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

[Kuogee Hsieh <quic_khsieh@xxxxxxxxxxx>]

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

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;
> > > >    }