linux-kernel - Re: [PATCH v1] i2c: i2c-qcom-geni: Serve transfer during early resume stage

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Date: Fri, 29 Mar 2024 22:54:36 +0100
From: Andi Shyti <andi.shyti@...nel.org>
To: Mukesh Kumar Savaliya <quic_msavaliy@...cinc.com>
Cc: konrad.dybcio@...aro.org, andersson@...nel.org, 
	linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org, linux-i2c@...r.kernel.org, 
	quic_vdadhani@...cinc.com, Vinod Koul <vkoul@...nel.org>
Subject: Re: [PATCH v1] i2c: i2c-qcom-geni: Serve transfer during early
 resume stage

Hi Mukesh,

On Thu, Mar 28, 2024 at 06:07:43PM +0530, Mukesh Kumar Savaliya wrote:
> pm_runtime_get_sync() function fails during PM early resume and returning
> -EACCES because runtime PM for the device is disabled at the early stage
> causing i2c transfer to fail. Make changes to serve transfer with force
> resume.
> 
> 1. Register interrupt with IRQF_EARLY_RESUME and IRQF_NO_SUSPEND flags
>    to avoid timeout of transfer when IRQ is not enabled during early stage.
> 2. Do force resume if pm_runtime_get_sync() is failing after system
>    suspend when runtime PM is not enabled.
> 3. Increment power usage count after forced resume to balance
>    it against regular runtime suspend.
> 
> Co-developed-by: Viken Dadhaniya <quic_vdadhani@...cinc.com>
> Signed-off-by: Viken Dadhaniya <quic_vdadhani@...cinc.com>
> Signed-off-by: Mukesh Kumar Savaliya <quic_msavaliy@...cinc.com>

Is this a fix? O mostly an improvement?

..

>  	gi2c->err = 0;
>  	reinit_completion(&gi2c->done);
> -	ret = pm_runtime_get_sync(gi2c->se.dev);
> -	if (ret < 0) {
> -		dev_err(gi2c->se.dev, "error turning SE resources:%d\n", ret);
> -		pm_runtime_put_noidle(gi2c->se.dev);
> -		/* Set device in suspended since resume failed */
> -		pm_runtime_set_suspended(gi2c->se.dev);
> -		return ret;
> +
> +	if (!pm_runtime_enabled(dev) && gi2c->suspended) {
> +		dev_dbg(gi2c->se.dev, "RT_PM disabled, Do force resume, usage_count:%d\n",

dev

nit: you could leave a space after the ':'.

> +			atomic_read(&dev->power.usage_count));
> +		ret = geni_i2c_force_resume(gi2c);
> +		if (ret)
> +			return ret;
> +	} else {
> +		ret = pm_runtime_get_sync(dev);
> +		if (ret == -EACCES && gi2c->suspended) {
> +			dev_dbg(gi2c->se.dev, "PM get_sync() failed-%d, force resume\n", ret);

dev

> +			ret = geni_i2c_force_resume(gi2c);
> +			if (ret)
> +				return ret;
> +		}

Are we missing some cases here? Do we need a few more else's?

Andi

>  	}
>  
>  	qcom_geni_i2c_conf(gi2c);
> @@ -702,8 +730,15 @@ static int geni_i2c_xfer(struct i2c_adapter *adap,
>  	else
>  		ret = geni_i2c_fifo_xfer(gi2c, msgs, num);
>  
> -	pm_runtime_mark_last_busy(gi2c->se.dev);
> -	pm_runtime_put_autosuspend(gi2c->se.dev);
> +	if (!pm_runtime_enabled(dev) && !gi2c->suspended) {
> +		pm_runtime_put_noidle(dev);
> +		pm_runtime_set_suspended(dev);

this looks like repeated code, how about making it a function?

> +		gi2c->suspended = 0;
> +	} else {
> +		pm_runtime_mark_last_busy(gi2c->se.dev);
> +		pm_runtime_put_autosuspend(gi2c->se.dev);
> +	}
> +
>  	gi2c->cur = NULL;
>  	gi2c->err = 0;
>  	return ret;
> @@ -820,7 +855,7 @@ static int geni_i2c_probe(struct platform_device *pdev)
>  	init_completion(&gi2c->done);
>  	spin_lock_init(&gi2c->lock);
>  	platform_set_drvdata(pdev, gi2c);
> -	ret = devm_request_irq(dev, gi2c->irq, geni_i2c_irq, 0,
> +	ret = devm_request_irq(dev, gi2c->irq, geni_i2c_irq, IRQF_EARLY_RESUME | IRQF_NO_SUSPEND,

Can you provide a bit more information on how an early interrupt
would be handled once the device is resumed?

Thanks,
Andi

>  			       dev_name(dev), gi2c);
>  	if (ret) {
>  		dev_err(dev, "Request_irq failed:%d: err:%d\n",
> -- 
> 2.25.1
>