Re: [PATCH v3] drm/msm/dp: employ bridge mechanism for display enable and disable

From: Kuogee Hsieh
Date: Mon Nov 29 2021 - 11:59:15 EST



On 11/24/2021 11:45 AM, Dmitry Baryshkov wrote:
On 15/11/2021 21:48, Kuogee Hsieh wrote:
Currently the msm_dp_*** functions implement the same sequence which would
happen when drm_bridge is used. hence get rid of this intermediate layer
and align with the drm_bridge usage to avoid customized implementation.

Signed-off-by: Kuogee Hsieh <quic_khsieh@xxxxxxxxxxx>

Changes in v2:
-- revise commit text
-- rename dp_bridge to msm_dp_bridge
-- delete empty functions

Changes in 3:
-- replace kzalloc() with devm_kzalloc()
-- replace __dp_display_enable() with dp_display_enable()
-- replace __dp_display_disable() with dp_display_disable()
---
  drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 21 -------
  drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c     |  7 +++
  drivers/gpu/drm/msm/dp/dp_display.c         |  4 +-
  drivers/gpu/drm/msm/dp/dp_display.h         |  1 +
  drivers/gpu/drm/msm/dp/dp_drm.c             | 91 +++++++++++++++++++++++++++++
  drivers/gpu/drm/msm/msm_drv.h               | 16 +++--
  6 files changed, 113 insertions(+), 27 deletions(-)

diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
index 31050aa..c4e08c4 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
@@ -1003,9 +1003,6 @@ static void dpu_encoder_virt_mode_set(struct drm_encoder *drm_enc,
        trace_dpu_enc_mode_set(DRMID(drm_enc));
  -    if (drm_enc->encoder_type == DRM_MODE_ENCODER_TMDS)
-        msm_dp_display_mode_set(dpu_enc->dp, drm_enc, mode, adj_mode);
-
      list_for_each_entry(conn_iter, connector_list, head)
          if (conn_iter->encoder == drm_enc)
              conn = conn_iter;
@@ -1181,14 +1178,6 @@ static void dpu_encoder_virt_enable(struct drm_encoder *drm_enc)
        _dpu_encoder_virt_enable_helper(drm_enc);
  -    if (drm_enc->encoder_type == DRM_MODE_ENCODER_TMDS) {
-        ret = msm_dp_display_enable(dpu_enc->dp, drm_enc);
-        if (ret) {
-            DPU_ERROR_ENC(dpu_enc, "dp display enable failed: %d\n",
-                ret);
-            goto out;
-        }
-    }
      dpu_enc->enabled = true;
    out:
@@ -1214,11 +1203,6 @@ static void dpu_encoder_virt_disable(struct drm_encoder *drm_enc)
      /* wait for idle */
      dpu_encoder_wait_for_event(drm_enc, MSM_ENC_TX_COMPLETE);
  -    if (drm_enc->encoder_type == DRM_MODE_ENCODER_TMDS) {
-        if (msm_dp_display_pre_disable(dpu_enc->dp, drm_enc))
-            DPU_ERROR_ENC(dpu_enc, "dp display push idle failed\n");
-    }
-
      dpu_encoder_resource_control(drm_enc, DPU_ENC_RC_EVENT_PRE_STOP);
        for (i = 0; i < dpu_enc->num_phys_encs; i++) {
@@ -1243,11 +1227,6 @@ static void dpu_encoder_virt_disable(struct drm_encoder *drm_enc)
        DPU_DEBUG_ENC(dpu_enc, "encoder disabled\n");
  -    if (drm_enc->encoder_type == DRM_MODE_ENCODER_TMDS) {
-        if (msm_dp_display_disable(dpu_enc->dp, drm_enc))
-            DPU_ERROR_ENC(dpu_enc, "dp display disable failed\n");
-    }
-
      mutex_unlock(&dpu_enc->enc_lock);
  }
  diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
index 27d98b5..d16337f 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
@@ -557,6 +557,13 @@ static int _dpu_kms_initialize_displayport(struct drm_device *dev,
                    encoder->base.id, rc);
              return rc;
          }
+
+        rc = msm_dp_bridge_init(priv->dp[i], dev, encoder);
+        if (rc) {
+            DPU_ERROR("failed to setup DPU bridge %d: rc:%d\n",
+                encoder->base.id, rc);
+            return rc;
+        }

There is no need to teach DPU driver about all the gory details of DP internals. Move this call to the msm_dp_modeset_init().

