Re: [PATCH 2/3] drm/msm/dsi: move next bridge acquisition to dsi_bind

[Abhinav Kumar]

On 3/9/2024 7:09 AM, Dmitry Baryshkov wrote:
Currently the MSM DSI driver looks for the next bridge during
msm_dsi_modeset_init(). If the bridge is not registered at that point,
this might result in -EPROBE_DEFER, which can be problematic that late
during the device probe process. Move next bridge acquisition to the
dsi_bind state so that probe deferral is returned as early as possible.


But msm_dsi_modeset)init() is also called during msm_drm_bind() only.

What issue are you suggesting will be fixed by moving this from 
msm_drm_bind() to dsi_bind()?

Signed-off-by: Dmitry Baryshkov <dmitry.barysh...@linaro.org>
---
  drivers/gpu/drm/msm/dsi/dsi.c         | 16 ++++++++++++++++
  drivers/gpu/drm/msm/dsi/dsi.h         |  2 ++
  drivers/gpu/drm/msm/dsi/dsi_manager.c |  8 +-------
  3 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/msm/dsi/dsi.c b/drivers/gpu/drm/msm/dsi/dsi.c
index 37c4c07005fe..38f10f7a10d3 100644
--- a/drivers/gpu/drm/msm/dsi/dsi.c
+++ b/drivers/gpu/drm/msm/dsi/dsi.c
@@ -120,6 +120,22 @@ static int dsi_bind(struct device *dev, struct device 
*master, void *data)
        struct msm_drm_private *priv = dev_get_drvdata(master);
        struct msm_dsi *msm_dsi = dev_get_drvdata(dev);
  
+	/*
+        * Next bridge doesn't exist for the secondary DSI host in a bonded
+        * pair.
+        */
+       if (!msm_dsi_is_bonded_dsi(msm_dsi) ||
+           msm_dsi_is_master_dsi(msm_dsi)) {
+               struct drm_bridge *ext_bridge;
+
+               ext_bridge = devm_drm_of_get_bridge(&msm_dsi->pdev->dev,
+                                                   msm_dsi->pdev->dev.of_node, 
1, 0);
+               if (IS_ERR(ext_bridge))
+                       return PTR_ERR(ext_bridge);
+
+               msm_dsi->next_bridge = ext_bridge;
+       }
+
        priv->dsi[msm_dsi->id] = msm_dsi;
  
  	return 0;
diff --git a/drivers/gpu/drm/msm/dsi/dsi.h b/drivers/gpu/drm/msm/dsi/dsi.h
index 2ad9a842c678..0adef65be1de 100644
--- a/drivers/gpu/drm/msm/dsi/dsi.h
+++ b/drivers/gpu/drm/msm/dsi/dsi.h
@@ -38,6 +38,8 @@ struct msm_dsi {
        struct mipi_dsi_host *host;
        struct msm_dsi_phy *phy;
  
+	struct drm_bridge *next_bridge;
+
        struct device *phy_dev;
        bool phy_enabled;
  
diff --git a/drivers/gpu/drm/msm/dsi/dsi_manager.c b/drivers/gpu/drm/msm/dsi/dsi_manager.c
index a7c7f85b73e4..b7c52b14c790 100644
--- a/drivers/gpu/drm/msm/dsi/dsi_manager.c
+++ b/drivers/gpu/drm/msm/dsi/dsi_manager.c
@@ -464,18 +464,12 @@ int msm_dsi_manager_ext_bridge_init(u8 id, struct 
drm_bridge *int_bridge)
        struct msm_dsi *msm_dsi = dsi_mgr_get_dsi(id);
        struct drm_device *dev = msm_dsi->dev;
        struct drm_encoder *encoder;
-       struct drm_bridge *ext_bridge;
        struct drm_connector *connector;
        int ret;
  
-	ext_bridge = devm_drm_of_get_bridge(&msm_dsi->pdev->dev,
-                                           msm_dsi->pdev->dev.of_node, 1, 0);
-       if (IS_ERR(ext_bridge))
-               return PTR_ERR(ext_bridge);
-
        encoder = int_bridge->encoder;
  
-	ret = drm_bridge_attach(encoder, ext_bridge, int_bridge,
+       ret = drm_bridge_attach(encoder, msm_dsi->next_bridge, int_bridge,
                        DRM_BRIDGE_ATTACH_NO_CONNECTOR);
        if (ret)
                return ret;