Re: [PATCH v4 1/3] drm/msm/disp/dpu1: pin 1 crtc to 1 encoder

From: Dmitry Baryshkov
Date: Mon Jan 09 2023 - 19:22:35 EST


On 21/11/2022 11:08, Kalyan Thota wrote:
Pin each crtc with one encoder. This arrangement will
disallow crtc switching between encoders and also will
facilitate to advertise certain features on crtc based
on encoder type.

Changes in v1:
- use drm_for_each_encoder macro while iterating through
encoder list (Dmitry)

Changes in v2:
- make sure no encoder miss to have a crtc (Dmitry)
- revisit various factors in deciding the crtc count
such as num_mixers, num_sspp (Dmitry)

Changes in v3:
- none

Changes in v4:
- use max_crtc_count instead of num_encoders in WARN (Dmitry)

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
Signed-off-by: Kalyan Thota <quic_kalyant@xxxxxxxxxxx>
---
drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c | 18 +++++++++++-------
1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
index 7a5fabc..d967eef 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
@@ -795,22 +796,25 @@ static int _dpu_kms_drm_obj_init(struct dpu_kms *dpu_kms)
primary_planes[primary_planes_idx++] = plane;
}
- max_crtc_count = min(max_crtc_count, primary_planes_idx);
+ /*
+ * All the platforms should have at least 1 primary plane for a
+ * crtc. The below warn should help in setting up the catalog
+ */
+ WARN_ON(max_crtc_count > primary_planes_idx);

This change broke sc7180 support, see https://gitlab.freedesktop.org/drm/msm/-/jobs/34395875

I suggest a quick fix of either disabling WB2 or switching one of cursor SSPPs to a generic one.

/* Create one CRTC per encoder */
- for (i = 0; i < max_crtc_count; i++) {
+ i = 0;
+ drm_for_each_encoder(encoder, dev) {
crtc = dpu_crtc_init(dev, primary_planes[i], cursor_planes[i]);
if (IS_ERR(crtc)) {
ret = PTR_ERR(crtc);
return ret;
}
priv->crtcs[priv->num_crtcs++] = crtc;
+ encoder->possible_crtcs = 1 << drm_crtc_index(crtc);
+ i++;
}
- /* All CRTCs are compatible with all encoders */
- drm_for_each_encoder(encoder, dev)
- encoder->possible_crtcs = (1 << priv->num_crtcs) - 1;
-
return 0;
}

--
With best wishes
Dmitry