Re: [PATCH v1 5/5] drm/msm/dp: move of_dp_aux_populate_bus() to probe for eDP

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On 20/07/2023 23:27, Kuogee Hsieh wrote:

On 7/10/2023 11:24 AM, Dmitry Baryshkov wrote:
[Restored CC list]

On Mon, 10 Jul 2023 at 20:08, Kuogee Hsieh <quic_khsieh@xxxxxxxxxxx> wrote:

On 7/7/2023 5:32 PM, Dmitry Baryshkov wrote:
On 08/07/2023 02:52, Kuogee Hsieh wrote:
Move of_dp_aux_populate_bus() to dp_display_probe() for eDP
from dp_display_bind() so that probe deferral cases can be
handled effectively

Signed-off-by: Kuogee Hsieh <quic_khsieh@xxxxxxxxxxx>
---
   drivers/gpu/drm/msm/dp/dp_aux.c     | 25 ++++++++++++
   drivers/gpu/drm/msm/dp/dp_display.c | 79
+++++++++++++++++++------------------
   2 files changed, 65 insertions(+), 39 deletions(-)

diff --git a/drivers/gpu/drm/msm/dp/dp_aux.c
b/drivers/gpu/drm/msm/dp/dp_aux.c
index c592064..c1baffb 100644
--- a/drivers/gpu/drm/msm/dp/dp_aux.c
+++ b/drivers/gpu/drm/msm/dp/dp_aux.c
@@ -505,6 +505,21 @@ void dp_aux_unregister(struct drm_dp_aux *dp_aux)
       drm_dp_aux_unregister(dp_aux);
   }
   +static int dp_wait_hpd_asserted(struct drm_dp_aux *dp_aux,
+                 unsigned long wait_us)
+{
+    int ret;
+    struct dp_aux_private *aux;
+
+    aux = container_of(dp_aux, struct dp_aux_private, dp_aux);
+
+    pm_runtime_get_sync(aux->dev);
+    ret = dp_catalog_aux_wait_for_hpd_connect_state(aux->catalog);
+    pm_runtime_put_sync(aux->dev);
+
+    return ret;
+}
+
   struct drm_dp_aux *dp_aux_get(struct device *dev, struct dp_catalog
*catalog,
                     bool is_edp)
   {
@@ -528,6 +543,16 @@ struct drm_dp_aux *dp_aux_get(struct device
*dev, struct dp_catalog *catalog,
       aux->catalog = catalog;
       aux->retry_cnt = 0;
   +    /*
+     * Use the drm_dp_aux_init() to use the aux adapter
+     * before registering aux with the DRM device.
+     */
+    aux->dp_aux.name = "dpu_dp_aux";
+    aux->dp_aux.dev = dev;
+    aux->dp_aux.transfer = dp_aux_transfer;
+    aux->dp_aux.wait_hpd_asserted = dp_wait_hpd_asserted;
+    drm_dp_aux_init(&aux->dp_aux);
+
       return &aux->dp_aux;
   }
   diff --git a/drivers/gpu/drm/msm/dp/dp_display.c
b/drivers/gpu/drm/msm/dp/dp_display.c
index 185f1eb..7ed4bea 100644
--- a/drivers/gpu/drm/msm/dp/dp_display.c
+++ b/drivers/gpu/drm/msm/dp/dp_display.c
@@ -302,10 +302,6 @@ static int dp_display_bind(struct device *dev,
struct device *master,
           goto end;
       }
   -    pm_runtime_enable(dev);
-    pm_runtime_set_autosuspend_delay(dev, 1000);
-    pm_runtime_use_autosuspend(dev);
-
       return 0;
   end:
       return rc;
@@ -322,8 +318,6 @@ static void dp_display_unbind(struct device *dev,
struct device *master,
         kthread_stop(dp->ev_tsk);
   -    of_dp_aux_depopulate_bus(dp->aux);
-
       dp_power_client_deinit(dp->power);
       dp_unregister_audio_driver(dev, dp->audio);
       dp_aux_unregister(dp->aux);
@@ -1245,6 +1239,29 @@ static const struct msm_dp_desc
*dp_display_get_desc(struct platform_device *pde
       return NULL;
   }
   +static void of_dp_aux_depopulate_bus_void(void *data)
+{
+    of_dp_aux_depopulate_bus(data);
+}
+
+static int dp_display_auxbus_emulation(struct dp_display_private *dp)
Why is it called emulation?

+{
+    struct device *dev = &dp->pdev->dev;
+    struct device_node *aux_bus;
+    int ret = 0;
+
+    aux_bus = of_get_child_by_name(dev->of_node, "aux-bus");
+
+    if (aux_bus) {
+        ret = devm_of_dp_aux_populate_bus(dp->aux, NULL);
And here you missed the whole point of why we have been asking for.
Please add a sensible `done_probing' callback, which will call
component_add(). This way the DP component will only be registered
when the panel has been probed. Keeping us from the component binding
retries and corresponding side effects.

