linux-kernel - [PATCH v5 06/14] drm/msm/dpu: Fail atomic_check if multiple outputs request CDM block

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Message-ID: <20250128-concurrent-wb-v5-6-6464ca5360df@quicinc.com>
Date: Tue, 28 Jan 2025 19:20:38 -0800
From: Jessica Zhang <quic_jesszhan@...cinc.com>
To: Rob Clark <robdclark@...il.com>,
        Dmitry Baryshkov
	<dmitry.baryshkov@...aro.org>,
        <quic_abhinavk@...cinc.com>, Sean Paul
	<sean@...rly.run>,
        Marijn Suijten <marijn.suijten@...ainline.org>,
        "David
 Airlie" <airlied@...il.com>,
        Maarten Lankhorst
	<maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Simona Vetter <simona@...ll.ch>,
        Simona Vetter <simona.vetter@...ll.ch>
CC: <quic_ebharadw@...cinc.com>, <linux-arm-msm@...r.kernel.org>,
        <dri-devel@...ts.freedesktop.org>, <freedreno@...ts.freedesktop.org>,
        <linux-kernel@...r.kernel.org>, Rob Clark <robdclark@...omium.org>,
        Ville Syrjälä <ville.syrjala@...ux.intel.com>,
        "Jessica
 Zhang" <quic_jesszhan@...cinc.com>
Subject: [PATCH v5 06/14] drm/msm/dpu: Fail atomic_check if multiple
 outputs request CDM block

Currently, our hardware only supports a single output using CDM block at
most. Because of this, we cannot support cases where both writeback and DP
output request CDM simultaneously

To avoid this happening when CWB is enabled, change
msm_display_topoloy.needs_cdm into a cdm_requested counter to track how
many outputs are requesting CDM block. Return EINVAL if multiple outputs
are trying to reserve CDM.

Signed-off-by: Jessica Zhang <quic_jesszhan@...cinc.com>
---
Changes in v5:
- Changed check to fail only if multiple outputs are requesting CDM
  simultaneously
---
 drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c |  4 ++--
 drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c      | 12 +++++++++---
 drivers/gpu/drm/msm/disp/dpu1/dpu_rm.h      |  5 +++--
 3 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
index bd6fef8eb8f267cde4ebe1155be39ce69e786967..99db194f5d095e83ac72f2830814e649a25918ef 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
@@ -692,10 +692,10 @@ void dpu_encoder_update_topology(struct drm_encoder *drm_enc,
 		fb = conn_state->writeback_job->fb;
 
 		if (fb && MSM_FORMAT_IS_YUV(msm_framebuffer_format(fb)))
-			topology->needs_cdm = true;
+			topology->cdm_requested++;
 	} else if (disp_info->intf_type == INTF_DP) {
 		if (msm_dp_is_yuv_420_enabled(priv->dp[disp_info->h_tile_instance[0]], adj_mode))
-			topology->needs_cdm = true;
+			topology->cdm_requested++;
 	}
 }
 
diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c
index 0fbb92021b184c4792ddfe059e98b3acf7bc7cc6..dca3107d1e8265a864ac62d6b845d6cb966965ed 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c
@@ -585,7 +585,8 @@ static int _dpu_rm_reserve_dsc(struct dpu_rm *rm,
 
 static int _dpu_rm_reserve_cdm(struct dpu_rm *rm,
 			       struct dpu_global_state *global_state,
-			       uint32_t crtc_id)
+			       uint32_t crtc_id,
+			       const struct msm_display_topology *top)
 {
 	/* try allocating only one CDM block */
 	if (!rm->cdm_blk) {
@@ -593,6 +594,11 @@ static int _dpu_rm_reserve_cdm(struct dpu_rm *rm,
 		return -EIO;
 	}
 
+	if (top->cdm_requested > 1) {
+		DPU_ERROR("More than 1 INTF requesting CDM\n");
+		return -EINVAL;
+	}
+
 	if (global_state->cdm_to_crtc_id) {
 		DPU_ERROR("CDM_0 is already allocated\n");
 		return -EIO;
@@ -629,8 +635,8 @@ static int _dpu_rm_make_reservation(
 	if (ret)
 		return ret;
 
-	if (topology->needs_cdm) {
-		ret = _dpu_rm_reserve_cdm(rm, global_state, crtc_id);
+	if (topology->cdm_requested > 0) {
+		ret = _dpu_rm_reserve_cdm(rm, global_state, crtc_id, topology);
 		if (ret) {
 			DPU_ERROR("unable to find CDM blk\n");
 			return ret;
diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.h b/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.h
index b854e42d319d2c482e4e1732239754979f6950dd..7716c226cd7a270a1bac052dc085f5ed84cb9c26 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.h
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.h
@@ -51,7 +51,8 @@ struct dpu_rm_sspp_requirements {
  * @num_intf:     number of interfaces the panel is mounted on
  * @num_dspp:     number of dspp blocks used
  * @num_dsc:      number of Display Stream Compression (DSC) blocks used
- * @needs_cdm:    indicates whether cdm block is needed for this display topology
+ * @cdm_requested:    indicates how many outputs are requesting cdm block for
+ *                    this display topology
  * @cwb_enabled:  indicates whether CWB is enabled for this display topology
  */
 struct msm_display_topology {
@@ -59,7 +60,7 @@ struct msm_display_topology {
 	u32 num_intf;
 	u32 num_dspp;
 	u32 num_dsc;
-	bool needs_cdm;
+	int cdm_requested;
 	bool cwb_enabled;
 };
 

-- 
2.34.1