Re: [PATCH v3 1/3] drm/msm/disp/dpu1: pin 1 crtc to 1 encoder

From: Dmitry Baryshkov
Date: Fri Nov 18 2022 - 07:36:48 EST


On 18/11/2022 15:16, 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)

Signed-off-by: Kalyan Thota <quic_kalyant@xxxxxxxxxxx>
---
drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c | 17 ++++++++++-------
1 file changed, 10 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..4784db8 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
@@ -763,7 +763,7 @@ static int _dpu_kms_drm_obj_init(struct dpu_kms *dpu_kms)
drm_for_each_encoder(encoder, dev)
num_encoders++;
- max_crtc_count = min(catalog->mixer_count, num_encoders);
+ max_crtc_count = num_encoders;
/* Create the planes, keeping track of one primary/cursor per crtc */
for (i = 0; i < catalog->sspp_count; i++) {
@@ -795,22 +795,25 @@ 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 an
+ * encoder. The below warn should help in setting up the catalog
+ */
+ WARN_ON(num_encoders > primary_planes_idx);

WARN_ON(max_crtc_count > primary_planes_idx)

We do not care about encoders number, we care about CRTCs number here.

With that fixed:

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>

/* 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