linux-kernel - Re: [PATCH] spi: sifive: check return value for platform_get

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Date:   Tue, 17 Sep 2019 07:11:16 -0700 (PDT)
From:   Paul Walmsley <paul.walmsley@...ive.com>
To:     Aurabindo Jayamohanan <mail@...abindo.in>
cc:     Baolin Wang <baolin.wang@...aro.org>,
        Mark Brown <broonie@...nel.org>,
        "palmer@...ive.com" <palmer@...ive.com>,
        linux-spi <linux-spi@...r.kernel.org>,
        "linux-riscv@...ts.infradead.org" <linux-riscv@...ts.infradead.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] spi: sifive: check return value for
 platform_get_resource()

Aurobindo, 

On Tue, 17 Sep 2019, Aurabindo Jayamohanan wrote:

> ‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
> On Tuesday, September 17, 2019 5:45 PM, Paul Walmsley <paul.walmsley@...ive.com> wrote:
> 
> > On Tue, 17 Sep 2019, Baolin Wang wrote:
> >
> > > On Tue, 17 Sep 2019 at 17:12, Aurabindo Jayamohanan mail@...abindo.in wrote:
> > >
> > > > platform_get_resource() may return NULL. If it is so, return -ENXIO
> > > >
> > > > Signed-off-by: Aurabindo Jayamohanan mail@...abindo.in
> > > >
> > > > -------------------------------------------------------
> > > >
> > > > drivers/spi/spi-sifive.c | 6 ++++++
> > > > 1 file changed, 6 insertions(+)
> > > > diff --git a/drivers/spi/spi-sifive.c b/drivers/spi/spi-sifive.c
> > > > index 93ec2c6cdbfd..67485067a694 100644
> > > > --- a/drivers/spi/spi-sifive.c
> > > > +++ b/drivers/spi/spi-sifive.c
> > > > @@ -308,6 +308,12 @@ static int sifive_spi_probe(struct platform_device *pdev)
> > > > platform_set_drvdata(pdev, master);
> > > >
> > > >         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > > >
> > > >
> > > > -         if (!res) {
> > > >
> > > >
> > > > -                 dev_err(&pdev->dev, "no IOMEM resource found\\n");
> > > >
> > > >
> > > > -                 ret = -ENXIO;
> > > >
> > > >
> > > > -                 goto put_master;
> > > >
> > > >
> > > > -         }
> > > >
> > > >
> > >
> > > Seems unnecessary, the devm_ioremap_resource() already validated if
> > > the resource is available.
> >
> > Just doublechecked lib/devres.c and I agree with you.
> >
> > Aurobindo, is this a patch for a real problem that you've encountered?
> >
> > -   Paul
> 
> Geert is right. I was just breezing through the source and found it odd since
> I noticed other instances checking for return value. Apparently none of those
> use the managed api.
> 
> If you didnt already do Geert's suggestion,

Mark Brown is the maintainer, so he'd be the one to apply anything 
touching these drivers.

> here is a patch:

Could you please send this as a separate E-mail?

> ____
> 
> spi: sifive: use device managed api to get plaform resource

"platform resource"

> 
> calls to devm_ioremap_resource() preceeded by platform_get_resource()

"Calls"

"preceded"

> may be replaced by devm_platform_ioremap_resource().

Please explain why.  In this case "removing boilerplate from the code" 
seems like a reasonable explanation.

> 
> Signed-off-by: Aurabindo Jayamohanan <mail@...abindo.in>
> ---
>  drivers/spi/spi-sifive.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/drivers/spi/spi-sifive.c b/drivers/spi/spi-sifive.c
> index 93ec2c6cdbfd..c0925aa98aad 100644
> --- a/drivers/spi/spi-sifive.c
> +++ b/drivers/spi/spi-sifive.c
> @@ -292,7 +292,6 @@ sifive_spi_transfer_one(struct spi_master *master, struct spi_device *device,
>  static int sifive_spi_probe(struct platform_device *pdev)
>  {
>  	struct sifive_spi *spi;
> -	struct resource *res;
>  	int ret, irq, num_cs;
>  	u32 cs_bits, max_bits_per_word;
>  	struct spi_master *master;
> @@ -307,8 +306,7 @@ static int sifive_spi_probe(struct platform_device *pdev)
>  	init_completion(&spi->done);
>  	platform_set_drvdata(pdev, master);
> 
> -	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> -	spi->regs = devm_ioremap_resource(&pdev->dev, res);
> +	spi->regs = devm_platform_ioremap_resource(pdev, 0);
>  	if (IS_ERR(spi->regs)) {
>  		ret = PTR_ERR(spi->regs);
>  		goto put_master;
> --
> 2.23.0
> 


- Paul