[PATCH 1/4] drm/i915/dmc: Don't enable any pipe DMC events

[Ville Syrjala]

From: Ville Syrjälä <ville.syrjala at linux.intel.com>

The pipe DMC seems to be making a mess of things in ADL. Various weird
symptoms have been observed such as missing vblank irqs, typicalle
happening when using multiple displays.

Keep all pipe DMC event handlers disabled until needed (which is never
atm). This is also what Windows does on ADL+.

We can also drop DG2 from disable_all_flip_queue_events() since
on DG2 the pipe DMC is the one that handles the flip queue events.

Cc: stable at vger.kernel.org
Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/8685
Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 drivers/gpu/drm/i915/display/intel_dmc.c | 43 ++++++++++++++++++++++--
 1 file changed, 41 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dmc.c b/drivers/gpu/drm/i915/display/intel_dmc.c
index 63e080e07023..073b85b57679 100644
--- a/drivers/gpu/drm/i915/display/intel_dmc.c
+++ b/drivers/gpu/drm/i915/display/intel_dmc.c
@@ -389,7 +389,7 @@ disable_all_flip_queue_events(struct drm_i915_private *i915)
 	enum intel_dmc_id dmc_id;
 
 	/* TODO: check if the following applies to all D13+ platforms. */
-	if (!IS_DG2(i915) && !IS_TIGERLAKE(i915))
+	if (!IS_TIGERLAKE(i915))
 		return;
 
 	for_each_dmc_id(dmc_id) {
@@ -493,6 +493,45 @@ void intel_dmc_disable_pipe(struct drm_i915_private *i915, enum pipe pipe)
 		intel_de_rmw(i915, PIPEDMC_CONTROL(pipe), PIPEDMC_ENABLE, 0);
 }
 
+static bool is_dmc_evt_ctl_reg(struct drm_i915_private *i915,
+			       enum intel_dmc_id dmc_id, i915_reg_t reg)
+{
+	u32 offset = i915_mmio_reg_offset(reg);
+	u32 start = i915_mmio_reg_offset(DMC_EVT_CTL(i915, dmc_id, 0));
+	u32 end = i915_mmio_reg_offset(DMC_EVT_CTL(i915, dmc_id, DMC_EVENT_HANDLER_COUNT_GEN12));
+
+	return offset >= start && offset < end;
+}
+
+static bool disable_dmc_evt(struct drm_i915_private *i915,
+			    enum intel_dmc_id dmc_id,
+			    i915_reg_t reg, u32 data)
+{
+	if (!is_dmc_evt_ctl_reg(i915, dmc_id, reg))
+		return false;
+
+	/* keep all pipe DMC events disabled by default */
+	if (dmc_id != DMC_FW_MAIN)
+		return true;
+
+	return false;
+}
+
+static u32 dmc_mmiodata(struct drm_i915_private *i915,
+			struct intel_dmc *dmc,
+			enum intel_dmc_id dmc_id, int i)
+{
+	if (disable_dmc_evt(i915, dmc_id,
+			    dmc->dmc_info[dmc_id].mmioaddr[i],
+			    dmc->dmc_info[dmc_id].mmiodata[i]))
+		return REG_FIELD_PREP(DMC_EVT_CTL_TYPE_MASK,
+				      DMC_EVT_CTL_TYPE_EDGE_0_1) |
+			REG_FIELD_PREP(DMC_EVT_CTL_EVENT_ID_MASK,
+				       DMC_EVT_CTL_EVENT_ID_FALSE);
+	else
+		return dmc->dmc_info[dmc_id].mmiodata[i];
+}
+
 /**
  * intel_dmc_load_program() - write the firmware from memory to register.
  * @i915: i915 drm device.
@@ -532,7 +571,7 @@ void intel_dmc_load_program(struct drm_i915_private *i915)
 	for_each_dmc_id(dmc_id) {
 		for (i = 0; i < dmc->dmc_info[dmc_id].mmio_count; i++) {
 			intel_de_write(i915, dmc->dmc_info[dmc_id].mmioaddr[i],
-				       dmc->dmc_info[dmc_id].mmiodata[i]);
+				       dmc_mmiodata(i915, dmc, dmc_id, i));
 		}
 	}
 
-- 
2.41.0