This has been done at v4.

I will submit v5 to address other commands.


      }
        return rc;
diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
index 2f113ff..51770a4 100644
--- a/drivers/gpu/drm/msm/dp/dp_display.c
+++ b/drivers/gpu/drm/msm/dp/dp_display.c
@@ -1674,8 +1674,8 @@ int msm_dp_display_disable(struct msm_dp *dp, struct drm_encoder *encoder)
  }
    void msm_dp_display_mode_set(struct msm_dp *dp, struct drm_encoder *encoder,
-                struct drm_display_mode *mode,
-                struct drm_display_mode *adjusted_mode)
+                const struct drm_display_mode *mode,
+                const struct drm_display_mode *adjusted_mode)
  {
      struct dp_display_private *dp_display;
  diff --git a/drivers/gpu/drm/msm/dp/dp_display.h b/drivers/gpu/drm/msm/dp/dp_display.h
index 76f45f9..2237e80 100644
--- a/drivers/gpu/drm/msm/dp/dp_display.h
+++ b/drivers/gpu/drm/msm/dp/dp_display.h
@@ -13,6 +13,7 @@
  struct msm_dp {
      struct drm_device *drm_dev;
      struct device *codec_dev;
+    struct drm_bridge *bridge;
      struct drm_connector *connector;
      struct drm_encoder *encoder;
      struct drm_panel *drm_panel;
diff --git a/drivers/gpu/drm/msm/dp/dp_drm.c b/drivers/gpu/drm/msm/dp/dp_drm.c
index f33e315..b341f1f 100644
--- a/drivers/gpu/drm/msm/dp/dp_drm.c
+++ b/drivers/gpu/drm/msm/dp/dp_drm.c
@@ -5,12 +5,21 @@
    #include <drm/drm_atomic_helper.h>
  #include <drm/drm_atomic.h>
+#include <drm/drm_bridge.h>
  #include <drm/drm_crtc.h>
    #include "msm_drv.h"
  #include "msm_kms.h"
  #include "dp_drm.h"
  +
+struct msm_dp_bridge {
+    struct drm_bridge bridge;
+    struct msm_dp *dp_display;
+};
+
+#define to_dp_display(x)     container_of((x), struct msm_dp_bridge, bridge)
+
  struct dp_connector {
      struct drm_connector base;
      struct msm_dp *dp_display;
@@ -162,3 +171,85 @@ struct drm_connector *dp_drm_connector_init(struct msm_dp *dp_display)
        return connector;
  }
+
+static int dp_bridge_attach(struct drm_bridge *drm_bridge,
+                enum drm_bridge_attach_flags flags)
+{
+    return 0;
+}

As far as I see from drm_bridge_attach() there is no need to provide stubs for attach callback. Please drop it.

+
+static void dp_bridge_mode_set(struct drm_bridge *drm_bridge,
+                const struct drm_display_mode *mode,
+                const struct drm_display_mode *adjusted_mode)
+{
+    struct msm_dp_bridge *dp_bridge = to_dp_display(drm_bridge);
+    struct msm_dp *dp_display = dp_bridge->dp_display;
+
+    msm_dp_display_mode_set(dp_display, drm_bridge->encoder, mode, adjusted_mode);
+}
+
+static void dp_bridge_enable(struct drm_bridge *drm_bridge)
+{
+    struct msm_dp_bridge *dp_bridge = to_dp_display(drm_bridge);
+    struct msm_dp *dp_display = dp_bridge->dp_display;
+
+    msm_dp_display_enable(dp_display, drm_bridge->encoder);
+}
+
+static void dp_bridge_disable(struct drm_bridge *drm_bridge)
+{
+    struct msm_dp_bridge *dp_bridge = to_dp_display(drm_bridge);
+    struct msm_dp *dp_display = dp_bridge->dp_display;
+
+    msm_dp_display_pre_disable(dp_display, drm_bridge->encoder);
+}
+
+static void dp_bridge_post_disable(struct drm_bridge *drm_bridge)
+{
+    struct msm_dp_bridge *dp_bridge = to_dp_display(drm_bridge);
+    struct msm_dp *dp_display = dp_bridge->dp_display;
+
+    msm_dp_display_disable(dp_display, drm_bridge->encoder);
+}
+
+static const struct drm_bridge_funcs dp_bridge_ops = {
+    .attach       = dp_bridge_attach,
+    .mode_fixup   = NULL,
+    .pre_enable   = NULL,

