linux-kernel - Re: [PATCH 1/7] media: hantro: add support for reset lines

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Date:   Tue, 23 Nov 2021 17:36:57 +0100
From:   Andrzej Pietrasiewicz <andrzej.p@...labora.com>
To:     Dan Carpenter <dan.carpenter@...cle.com>
Cc:     Jernej Skrabec <jernej.skrabec@...il.com>,
        linux-media@...r.kernel.org, ezequiel@...guardiasur.com.ar,
        nicolas.dufresne@...labora.com, mchehab@...nel.org,
        robh+dt@...nel.org, mripard@...nel.org, wens@...e.org,
        p.zabel@...gutronix.de, gregkh@...uxfoundation.org,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-sunxi@...ts.linux.dev, linux-kernel@...r.kernel.org,
        linux-staging@...ts.linux.dev
Subject: Re: [PATCH 1/7] media: hantro: add support for reset lines

Hi Dan, hi Jernej,

W dniu 23.11.2021 o 15:59, Dan Carpenter pisze:
> On Tue, Nov 23, 2021 at 12:09:03PM +0100, Andrzej Pietrasiewicz wrote:
>>> diff --git a/drivers/staging/media/hantro/hantro_drv.c b/drivers/staging/media/hantro/hantro_drv.c
>>> index ab2467998d29..8c3de31f51b3 100644
>>> --- a/drivers/staging/media/hantro/hantro_drv.c
>>> +++ b/drivers/staging/media/hantro/hantro_drv.c
>>> @@ -905,6 +905,10 @@ static int hantro_probe(struct platform_device *pdev)
>>>    			return PTR_ERR(vpu->clocks[0].clk);
>>>    	}
>>> +	vpu->resets = devm_reset_control_array_get(&pdev->dev, false, true);
>>> +	if (IS_ERR(vpu->resets))
>>> +		return PTR_ERR(vpu->resets);
>>> +
>>>    	num_bases = vpu->variant->num_regs ?: 1;
>>>    	vpu->reg_bases = devm_kcalloc(&pdev->dev, num_bases,
>>>    				      sizeof(*vpu->reg_bases), GFP_KERNEL);
>>> @@ -978,10 +982,16 @@ static int hantro_probe(struct platform_device *pdev)
>>>    	pm_runtime_use_autosuspend(vpu->dev);
>>>    	pm_runtime_enable(vpu->dev);
>          ^^^^^^^^^^^^^^^^^^^^^^^^^^^
> It looks like this is the pm stuff that we have to unwind on error
> 
>>> +	ret = reset_control_deassert(vpu->resets);
>>> +	if (ret) {
>>> +		dev_err(&pdev->dev, "Failed to deassert resets\n");
>>> +		return ret;
>                  ^^^^^^^^^^
> So this return should be a goto undo_pm_stuff
> 
> 
>>> +	}
>>> +
>>>    	ret = clk_bulk_prepare(vpu->variant->num_clocks, vpu->clocks);
>>>    	if (ret) {
>>>    		dev_err(&pdev->dev, "Failed to prepare clocks\n");
>>> -		return ret;
> 
> And this return should also have been a goto so it's a bug in the
> original code.

So we probably want a separate patch addressing that first, and then
the series proper on top of that.

Regards,

Andrzej

> 
>>> +		goto err_rst_assert;
>>
>> Before your patch is applied if clk_bulk_prepare() fails, we
>> simply return on the spot. After the patch is applied not only
>> do you...
>>
>>>    	}
>>>    	ret = v4l2_device_register(&pdev->dev, &vpu->v4l2_dev);
>>> @@ -1037,6 +1047,8 @@ static int hantro_probe(struct platform_device *pdev)
>>>    	v4l2_device_unregister(&vpu->v4l2_dev);
>>>    err_clk_unprepare:
>>>    	clk_bulk_unprepare(vpu->variant->num_clocks, vpu->clocks);
>>> +err_rst_assert:
>>> +	reset_control_assert(vpu->resets);
>>
>> ...revert the effect of reset_control_deassert(), you also...
>>
>>>    	pm_runtime_dont_use_autosuspend(vpu->dev);
>>>    	pm_runtime_disable(vpu->dev);
>>
>> ... do pm_*() stuff. Is there any reason why this is needed?
> 
> So, yes, it's needed, but you're correct to spot that it's not
> consistent.
> 
> regards,
> dan carpenter
>