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

[Kuogee Hsieh <quic_khsieh@quicinc.com>]

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@quicinc.com> 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@quicinc.com>
>>>> ---
>>>>    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

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)



>>>> +
>>>>        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;
>>>>    }
>
>