Message-ID: <3fad4376-b49f-af4f-f350-8d0e28a93b0c@linaro.org>
Date:   Wed, 26 Jul 2023 02:28:50 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Kuogee Hsieh <quic_khsieh@...cinc.com>,
        Bjorn Andersson <andersson@...nel.org>
Cc:     freedreno@...ts.freedesktop.org, quic_sbillaka@...cinc.com,
        quic_abhinavk@...cinc.com, airlied@...il.com,
        linux-arm-msm@...r.kernel.org, robdclark@...il.com,
        dri-devel@...ts.freedesktop.org, dianders@...omium.org,
        vkoul@...nel.org, agross@...nel.org, daniel@...ll.ch,
        marijn.suijten@...ainline.org, quic_jesszhan@...cinc.com,
        swboyd@...omium.org, sean@...rly.run, linux-kernel@...r.kernel.org
Subject: Re: [Freedreno] [PATCH v1 2/5] drm/msm/dp: incorporate pm_runtime
 framework into DP driver

On 26/07/2023 02:26, Kuogee Hsieh wrote:
> 
> On 7/25/2023 3:33 PM, Dmitry Baryshkov wrote:
>> On 26/07/2023 01:25, Kuogee Hsieh wrote:
>>>
>>> On 7/10/2023 9:22 AM, Kuogee Hsieh wrote:
>>>>
>>>> On 7/8/2023 7:52 PM, Bjorn Andersson wrote:
>>>>> On Fri, Jul 07, 2023 at 04:52:20PM -0700, Kuogee Hsieh wrote:
>>>>>> Incorporating pm runtime framework into DP driver so that power
>>>>>> and clock resource handling can be centralized allowing easier
>>>>>> control of these resources in preparation of registering aux bus
>>>>>> uring probe.
>>>>>>
>>>>>> Signed-off-by: Kuogee Hsieh <quic_khsieh@...cinc.com>
>>>>>> ---
>>>>>>   drivers/gpu/drm/msm/dp/dp_aux.c     |  3 ++
>>>>>>   drivers/gpu/drm/msm/dp/dp_display.c | 75 
>>>>>> +++++++++++++++++++++++++++++--------
>>>>>>   2 files changed, 63 insertions(+), 15 deletions(-)
>>>>>>
>>>>>> diff --git a/drivers/gpu/drm/msm/dp/dp_aux.c 
>>>>>> b/drivers/gpu/drm/msm/dp/dp_aux.c
>>>>>> index 8e3b677..c592064 100644
>>>>>> --- a/drivers/gpu/drm/msm/dp/dp_aux.c
>>>>>> +++ b/drivers/gpu/drm/msm/dp/dp_aux.c
>>>>>> @@ -291,6 +291,7 @@ static ssize_t dp_aux_transfer(struct 
>>>>>> drm_dp_aux *dp_aux,
>>>>>>           return -EINVAL;
>>>>>>       }
>>>>>>   +    pm_runtime_get_sync(dp_aux->dev);
>>>>>>       mutex_lock(&aux->mutex);
>>>>>>       if (!aux->initted) {
>>>>>>           ret = -EIO;
>>>>>> @@ -364,6 +365,8 @@ static ssize_t dp_aux_transfer(struct 
>>>>>> drm_dp_aux *dp_aux,
>>>>>>     exit:
>>>>>>       mutex_unlock(&aux->mutex);
>>>>>> +    pm_runtime_mark_last_busy(dp_aux->dev);
>>>>>> +    pm_runtime_put_autosuspend(dp_aux->dev);
>>>>>>         return ret;
>>>>>>   }
>>>>>> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c 
>>>>>> b/drivers/gpu/drm/msm/dp/dp_display.c
>>>>>> index 76f1395..2c5706a 100644
>>>>>> --- a/drivers/gpu/drm/msm/dp/dp_display.c
>>>>>> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
>>>>>> @@ -309,6 +309,10 @@ 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;
>>>>>> @@ -320,9 +324,8 @@ static void dp_display_unbind(struct device 
>>>>>> *dev, struct device *master,
>>>>>>       struct dp_display_private *dp = 
>>>>>> dev_get_dp_display_private(dev);
>>>>>>       struct msm_drm_private *priv = dev_get_drvdata(master);
>>>>>>   -    /* disable all HPD interrupts */
>>>>>> -    if (dp->core_initialized)
>>>>>> -        dp_catalog_hpd_config_intr(dp->catalog, 
>>>>>> DP_DP_HPD_INT_MASK, false);
>>>>>> +    pm_runtime_dont_use_autosuspend(dev);
>>>>>> +    pm_runtime_disable(dev);
>>>>>>         kthread_stop(dp->ev_tsk);
>>>>>>   @@ -466,10 +469,12 @@ static void dp_display_host_init(struct 
>>>>>> dp_display_private *dp)
>>>>>>           dp->dp_display.connector_type, dp->core_initialized,
>>>>>>           dp->phy_initialized);
>>>>>>   -    dp_power_init(dp->power);
>>>>>> -    dp_ctrl_reset_irq_ctrl(dp->ctrl, true);
