[PATCH 4/6] drm/i915/adlp+: Add DSC early pixel count scaling WA (Wa_1409098942)

[Imre Deak]

Add a workaround to fix timing issues on links with DSC enabled -
presumedly related to the audio functionality.

Bspec requires enabling this workaround if audio is enabled on ADLP,
however Windows enables it whenever DSC is enabled ADLP onwards; follow
Windows.

Bspec: 50490, 55424

Signed-off-by: Imre Deak <imre.deak at intel.com>
---
 drivers/gpu/drm/i915/display/intel_display.c | 13 +++++++++++++
 drivers/gpu/drm/i915/i915_reg.h              |  3 +++
 2 files changed, 16 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
index a92e959c8ac7b..0f4cd634d7dce 100644
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -435,6 +435,14 @@ void intel_enable_transcoder(const struct intel_crtc_state *new_crtc_state)
 		return;
 	}
 
+	/* Wa_1409098942: adlp+ */
+	if (DISPLAY_VER(dev_priv) >= 13 &&
+	    new_crtc_state->dsc.compression_enable) {
+		val &= ~TRANSCONF_PIXEL_COUNT_SCALING_MASK;
+		val |= REG_FIELD_PREP(TRANSCONF_PIXEL_COUNT_SCALING_MASK,
+				      TRANSCONF_PIXEL_COUNT_SCALING_X4);
+	}
+
 	intel_de_write(dev_priv, TRANSCONF(cpu_transcoder),
 		       val | TRANSCONF_ENABLE);
 	intel_de_posting_read(dev_priv, TRANSCONF(cpu_transcoder));
@@ -481,6 +489,11 @@ void intel_disable_transcoder(const struct intel_crtc_state *old_crtc_state)
 	if (!IS_I830(dev_priv))
 		val &= ~TRANSCONF_ENABLE;
 
+	/* Wa_1409098942: adlp+ */
+	if (DISPLAY_VER(dev_priv) >= 13 &&
+	    old_crtc_state->dsc.compression_enable)
+		val &= ~TRANSCONF_PIXEL_COUNT_SCALING_MASK;
+
 	intel_de_write(dev_priv, TRANSCONF(cpu_transcoder), val);
 
 	if (DISPLAY_VER(dev_priv) >= 12)
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index eecbdecb8ed40..b43d1145fa22f 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -2588,6 +2588,9 @@
 #define   TRANSCONF_DITHER_TYPE_ST1		REG_FIELD_PREP(TRANSCONF_DITHER_TYPE_MASK, 1)
 #define   TRANSCONF_DITHER_TYPE_ST2		REG_FIELD_PREP(TRANSCONF_DITHER_TYPE_MASK, 2)
 #define   TRANSCONF_DITHER_TYPE_TEMP		REG_FIELD_PREP(TRANSCONF_DITHER_TYPE_MASK, 3)
+#define   TRANSCONF_PIXEL_COUNT_SCALING_MASK	REG_GENMASK(1, 0)
+#define   TRANSCONF_PIXEL_COUNT_SCALING_X4	1
+
 #define _PIPEASTAT		0x70024
 #define   PIPE_FIFO_UNDERRUN_STATUS		(1UL << 31)
 #define   SPRITE1_FLIP_DONE_INT_EN_VLV		(1UL << 30)
-- 
2.39.2