linux-kernel - Re: [PATCH v2 1/2] dmaengine: qcom-bam-dma: Add pm

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Message-ID: <CANYu_0uUE7Vtmx8ifLPNC9RpfSPPy-VqUNZAF+UzXCA68WnQcA@mail.gmail.com>
Date:	Tue, 3 May 2016 17:00:17 +0530
From:	Pramod Gurav <pramod.gurav@...aro.org>
To:	Manish Badarkhe <badarkhe.manish@...il.com>
Cc:	vinod.koul@...el.com, Andy Gross <andy.gross@...aro.org>,
	Ulf Hansson <ulf.hansson@...aro.org>, rjw@...ysocki.net,
	linux-arm-msm@...r.kernel.org, linux-pm@...r.kernel.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	dmaengine@...r.kernel.org,
	Stanimir Varbanov <stanimir.varbanov@...aro.org>,
	okaya@...eaurora.org
Subject: Re: [PATCH v2 1/2] dmaengine: qcom-bam-dma: Add pm_runtime support

Hi Manish,

Thanks for review.

On 3 May 2016 at 15:21, Manish Badarkhe <badarkhe.manish@...il.com> wrote:
> Hi Pramod
>
>> @@ -715,10 +724,13 @@ static int bam_resume(struct dma_chan *chan)
>>         struct bam_device *bdev = bchan->bdev;
>>         unsigned long flag;
>>
>> +       pm_runtime_get_sync(bdev->dev);
>>         spin_lock_irqsave(&bchan->vc.lock, flag);
>>         writel_relaxed(0, bam_addr(bdev, bchan->id, BAM_P_HALT));
>>         bchan->paused = 0;
>>         spin_unlock_irqrestore(&bchan->vc.lock, flag);
>> +       pm_runtime_mark_last_busy(bdev->dev);
>> +       pm_runtime_put_autosuspend(bdev->dev);
>>
>>         return 0;
>>  }
>
> Why this function simply return 'success' without any error capture?
>
I should check return of pm_runtime_get_sync.

>> @@ -1252,16 +1278,76 @@ static int bam_dma_remove(struct platform_device *pdev)
>>
>>         tasklet_kill(&bdev->task);
>>
>> +       pm_runtime_get_sync(&pdev->dev);
>>         clk_disable_unprepare(bdev->bamclk);
>> +       pm_runtime_disable(&pdev->dev);
>> +       pm_runtime_put_noidle(&pdev->dev);
>> +       pm_runtime_set_suspended(&pdev->dev);
>> +
>> +       return 0;
>> +}
>
> Why this function simply return 'success' without any error capture?
Need to handle it better.

>
>> +static int bam_dma_runtime_suspend(struct device *dev)
>> +{
>> +       struct bam_device *bdev = dev_get_drvdata(dev);
>> +
>> +       clk_disable(bdev->bamclk);
>> +
>> +       return 0;
>> +}
>
> Why this function simply return 'success' without any error capture?
If probe has succeeded means bdev->bamclk is not NULL and error hence
clk_disable wont return anything.

>
>
>> +#ifdef CONFIG_PM_SLEEP
>> +static int bam_dma_suspend(struct device *dev)
>> +{
>> +       struct bam_device *bdev = dev_get_drvdata(dev);
>> +
>> +       pm_runtime_force_suspend(dev);
>> +
>> +       clk_unprepare(bdev->bamclk);
>>
>>         return 0;
>>  }
>
> Why this function simply return 'success' without any error capture?
Same logic applies here as well, as pm_runtime_force_suspend and
clk_unprepare may not return error in our case once probe is through.

>
> Regards
> Manish Badarkhe