linux-kernel - Re: [Intel-gfx] [PATCH v10 4/5] mei: gsc: add runtime pm handlers

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Date:   Thu, 10 Mar 2022 14:03:45 -0500
From:   Rodrigo Vivi <rodrigo.vivi@...el.com>
To:     Alexander Usyskin <alexander.usyskin@...el.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Tvrtko Ursulin <tvrtko.ursulin@...ux.intel.com>,
        linux-kernel@...r.kernel.org,
        Tomas Winkler <tomas.winkler@...el.com>,
        Vitaly Lubart <vitaly.lubart@...el.com>,
        intel-gfx@...ts.freedesktop.org
Subject: Re: [Intel-gfx] [PATCH v10 4/5] mei: gsc: add runtime pm handlers

On Tue, Mar 08, 2022 at 06:36:53PM +0200, Alexander Usyskin wrote:
> From: Tomas Winkler <tomas.winkler@...el.com>
> 
> Implement runtime handlers for mei-gsc, to track
> idle state of the device properly.
> 
> CC: Rodrigo Vivi <rodrigo.vivi@...el.com>
> Signed-off-by: Tomas Winkler <tomas.winkler@...el.com>
> Signed-off-by: Alexander Usyskin <alexander.usyskin@...el.com>
> ---
>  drivers/misc/mei/gsc-me.c | 67 ++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 66 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/misc/mei/gsc-me.c b/drivers/misc/mei/gsc-me.c
> index cf427f6fdec9..dac482ddab51 100644
> --- a/drivers/misc/mei/gsc-me.c
> +++ b/drivers/misc/mei/gsc-me.c
> @@ -152,7 +152,72 @@ static int __maybe_unused mei_gsc_pm_resume(struct device *device)
>  	return 0;
>  }
>  
> -static SIMPLE_DEV_PM_OPS(mei_gsc_pm_ops, mei_gsc_pm_suspend, mei_gsc_pm_resume);
> +static int __maybe_unused mei_gsc_pm_runtime_idle(struct device *device)
> +{
> +	struct mei_device *dev = dev_get_drvdata(device);
> +
> +	if (!dev)
> +		return -ENODEV;
> +	if (mei_write_is_idle(dev))
> +		pm_runtime_autosuspend(device);

This is not needed. The _idle() callback is called right before the autosuspend.
so you just need to return -EBUSY if not idle.

But also I'm missing the call to enable the autosuspend and set the delay.

Is this flow really working and you are getting device suspended when not in use?
(Maybe it is just my ignorance on other flow types here)

> +
> +	return -EBUSY;
> +}
> +
> +static int  __maybe_unused mei_gsc_pm_runtime_suspend(struct device *device)
> +{
> +	struct mei_device *dev = dev_get_drvdata(device);
> +	struct mei_me_hw *hw;
> +	int ret;
> +
> +	if (!dev)
> +		return -ENODEV;
> +
> +	mutex_lock(&dev->device_lock);
> +
> +	if (mei_write_is_idle(dev)) {
> +		hw = to_me_hw(dev);
> +		hw->pg_state = MEI_PG_ON;
> +		ret = 0;
> +	} else {
> +		ret = -EAGAIN;
> +	}

probably not needed this here... but it would be good if you use
the runtime_pm{get,put} to protect your write operations as well...

> +
> +	mutex_unlock(&dev->device_lock);
> +
> +	return ret;
> +}
> +
> +static int __maybe_unused mei_gsc_pm_runtime_resume(struct device *device)
> +{
> +	struct mei_device *dev = dev_get_drvdata(device);
> +	struct mei_me_hw *hw;
> +	irqreturn_t irq_ret;
> +
> +	if (!dev)
> +		return -ENODEV;
> +
> +	mutex_lock(&dev->device_lock);
> +
> +	hw = to_me_hw(dev);
> +	hw->pg_state = MEI_PG_OFF;
> +
> +	mutex_unlock(&dev->device_lock);
> +
> +	irq_ret = mei_me_irq_thread_handler(1, dev);
> +	if (irq_ret != IRQ_HANDLED)
> +		dev_err(dev->dev, "thread handler fail %d\n", irq_ret);
> +
> +	return 0;
> +}
> +
> +static const struct dev_pm_ops mei_gsc_pm_ops = {
> +	SET_SYSTEM_SLEEP_PM_OPS(mei_gsc_pm_suspend,
> +				mei_gsc_pm_resume)
> +	SET_RUNTIME_PM_OPS(mei_gsc_pm_runtime_suspend,
> +			   mei_gsc_pm_runtime_resume,
> +			   mei_gsc_pm_runtime_idle)
> +};
>  
>  static const struct auxiliary_device_id mei_gsc_id_table[] = {
>  	{
> -- 
> 2.32.0
>