>>>>>> -    dp_aux_init(dp->aux);
>>>>>> -    dp->core_initialized = true;
>>>>>> +    if (!dp->core_initialized) {
>>>>>> +        dp_power_init(dp->power);
>>>>>> +        dp_ctrl_reset_irq_ctrl(dp->ctrl, true);
>>>>>> +        dp_aux_init(dp->aux);
>>>>>> +        dp->core_initialized = true;
>>>>> There are two cases that queries core_initialized, both of those are
>>>>> done to avoid accessing the DP block without it first being powered 
>>>>> up.
>>>>> With the introduction of runtime PM, it seems reasonable to just power
>>>>> up the block in those two code paths (and remove the variable).
>>>>>
>>>>>> +    }
>>>>>>   }
>>>>>>     static void dp_display_host_deinit(struct dp_display_private *dp)
>>>>>> @@ -478,10 +483,12 @@ static void dp_display_host_deinit(struct 
>>>>>> dp_display_private *dp)
>>>>>>           dp->dp_display.connector_type, dp->core_initialized,
>>>>>>           dp->phy_initialized);
>>>>>>   -    dp_ctrl_reset_irq_ctrl(dp->ctrl, false);
>>>>>> -    dp_aux_deinit(dp->aux);
>>>>>> -    dp_power_deinit(dp->power);
>>>>>> -    dp->core_initialized = false;
>>>>>> +    if (dp->core_initialized) {
>>>>>> +        dp_ctrl_reset_irq_ctrl(dp->ctrl, false);
>>>>>> +        dp_aux_deinit(dp->aux);
>>>>>> +        dp_power_deinit(dp->power);
>>>>>> +        dp->core_initialized = false;
>>>>>> +    }
>>>>>>   }
>>>>>>     static int dp_display_usbpd_configure_cb(struct device *dev)
>>>>>> @@ -1304,6 +1311,39 @@ static int dp_display_remove(struct 
>>>>>> platform_device *pdev)
>>>>>>       dp_display_deinit_sub_modules(dp);
>>>>>>         platform_set_drvdata(pdev, NULL);
>>>>>> +    pm_runtime_put_sync_suspend(&pdev->dev);
>>>>>> +
>>>>>> +    return 0;
>>>>>> +}
>>>>>> +
>>>>>> +static int dp_pm_runtime_suspend(struct device *dev)
>>>>>> +{
>>>>>> +    struct platform_device *pdev = to_platform_device(dev);
>>>>>> +    struct msm_dp *dp_display = platform_get_drvdata(pdev);
>>>>> platform_get_drvdata() is a wrapper for 
>>>>> dev_get_drvdata(&pdev->dev), so
>>>>> there's no need to resolve the platform_device first...
>>>>>
>>>>>> +    struct dp_display_private *dp;
>>>>>> +
>>>>>> +    dp = container_of(dp_display, struct dp_display_private, 
>>>>>> dp_display);
>>>>>> +
>>>>>> +    dp_display_host_phy_exit(dp);
>>>>>> +    dp_catalog_ctrl_hpd_enable(dp->catalog);
>>>>>> +    dp_display_host_deinit(dp);
>>>>>> +
>>>>>> +    return 0;
>>>>>> +}
>>>>>> +
>>>>>> +static int dp_pm_runtime_resume(struct device *dev)
>>>>>> +{
>>>>>> +    struct platform_device *pdev = to_platform_device(dev);
>>>>>> +    struct msm_dp *dp_display = platform_get_drvdata(pdev);
>>>>>> +    struct dp_display_private *dp;
>>>>>> +
>>>>>> +    dp = container_of(dp_display, struct dp_display_private, 
>>>>>> dp_display);
>>>>>> +
>>>>>> +    dp_display_host_init(dp);
>>>>>> +    if (dp_display->is_edp) {
>>>>>> +        dp_catalog_ctrl_hpd_enable(dp->catalog);
>>>>>> +        dp_display_host_phy_init(dp);
>>>>>> +    }
>>>>>>         return 0;
>>>>>>   }
>>>>>> @@ -1409,6 +1449,7 @@ static int dp_pm_suspend(struct device *dev)
>>>>>>   }
>>>>>>     static const struct dev_pm_ops dp_pm_ops = {
>>>>>> +    SET_RUNTIME_PM_OPS(dp_pm_runtime_suspend, 
>>>>>> dp_pm_runtime_resume, NULL)
>>>>>>       .suspend = dp_pm_suspend,
>>>>>>       .resume =  dp_pm_resume,
>>>>>>   };
>>>>>> @@ -1493,10 +1534,6 @@ static int 
>>>>>> dp_display_get_next_bridge(struct msm_dp *dp)
>>>>>>       aux_bus = of_get_child_by_name(dev->of_node, "aux-bus");
>>>>>>         if (aux_bus && dp->is_edp) {
>>>>>> -        dp_display_host_init(dp_priv);
>>>>>> -        dp_catalog_ctrl_hpd_enable(dp_priv->catalog);
