drm/msm/dpu: Remove arbitrary limit of 1 interface in DSC topology

When DSC is enabled the number of interfaces is forced to be 1, and
documented that it is a "power-optimal" layout to use two DSC encoders
together with two Layer Mixers.  However, the same layout (two DSC
hard-slice encoders with two LMs) is also used when the display is
fed with data over two instead of one interface (common on 4k@120Hz
smartphone panels with Dual-DSI).  Solve this by simply removing the
num_intf = 1 assignment as the count is already calculated by computing
the number of physical encoders within the virtual encoder.

Fixes: 7e9cc175b159 ("drm/msm/disp/dpu1: Add support for DSC in topology")
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Jessica Zhang <quic_jesszhan@quicinc.com>
Signed-off-by: Marijn Suijten <marijn.suijten@somainline.org>
Patchwork: https://patchwork.freedesktop.org/patch/637649/
Link: https://lore.kernel.org/r/20250217-drm-msm-initial-dualpipe-dsc-fixes-v3-3-913100d6103f@somainline.org
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
index 938d8b05a4cd4d2a926ae68ee9a2b7ee2de69ac4..32992e9525530ea4dec2f46643fc06d40d3bca7b 100644 (file)
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
@@ -689,20 +689,21 @@ static struct msm_display_topology dpu_encoder_get_topology(
 
        if (dsc) {
                /*
-                * Use 2 DSC encoders and 2 layer mixers per single interface
+                * Use 2 DSC encoders, 2 layer mixers and 1 or 2 interfaces
                 * when Display Stream Compression (DSC) is enabled,
                 * and when enough DSC blocks are available.
                 * This is power-optimal and can drive up to (including) 4k
                 * screens.
                 */
-               if (dpu_kms->catalog->dsc_count >= 2) {
+               WARN(topology.num_intf > 2,
+                    "DSC topology cannot support more than 2 interfaces\n");
+               if (intf_count >= 2 || dpu_kms->catalog->dsc_count >= 2) {
                        topology.num_dsc = 2;
                        topology.num_lm = 2;
                } else {
                        topology.num_dsc = 1;
                        topology.num_lm = 1;
                }
-               topology.num_intf = 1;
        }
 
        /*