[PATCH 2/5] drm/msm/dpu: don't count the cloned writeback as an interface

[Dmitry Baryshkov]

In the clone mode dpu_encoder_update_topology() is called both for the
real-time and for the writeback encoder, so topology.num_intf also
counts the writeback. However the cloned writeback has no datapath of
its own, it taps the mixers of the real-time encoder. Each user of
num_intf has to compensate for that, and not all of them get it right:

- dpu_crtc_get_topology() skips the "two interfaces use two mixers"
  rule if CWB is enabled, so a dual-DSI display in the clone mode gets
  a single mixer for its two interfaces if the mode is narrow enough;

- _dpu_rm_reserve_dsc() compares num_dsc to num_intf to detect the DSC
  merge, so it doesn't allocate a DSC pair for a single DSI interface
  using two DSC blocks while being cloned.

Count only the real-time interfaces if the CRTC is in the clone mode.
The standalone writeback is still counted as an interface.

Assisted-by: LLM
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxxxxxxxx>
---
 drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c    | 13 +++----------
 drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c |  8 +++-----
 2 files changed, 6 insertions(+), 15 deletions(-)

diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
index 42d0a529b4d5..828187f46eae 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
@@ -1385,12 +1385,12 @@ static struct msm_display_topology dpu_crtc_get_topology(
 	struct msm_display_topology topology = {0};
 	struct drm_encoder *drm_enc;
 
+	topology.cwb_enabled = drm_crtc_in_clone_mode(crtc_state);
+
 	drm_for_each_encoder_mask(drm_enc, crtc->dev, crtc_state->encoder_mask)
 		dpu_encoder_update_topology(drm_enc, &topology, crtc_state->state,
 					    &crtc_state->adjusted_mode);
 
-	topology.cwb_enabled = drm_crtc_in_clone_mode(crtc_state);
-
 	/*
 	 * Datapath topology selection
 	 *
@@ -1404,16 +1404,9 @@ static struct msm_display_topology dpu_crtc_get_topology(
 	 * If DSC is enabled, use 2 LMs for 2:2:1 topology
 	 *
 	 * Add dspps to the reservation requirements if ctm or gamma_lut are requested
-	 *
-	 * Only hardcode num_lm to 2 for cases where num_intf == 2 and CWB is not
-	 * enabled. This is because in cases where CWB is enabled, num_intf will
-	 * count both the WB and real-time phys encoders.
-	 *
-	 * For non-DSC CWB usecases, have the num_lm be decided by the
-	 * (mode->hdisplay > MAX_HDISPLAY_SPLIT) check.
 	 */
 
-	if (topology.num_intf == 2 && !topology.cwb_enabled)
+	if (topology.num_intf == 2)
 		topology.num_lm = 2;
 	else if (topology.num_dsc == 2)
 		topology.num_lm = 2;
diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
index 5a06a0fbc7e1..65161efc4294 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
@@ -667,11 +667,9 @@ void dpu_encoder_update_topology(struct drm_encoder *drm_enc,
 	struct drm_framebuffer *fb;
 	struct drm_dsc_config *dsc;
 
-	int i;
-
-	for (i = 0; i < MAX_PHYS_ENCODERS_PER_VIRTUAL; i++)
-		if (dpu_enc->phys_encs[i])
-			topology->num_intf++;
+	/* a cloned writeback taps the datapath of the real-time encoder */
+	if (!topology->cwb_enabled || disp_info->intf_type != INTF_WB)
+		topology->num_intf += dpu_enc->num_phys_encs;
 
 	dsc = dpu_encoder_get_dsc_config(drm_enc);
 

-- 
2.47.3