>>>>>> -        dp_display_host_phy_init(dp_priv);
>>>>> I'm probably just missing it, but how do we get here with the host
>>>>> powered up and the phy initialized?
>>>>
>>>> if (!dp->core_initialized)  is at dp_display_host_init()
>>>>
>>>>>
>>>>>> -
>>>>>>           /*
>>>>>>            * The code below assumes that the panel will finish 
>>>>>> probing
>>>>>>            * by the time devm_of_dp_aux_populate_ep_devices() 
>>>>>> returns.
>>>>>> @@ -1604,6 +1641,7 @@ void dp_bridge_atomic_enable(struct 
>>>>>> drm_bridge *drm_bridge,
>>>>>>           dp_hpd_plug_handle(dp_display, 0);
>>>>>>         mutex_lock(&dp_display->event_mutex);
>>>>>> + pm_runtime_get_sync(&dp_display->pdev->dev);
>>>>>>         state = dp_display->hpd_state;
>>>>>>       if (state != ST_DISPLAY_OFF && state != ST_MAINLINK_READY) {
>>>>>> @@ -1684,6 +1722,8 @@ void dp_bridge_atomic_post_disable(struct 
>>>>>> drm_bridge *drm_bridge,
>>>>>>       }
>>>>>>         drm_dbg_dp(dp->drm_dev, "type=%d Done\n", 
>>>>>> dp->connector_type);
>>>>>> +
>>>>>> + pm_runtime_put_sync(&dp_display->pdev->dev);
>>>>>>       mutex_unlock(&dp_display->event_mutex);
>>>>>>   }
>>>>>>   @@ -1723,6 +1763,8 @@ void dp_bridge_hpd_enable(struct 
>>>>>> drm_bridge *bridge)
>>>>>>       struct dp_display_private *dp = container_of(dp_display, 
>>>>>> struct dp_display_private, dp_display);
>>>>>>         mutex_lock(&dp->event_mutex);
>>>>>> +    pm_runtime_get_sync(&dp->pdev->dev);
>>>>>> +
>>>>>>       dp_catalog_ctrl_hpd_enable(dp->catalog);
>>>>>>         /* enable HDP interrupts */
>>>>>> @@ -1744,6 +1786,9 @@ void dp_bridge_hpd_disable(struct drm_bridge 
>>>>>> *bridge)
>>>>>>       dp_catalog_ctrl_hpd_disable(dp->catalog);
>>>>>>         dp_display->internal_hpd = false;
>>>>>> +
>>>>>> +    pm_runtime_mark_last_busy(&dp->pdev->dev);
>>>>>> +    pm_runtime_put_autosuspend(&dp->pdev->dev);
>>>>>>       mutex_unlock(&dp->event_mutex);
>>>>>>   }
>>>>> The runtime_get/put in dp_bridge_hpd_enable() and disable matches my
>>>>> expectations. But in the case that we have an external HPD source, 
>>>>> where
>>>>> will the power be turned on?
>>>>>
>>>>> Note that you can test this on your device by routing the HPD GPIO 
>>>>> to a
>>>>> display-connector instance and wiring this to the DP node. In the same
>>>>> way it's done here:
>>>>>
>>>>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm64/boot/dts/qcom/sa8295p-adp.dts#n28
>>>
>>> at sc7280, gpio-47 has function 2 as dp-hot-plug pin. but it does not 
>>> has function for general purpose pin.
>>
>> It has a 'gpio' function, so that the pin can be used as a generic 
>> GPIO with a dp-connector device.
> function 0 is for PBL_DEBUG2,  which function # should I use?

does `function = "gpio"` work?

>>
>>>
>>> Just curious,  to work with external HPD source,
>>>
>>> 1) which DRM_BRIDGE_OP_xxx should be used for bridge->ops?
>>
>> There is no difference. The drm_bridge_connector will select the 
>> bridges according to the needs. E.g. the dp-connector can provide 
>> DRM_BRIDGE_OP_DETECT / OP_HPD (if the hpd-gpios property is 
>> configured). If it does, it will be selected for detection/HPD 
>> handling. If not, the main dp bridge will handle these operations.
> 
> can you please point me out where  "hpd-gpios" info get parsed and 
> during polling where the gpio status get read from?

Can you please take a look at the display-controller.c driver?

> 
> Thanks,
> 
>>
>>>
>>> 2) are both .hpd_enable and .hpd_disable  have to be populated?
>>
>> No, they are both optional.
>>

-- 
With best wishes
Dmitry

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