linux-kernel - Re: [PATCH 2/4] dmaengine: sh: rz-dmac: Use devm_add_action_or

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Message-ID: <7b610a06e17e1c816a0a760bb661dbfd20ec44f4.camel@pengutronix.de>
Date: Fri, 05 Sep 2025 17:30:31 +0200
From: Philipp Zabel <p.zabel@...gutronix.de>
To: Tommaso Merciai <tommaso.merciai.xr@...renesas.com>
Cc: tomm.merciai@...il.com, linux-renesas-soc@...r.kernel.org, 
 biju.das.jz@...renesas.com, Vinod Koul <vkoul@...nel.org>, Geert
 Uytterhoeven <geert+renesas@...der.be>, Fabrizio Castro
 <fabrizio.castro.jz@...esas.com>,  Lad Prabhakar
 <prabhakar.mahadev-lad.rj@...renesas.com>, Wolfram Sang
 <wsa+renesas@...g-engineering.com>,  Uwe Kleine-König
 <u.kleine-koenig@...libre.com>, dmaengine@...r.kernel.org, 
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/4] dmaengine: sh: rz-dmac: Use
 devm_add_action_or_reset()

On Fr, 2025-09-05 at 17:22 +0200, Tommaso Merciai wrote:
> Hi Philipp,
> Thank you for your review!
> 
> On Fri, Sep 05, 2025 at 04:53:54PM +0200, Philipp Zabel wrote:
> > On Fr, 2025-09-05 at 16:44 +0200, Tommaso Merciai wrote:
> > > Slightly simplify rz_dmac_probe() by using devm_add_action_or_reset()
> > > for reset cleanup.
> > > 
> > > Signed-off-by: Tommaso Merciai <tommaso.merciai.xr@...renesas.com>
> > > ---
> > >  drivers/dma/sh/rz-dmac.c | 13 +++++++++++--
> > >  1 file changed, 11 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/drivers/dma/sh/rz-dmac.c b/drivers/dma/sh/rz-dmac.c
> > > index 0b526cc4d24be..0bc11a6038383 100644
> > > --- a/drivers/dma/sh/rz-dmac.c
> > > +++ b/drivers/dma/sh/rz-dmac.c
> > > @@ -905,6 +905,11 @@ static int rz_dmac_parse_of(struct device *dev, struct rz_dmac *dmac)
> > >  	return rz_dmac_parse_of_icu(dev, dmac);
> > >  }
> > >  
> > > +static void rz_dmac_reset_control_assert(void *data)
> > > +{
> > > +	reset_control_assert(data);
> > > +}
> > > +
> > >  static int rz_dmac_probe(struct platform_device *pdev)
> > >  {
> > >  	const char *irqname = "error";
> > > @@ -977,6 +982,12 @@ static int rz_dmac_probe(struct platform_device *pdev)
> > >  	if (ret)
> > >  		goto err_pm_runtime_put;
> > >  
> > > +	ret = devm_add_action_or_reset(&pdev->dev,
> > > +				       rz_dmac_reset_control_assert,
> > > +				       dmac->rstc);
> > > +	if (ret)
> > > +		goto err_pm_runtime_put;
> > > +
> > >  	for (i = 0; i < dmac->n_channels; i++) {
> > >  		ret = rz_dmac_chan_probe(dmac, &dmac->channels[i], i);
> > >  		if (ret < 0)
> > > @@ -1031,7 +1042,6 @@ static int rz_dmac_probe(struct platform_device *pdev)
> > >  				  channel->lmdesc.base_dma);
> > >  	}
> > >  
> > > -	reset_control_assert(dmac->rstc);
> > >  err_pm_runtime_put:
> > >  	pm_runtime_put(&pdev->dev);
> > >  
> > > @@ -1053,7 +1063,6 @@ static void rz_dmac_remove(struct platform_device *pdev)
> > >  				  channel->lmdesc.base,
> > >  				  channel->lmdesc.base_dma);
> > >  	}
> > > -	reset_control_assert(dmac->rstc);
> > 
> > This patch changes cleanup order by effectively moving the
> > reset_control_assert() after pm_runtime_put(). The commit message does
> > not explain that this is safe to do.
> 
> Agreed. Thanks.
> 
> > 
> > If this is ok, I'd move the reset_control_assert() up before
> > pm_runtime_enable/resume_and_get().
> 
> You mean having in the end the following calls:
> 
> ...
> 	dmac->rstc = devm_reset_control_array_get_optional_exclusive(&pdev->dev);
> 	if (IS_ERR(dmac->rstc))
> 		return dev_err_probe(&pdev->dev, PTR_ERR(dmac->rstc),
> 				     "failed to get resets\n");
> 
> 	ret = reset_control_deassert(dmac->rstc);
> 	if (ret)
> 		return dev_err_probe(&pdev->dev, ret,
> 				     "failed to deassert resets\n");
> 
> 	ret = devm_add_action_or_reset(&pdev->dev,
> 				       rz_dmac_reset_control_assert,
> 				       dmac->rstc);
> 	if (ret)
> 		return dev_err_probe(&pdev->dev, ret,
> 				     "failed to register reset cleanup action\n");
> 
> 	ret = devm_pm_runtime_enable(&pdev->dev);
> 	if (ret < 0)
> 		return dev_err_probe(&pdev->dev, ret,
> 				     "Failed to enable runtime PM\n");
> ...
> 
> Right?

Right.

regards
Philipp