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

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Date:   Tue, 23 Nov 2021 17:59:33 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Andrzej Pietrasiewicz <andrzej.p@...labora.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

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.

> > +		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