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

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Message-ID: <9986998.nUPlyArG6x@kista>
Date:   Tue, 23 Nov 2021 17:46:30 +0100
From:   Jernej Škrabec <jernej.skrabec@...il.com>
To:     Dan Carpenter <dan.carpenter@...cle.com>,
        Andrzej Pietrasiewicz <andrzej.p@...labora.com>
Cc:     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: Re: [PATCH 1/7] media: hantro: add support for reset lines

Hi all,

Dne torek, 23. november 2021 ob 17:36:57 CET je Andrzej Pietrasiewicz 
napisal(a):
> 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.

I was just about to suggest that.

Other drivers usually enable PM last, so they don't have PM calls in unwind 
code. However, I think current approach is just as valid (with a fix).

Best regards,
Jernej

> 
> 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
> > 
> 
>