No need to initialize fields to default values (NULL). Drop these two please.

+    .enable       = dp_bridge_enable,
+    .disable      = dp_bridge_disable,
+    .post_disable = dp_bridge_post_disable,
+    .mode_set     = dp_bridge_mode_set,
+};
+
+int msm_dp_bridge_init(struct msm_dp *dp_display, struct drm_device *dev,
+            struct drm_encoder *encoder)
+{
+    int rc;
+    struct msm_drm_private *priv;
+    struct msm_dp_bridge *dp_bridge;
+    struct drm_bridge *bridge;
+
+    dp_bridge = devm_kzalloc(dev->dev, sizeof(*dp_bridge), GFP_KERNEL);
+    if (!dp_bridge)
+        return -ENOMEM;
+
+    dp_bridge->dp_display = dp_display;
+
+    bridge = &dp_bridge->bridge;
+    bridge->funcs = &dp_bridge_ops;
+    bridge->encoder = encoder;
+
+    rc = drm_bridge_attach(encoder, bridge, NULL, DRM_BRIDGE_ATTACH_NO_CONNECTOR);
+    if (rc) {
+        DRM_ERROR("failed to attach bridge, rc=%d\n", rc);
+        kfree(dp_bridge);
+        return rc;
+    }
+
+    priv = dev->dev_private;
+    priv->bridges[priv->num_bridges++] = bridge;
+    dp_display->bridge = bridge;
+
+    return 0;
+} > diff --git a/drivers/gpu/drm/msm/msm_drv.h
b/drivers/gpu/drm/msm/msm_drv.h
index 4bb797e..9a2092f 100644
--- a/drivers/gpu/drm/msm/msm_drv.h
+++ b/drivers/gpu/drm/msm/msm_drv.h
@@ -388,8 +388,10 @@ int msm_dp_display_enable(struct msm_dp *dp, struct drm_encoder *encoder);
  int msm_dp_display_disable(struct msm_dp *dp, struct drm_encoder *encoder);
  int msm_dp_display_pre_disable(struct msm_dp *dp, struct drm_encoder *encoder);
  void msm_dp_display_mode_set(struct msm_dp *dp, struct drm_encoder *encoder,
-                struct drm_display_mode *mode,
-                struct drm_display_mode *adjusted_mode);
+                const struct drm_display_mode *mode,
+                const struct drm_display_mode *adjusted_mode);
+int msm_dp_bridge_init(struct msm_dp *dp_display, struct drm_device *dev,
+            struct drm_encoder *encoder);
  void msm_dp_irq_postinstall(struct msm_dp *dp_display);
  void msm_dp_snapshot(struct msm_disp_state *disp_state, struct msm_dp *dp_display);
  @@ -426,10 +428,16 @@ static inline int msm_dp_display_pre_disable(struct msm_dp *dp,
  }
  static inline void msm_dp_display_mode_set(struct msm_dp *dp,
                  struct drm_encoder *encoder,
-                struct drm_display_mode *mode,
-                struct drm_display_mode *adjusted_mode)
+                const struct drm_display_mode *mode,
+                const struct drm_display_mode *adjusted_mode)
  {
  }
+static inline int msm_dp_bridge_init(struct msm_dp *dp_display,
+                struct drm_device *dev,
+                struct drm_encoder *encoder)
+{
+    return -EINVAL;
+}

If msm_dp_bridge_init() becomes DP-internal function, this is unnecessary.

    static inline void msm_dp_irq_postinstall(struct msm_dp *dp_display)
  {