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Message-ID: <20131127033555.GY9468@ld-irv-0074.broadcom.com>
Date: Tue, 26 Nov 2013 19:35:55 -0800
From: Brian Norris <computersforpeace@...il.com>
To: Jingoo Han <jg1.han@...sung.com>
Cc: 'Wei Yongjun' <weiyj.lk@...il.com>,
'David Woodhouse' <dwmw2@...radead.org>,
'Bill Pemberton' <wfp5p@...ginia.edu>,
'Artem Bityutskiy' <artem.bityutskiy@...ux.intel.com>,
'Wei Yongjun' <yongjun_wei@...ndmicro.com.cn>,
linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] MIPS: Alchemy: add missing platform_set_drvdata() in
au1550nd_probe()
Hi Jingoo,
On Wed, Nov 27, 2013 at 09:14:18AM +0900, Jingoo Han wrote:
> On Wednesday, November 27, 2013 8:50 AM, Brian Norris wrote:
> > On Mon, Nov 11, 2013 at 02:18:29PM +0800, Wei Yongjun wrote:
> > > From: Wei Yongjun <yongjun_wei@...ndmicro.com.cn>
> > >
> > > Add missing platform_set_drvdata() in au1550nd_probe(), otherwise
> > > calling platform_get_drvdata() in remove returns NULL.
> >
> > An alternative solution: just allocate ctx with devm_kzalloc().Then you
> > don't have to kfree() it at all.
>
> Even if devm_kzalloc() is used, missing platform_set_drvdata() will
> be still necessary.
>
> static int au1550nd_remove(struct platform_device *pdev)
> {
> struct au1550nd_ctx *ctx = platform_get_drvdata(pdev);
> .....
>
> nand_release(&ctx->info);
>
> 'ctx' is still used. Also, in order to use 'ctx',
> platform_get_drvdata(pdev) should be called.
Ah, I overlooked that. Thanks. In that case, you still have to do
something like this patch, and devm_kzalloc() can be left for another
day (or not done at all).
> >
> > I don't mind one solution over the other too much. Let me know which
> > you'd prefer.
> >
> > > Signed-off-by: Wei Yongjun <yongjun_wei@...ndmicro.com.cn>
> > > ---
> > > drivers/mtd/nand/au1550nd.c | 2 ++
> > > 1 file changed, 2 insertions(+)
> > >
> > > diff --git a/drivers/mtd/nand/au1550nd.c b/drivers/mtd/nand/au1550nd.c
> > > index ae8dd7c..909b673 100644
> > > --- a/drivers/mtd/nand/au1550nd.c
> > > +++ b/drivers/mtd/nand/au1550nd.c
> > > @@ -480,6 +480,8 @@ static int au1550nd_probe(struct platform_device *pdev)
> > >
> > > mtd_device_register(&ctx->info, pd->parts, pd->num_parts);
> > >
> > > + platform_set_drvdata(pdev, ctx);
> > > +
> >
> > Personally, I'd choose to call platform_set_drvdata() earlier in the
> > probe routine (e.g., immediately after its allocation), in case we end
> > up calling platform_get_drvdata() from some sub-routine in the future.
>
> Do you mean the following?
> But, most drivers calls platform_set_drvdata() later in the probe routine.
I wouldn't say "most." An unscientific survey seemed to show some
variation, with no clear pattern.
> static int au1550nd_probe(struct platform_device *pdev)
> {
> struct au1550nd_platdata *pd;
> struct au1550nd_ctx *ctx;
> struct nand_chip *this;
> struct resource *r;
> int ret, cs;
>
> pd = dev_get_platdata(&pdev->dev);
> if (!pd) {
> dev_err(&pdev->dev, "missing platform data\n");
> return -ENODEV;
> }
>
> ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
> if (!ctx) {
> dev_err(&pdev->dev, "no memory for NAND context\n");
> return -ENOMEM;
> }
>
> + platform_set_drvdata(pdev, ctx);
> +
Yes, that looks better to me.
Brian
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