linux-kernel - Re: [PATCH v2] i2c: cadence: Add an error handling for platform_get

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Date:   Sat, 23 May 2020 23:26:10 +0800
From:   Dejin Zheng <zhengdejin5@...il.com>
To:     Michal Simek <michal.simek@...inx.com>
Cc:     wsa@...-dreams.de, harinik@...inx.com, soren.brinkmann@...inx.com,
        linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] i2c: cadence: Add an error handling for
 platform_get_irq()

On Fri, May 22, 2020 at 01:24:57PM +0200, Michal Simek wrote:
> On 20. 05. 20 16:48, Dejin Zheng wrote:
> > The driver initialization should be end immediately after found
> > the platform_get_irq() function return an error.
> > 
> > Fixes: df8eb5691c48d3b0 ("i2c: Add driver for Cadence I2C controller")
> 
> I wouldn't really consider this as bug. Driver is likely not failing
> when irq is not defined. It should just fail later on when
> devm_request_irq is called.
> Or is there any other issue with it?
> 
> > Signed-off-by: Dejin Zheng <zhengdejin5@...il.com>
> > ---
> > v1 -> v2:
> > 	- add Fixes tag.
> > 
> >  drivers/i2c/busses/i2c-cadence.c | 2 ++
> >  1 file changed, 2 insertions(+)
> > 
> > diff --git a/drivers/i2c/busses/i2c-cadence.c b/drivers/i2c/busses/i2c-cadence.c
> > index 89d58f7d2a25..0e8debe32cea 100644
> > --- a/drivers/i2c/busses/i2c-cadence.c
> > +++ b/drivers/i2c/busses/i2c-cadence.c
> > @@ -912,6 +912,8 @@ static int cdns_i2c_probe(struct platform_device *pdev)
> >  		return PTR_ERR(id->membase);
> >  
> >  	id->irq = platform_get_irq(pdev, 0);
> > +	if (id->irq < 0)
> > +		return id->irq;
> >  
> >  	id->adap.owner = THIS_MODULE;
> >  	id->adap.dev.of_node = pdev->dev.of_node;
> > 
> 
> The change is valid but the question is if make sense to do it in this
> way. Some drivers are using devm_request_irq to do do job.
> 
> For example:
>  	id->irq = platform_get_irq(pdev, 0);
>         ret = devm_request_irq(&pdev->dev, id->irq, cdns_i2c_isr, 0,
>                                   DRIVER_NAME, id);
>         if (ret)
> 		return ret;
> 
> But I am also fine with solution above where you fail in quickest way.
> 
> Without that Fixed tag
> Acked-by: Michal Simek <michal.simek@...inx.com>
>

Michal, Thanks very much for review my patch, As you said, maybe the
better way is provide a function like the devm_platform_get_and_ioremap_resource().
So I resend a patch of I gave up before, It's here now:
https://patchwork.ozlabs.org/project/linux-i2c/patch/20200523145157.16257-3-zhengdejin5@gmail.com/

Abandon this patch and Thanks again!

BR,
Dejin

> Thanks,
> Michal