh

drivers/gpu/drm/i915/display/intel_display.c

@@ -7123,8 +7123,6 @@ static void intel_update_crtc(struct intel_atomic_state *state,
 
 	intel_fbc_update(state, crtc);
 
-	drm_WARN_ON(&i915->drm, !intel_display_power_is_enabled(i915, POWER_DOMAIN_DC_OFF));
-
 	if (!modeset &&
 	    (new_crtc_state->uapi.color_mgmt_changed ||
 	     new_crtc_state->update_pipe))
@@ -7501,28 +7499,8 @@ static void intel_atomic_commit_tail(struct intel_atomic_state *state)
 	drm_atomic_helper_wait_for_dependencies(&state->base);
 	drm_dp_mst_atomic_wait_for_dependencies(&state->base);
 
-	/*
-	 * During full modesets we write a lot of registers, wait
-	 * for PLLs, etc. Doing that while DC states are enabled
-	 * is not a good idea.
-	 *
-	 * During fastsets and other updates we also need to
-	 * disable DC states due to the following scenario:
-	 * 1. DC5 exit and PSR exit happen
-	 * 2. Some or all _noarm() registers are written
-	 * 3. Due to some long delay PSR is re-entered
-	 * 4. DC5 entry -> DMC saves the already written new
-	 *    _noarm() registers and the old not yet written
-	 *    _arm() registers
-	 * 5. DC5 exit -> DMC restores a mixture of old and
-	 *    new register values and arms the update
-	 * 6. PSR exit -> hardware latches a mixture of old and
-	 *    new register values -> corrupted frame, or worse
-	 * 7. New _arm() registers are finally written
-	 * 8. Hardware finally latches a complete set of new
-	 *    register values, and subsequent frames will be OK again
-	 */
-	wakeref = intel_display_power_get(dev_priv, POWER_DOMAIN_DC_OFF);
+	if (state->modeset)
+		wakeref = intel_display_power_get(dev_priv, POWER_DOMAIN_MODESET);
 
 	intel_atomic_prepare_plane_clear_colors(state);
 
@@ -7661,8 +7639,8 @@ static void intel_atomic_commit_tail(struct intel_atomic_state *state)
 		 * the culprit.
 		 */
 		intel_uncore_arm_unclaimed_mmio_detection(&dev_priv->uncore);
+		intel_display_power_put(dev_priv, POWER_DOMAIN_MODESET, wakeref);
 	}
-	intel_display_power_put(dev_priv, POWER_DOMAIN_DC_OFF, wakeref);
 	intel_runtime_pm_put(&dev_priv->runtime_pm, state->wakeref);
 
 	/*