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

[Dmitry Baryshkov <dmitry.baryshkov@linaro.org>]

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@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

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