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

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Date:	Wed, 4 May 2016 09:02:08 +0530
From:	Manish Badarkhe <badarkhe.manish@...il.com>
To:	Pramod Gurav <pramod.gurav@...aro.org>
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 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.

Ok, fine.

>>> @@ -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.

Yes, need to handle __pm_runtime__ errors.

>>
>>> +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.

got it.

>>> +#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.

got it.


Regards
Manish Badarkhe