[Intel-gfx] [PATCH 2/2] drm/i915/dsc: use crtc index for bigjoiner primary/secondary crtc

[Jani Nikula]

Pipe numbering isn't guaranteed to be contiguous; there may be fused off
pipes in the middle. The current bigjoiner primary/secondary crtc lookup
with pipe +/- 1 does not take this into account, and may fail
unexpectedly. Fixing this while using pipe numbering gets complicated.

Switch to using crtc index +/- 1 instead. They are contiguous, and the
crtc lookup neatly handles overflows and underflows. The performance
penalty from the crtc list lookup is neglible.

Fixes: 8a029c113b17 ("drm/i915/dp: Modify VDSC helpers to configure DSC for Bigjoiner slave")
Fixes: d961eb20adb6 ("drm/i915/bigjoiner: atomic commit changes for uncompressed joiner")
Cc: Animesh Manna <animesh.manna at intel.com>
Cc: Manasi Navare <manasi.d.navare at intel.com>
Cc: Vandita Kulkarni <vandita.kulkarni at intel.com>
Signed-off-by: Jani Nikula <jani.nikula at intel.com>
---
 drivers/gpu/drm/i915/display/intel_vdsc.c | 31 +++++++++++------------
 1 file changed, 15 insertions(+), 16 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_vdsc.c b/drivers/gpu/drm/i915/display/intel_vdsc.c
index 1fd81bd3ea09..1d757b040bce 100644
--- a/drivers/gpu/drm/i915/display/intel_vdsc.c
+++ b/drivers/gpu/drm/i915/display/intel_vdsc.c
@@ -1106,30 +1106,29 @@ static i915_reg_t dss_ctl2_reg(const struct intel_crtc_state *crtc_state)
 	return is_pipe_dsc(crtc_state) ? ICL_PIPE_DSS_CTL2(pipe) : DSS_CTL2;
 }
 
-struct intel_crtc *
-intel_dsc_get_bigjoiner_secondary(const struct intel_crtc *primary_crtc)
+static struct intel_crtc *
+get_linked_crtc(const struct intel_crtc *crtc, int index)
 {
-	struct drm_i915_private *i915 = to_i915(primary_crtc->base.dev);
-	enum pipe pipe = primary_crtc->pipe + 1;
+	struct drm_i915_private *i915 = to_i915(crtc->base.dev);
+	struct intel_crtc *linked_crtc;
 
-	if (drm_WARN_ON(&i915->drm, pipe >= I915_MAX_PIPES ||
-			!(INTEL_INFO(i915)->pipe_mask & BIT(pipe))))
-		return NULL;
+	linked_crtc = to_intel_crtc(drm_crtc_from_index(&i915->drm, index));
 
-	return intel_get_crtc_for_pipe(i915, pipe);
+	drm_WARN_ON(&i915->drm, !linked_crtc);
+
+	return linked_crtc;
 }
 
 struct intel_crtc *
-intel_dsc_get_bigjoiner_primary(const struct intel_crtc *secondary_crtc)
+intel_dsc_get_bigjoiner_secondary(const struct intel_crtc *primary_crtc)
 {
-	struct drm_i915_private *i915 = to_i915(secondary_crtc->base.dev);
-	enum pipe pipe = secondary_crtc->pipe - 1;
-
-	if (drm_WARN_ON(&i915->drm, pipe <= INVALID_PIPE ||
-			!(INTEL_INFO(i915)->pipe_mask & BIT(pipe))))
-		return NULL;
+	return get_linked_crtc(primary_crtc, primary_crtc->base.index + 1);
+}
 
-	return intel_get_crtc_for_pipe(i915, pipe);
+struct intel_crtc *
+intel_dsc_get_bigjoiner_primary(const struct intel_crtc *secondary_crtc)
+{
+	return get_linked_crtc(secondary_crtc, secondary_crtc->base.index - 1);
 }
 
 void intel_uncompressed_joiner_enable(const struct intel_crtc_state *crtc_state)
-- 
2.20.1