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

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Date:   Tue, 17 Sep 2019 14:06:46 +0000
From:   Aurabindo Jayamohanan <mail@...abindo.in>
To:     Paul Walmsley <paul.walmsley@...ive.com>
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()

Hi Paul,

‐‐‐‐‐‐‐ 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, here is a patch:
____

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

calls to devm_ioremap_resource() preceeded by platform_get_resource()
may be replaced by devm_platform_ioremap_resource().

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