[PATCH] drm/i915/dsc: don't mess up splitter state in joiner or dsc config

[Jani Nikula]

The driver handles splitter (for MSO) and joiner/dsc configuration in
different places. Avoid messing up the splitter state when
enabling/disabling joiner or dsc.

Note: We should probably handle splitter for MSO as well as dual-link
DSI in intel_vdsc.c. Also, we have intel_uncompressed_joiner_enable()
but no corresponding disable.

Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/1668
Signed-off-by: Jani Nikula <jani.nikula at intel.com>

---

I'm not really sure if MSO + bigjoiner is a valid scenario. It certainly
isn't a common scenario. But let's see if this makes the tests work
before preventing the combo.
---
 drivers/gpu/drm/i915/display/intel_ddi.c       |  5 ++---
 drivers/gpu/drm/i915/display/intel_vdsc.c      | 12 +++++++++---
 drivers/gpu/drm/i915/display/intel_vdsc_regs.h |  1 +
 3 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c
index ba7d0a706a20..7411f028fbcf 100644
--- a/drivers/gpu/drm/i915/display/intel_ddi.c
+++ b/drivers/gpu/drm/i915/display/intel_ddi.c
@@ -2416,9 +2416,8 @@ static void intel_ddi_mso_configure(const struct intel_crtc_state *crtc_state)
 			dss1 |= SPLITTER_CONFIGURATION_4_SEGMENT;
 	}
 
-	intel_de_rmw(i915, ICL_PIPE_DSS_CTL1(pipe),
-		     SPLITTER_ENABLE | SPLITTER_CONFIGURATION_MASK |
-		     OVERLAP_PIXELS_MASK, dss1);
+	/* Only touch the splitter */
+	intel_de_rmw(i915, ICL_PIPE_DSS_CTL1(pipe), SPLITTER_STATE, dss1);
 }
 
 static u8 mtl_get_port_width(u8 lane_count)
diff --git a/drivers/gpu/drm/i915/display/intel_vdsc.c b/drivers/gpu/drm/i915/display/intel_vdsc.c
index b9687b7692b8..a8671d3f1d41 100644
--- a/drivers/gpu/drm/i915/display/intel_vdsc.c
+++ b/drivers/gpu/drm/i915/display/intel_vdsc.c
@@ -766,7 +766,9 @@ void intel_uncompressed_joiner_enable(const struct intel_crtc_state *crtc_state)
 		else
 			dss_ctl1_val |= UNCOMPRESSED_JOINER_PRIMARY;
 
-		intel_de_write(dev_priv, dss_ctl1_reg(crtc, crtc_state->cpu_transcoder), dss_ctl1_val);
+		/* Avoid touching the splitter */
+		intel_de_rmw(dev_priv, dss_ctl1_reg(crtc, crtc_state->cpu_transcoder),
+			     ~SPLITTER_STATE, dss_ctl1_val);
 	}
 }
 
@@ -793,7 +795,9 @@ void intel_dsc_enable(const struct intel_crtc_state *crtc_state)
 		if (!intel_crtc_is_joiner_secondary(crtc_state))
 			dss_ctl1_val |= PRIMARY_BIG_JOINER_ENABLE;
 	}
-	intel_de_write(dev_priv, dss_ctl1_reg(crtc, crtc_state->cpu_transcoder), dss_ctl1_val);
+	/* Avoid touching the splitter */
+	intel_de_rmw(dev_priv, dss_ctl1_reg(crtc, crtc_state->cpu_transcoder),
+		     ~SPLITTER_STATE, dss_ctl1_val);
 	intel_de_write(dev_priv, dss_ctl2_reg(crtc, crtc_state->cpu_transcoder), dss_ctl2_val);
 }
 
@@ -805,7 +809,9 @@ void intel_dsc_disable(const struct intel_crtc_state *old_crtc_state)
 	/* Disable only if either of them is enabled */
 	if (old_crtc_state->dsc.compression_enable ||
 	    old_crtc_state->joiner_pipes) {
-		intel_de_write(dev_priv, dss_ctl1_reg(crtc, old_crtc_state->cpu_transcoder), 0);
+		/* Avoid touching the splitter */
+		intel_de_rmw(dev_priv, dss_ctl1_reg(crtc, old_crtc_state->cpu_transcoder),
+			     ~SPLITTER_STATE, 0);
 		intel_de_write(dev_priv, dss_ctl2_reg(crtc, old_crtc_state->cpu_transcoder), 0);
 	}
 }
diff --git a/drivers/gpu/drm/i915/display/intel_vdsc_regs.h b/drivers/gpu/drm/i915/display/intel_vdsc_regs.h
index f921ad67b587..3734cd96f55e 100644
--- a/drivers/gpu/drm/i915/display/intel_vdsc_regs.h
+++ b/drivers/gpu/drm/i915/display/intel_vdsc_regs.h
@@ -37,6 +37,7 @@
 #define  SPLITTER_CONFIGURATION_MASK		REG_GENMASK(26, 25)
 #define  SPLITTER_CONFIGURATION_2_SEGMENT	REG_FIELD_PREP(SPLITTER_CONFIGURATION_MASK, 0)
 #define  SPLITTER_CONFIGURATION_4_SEGMENT	REG_FIELD_PREP(SPLITTER_CONFIGURATION_MASK, 1)
+#define  SPLITTER_STATE				(SPLITTER_ENABLE | SPLITTER_CONFIGURATION_MASK | OVERLAP_PIXELS_MASK)
 #define  UNCOMPRESSED_JOINER_PRIMARY		(1 << 21)
 #define  UNCOMPRESSED_JOINER_SECONDARY		(1 << 20)
 
-- 
2.39.2