+
+        devm_add_action_or_reset(dev, of_dp_aux_depopulate_bus_void,
+                     dp->aux);
Useless, it's already handled by the devm_ part of the
devm_of_dp_aux_populate_bus().

+    }
+
+    return ret;
+}
+
   static int dp_display_probe(struct platform_device *pdev)
   {
       int rc = 0;
@@ -1290,8 +1307,18 @@ static int dp_display_probe(struct
platform_device *pdev)
         platform_set_drvdata(pdev, &dp->dp_display);
   +    pm_runtime_enable(&pdev->dev);
+    pm_runtime_set_autosuspend_delay(&pdev->dev, 1000);
+    pm_runtime_use_autosuspend(&pdev->dev);
Can we have this in probe right from the patch #2?
no, at patch#2, devm_of_dp_aux_populate_bus() is done ta bind timing.

The device used by pm_runtime_get_sync() of generic_edp_panel_probe()
which is derived from devm_of_dp_aux_populate_bus() is different the
&pdev->dev here.
Excuse me, I don't get your answer. In patch #2 you have added
pm_runtime_enable() / etc to dp_display_bind().
In this patch you are moving these calls to dp_display_probe(). I
think that the latter is a better place for enabling runtime PM and as
such I've asked you to squash this chunk into patch #2.
Why isn't that going to work?

If I'm not mistaken here, the panel's call to pm_runtime_get_sync()
will wake up the panel and all the parent devices, including the DP.
That's what I meant in my comment regarding PM calls in the patch #1.
pm_runtime_get_sync() / resume() / etc. do not only increase the
runtime PM count. They do other things to parent devices, linked
devices, etc.

sorry for late response,

yes, pm_runtime_enable() at probe() is better and i did that original. but it is not work.

I found that,

1) at dp_display_bind(), dev is mdss

If the 'dev' is the issue, you can always use dp_display_private::pdev.


2) at probe() dev is dp

3) pm_runtime_enable(dp's dev) and generic_edp_panel_probe() --> pm_runtime_get_sync(mdss's dev)

I might be missing something. Please describe, what exactly doesn't work.




+
       dp_display_request_irq(dp);
   +    if (dp->dp_display.is_edp) {
+        rc = dp_display_auxbus_emulation(dp);
+        if (rc)
+            DRM_ERROR("eDP aux-bus emulation failed, rc=%d\n", rc);
+    }
+
       rc = component_add(&pdev->dev, &dp_display_comp_ops);
       if (rc) {
           DRM_ERROR("component add failed, rc=%d\n", rc);
@@ -1306,11 +1333,14 @@ static int dp_display_remove(struct
platform_device *pdev)
       struct dp_display_private *dp =
dev_get_dp_display_private(&pdev->dev);
         component_del(&pdev->dev, &dp_display_comp_ops);
-    dp_display_deinit_sub_modules(dp);
-
       platform_set_drvdata(pdev, NULL);
+
+    pm_runtime_dont_use_autosuspend(&pdev->dev);
+    pm_runtime_disable(&pdev->dev);
       pm_runtime_put_sync_suspend(&pdev->dev);
   +    dp_display_deinit_sub_modules(dp);
+
       return 0;
   }
   @@ -1514,31 +1544,10 @@ void msm_dp_debugfs_init(struct msm_dp
*dp_display, struct drm_minor *minor)
     static int dp_display_get_next_bridge(struct msm_dp *dp)
   {
-    int rc;
+    int rc = 0;
       struct dp_display_private *dp_priv;
-    struct device_node *aux_bus;
-    struct device *dev;
         dp_priv = container_of(dp, struct dp_display_private,
dp_display);
-    dev = &dp_priv->pdev->dev;
-    aux_bus = of_get_child_by_name(dev->of_node, "aux-bus");
-
-    if (aux_bus && dp->is_edp) {
-        /*
-         * The code below assumes that the panel will finish probing
-         * by the time devm_of_dp_aux_populate_ep_devices() returns.
-         * This isn't a great assumption since it will fail if the
-         * panel driver is probed asynchronously but is the best we
-         * can do without a bigger driver reorganization.
-         */
-        rc = of_dp_aux_populate_bus(dp_priv->aux, NULL);
-        of_node_put(aux_bus);
-        if (rc)
-            goto error;
-    } else if (dp->is_edp) {
-        DRM_ERROR("eDP aux_bus not found\n");
-        return -ENODEV;
-    }
         /*
        * External bridges are mandatory for eDP interfaces: one has to
@@ -1551,17 +1560,9 @@ static int dp_display_get_next_bridge(struct
msm_dp *dp)
       if (!dp->is_edp && rc == -ENODEV)
           return 0;
   -    if (!rc) {
+    if (!rc)
           dp->next_bridge = dp_priv->parser->next_bridge;
-        return 0;
-    }
   -error:
-    if (dp->is_edp) {
-        of_dp_aux_depopulate_bus(dp_priv->aux);
-        dp_display_host_phy_exit(dp_priv);
-        dp_display_host_deinit(dp_priv);
-    }
       return rc;
   }



--
With best wishes
Dmitry




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