[PATCH v2] i2c: cadence: Add an error handling for platform_get_irq()

[PATCH v2] i2c: cadence: Add an error handling for platform_get_irq()

[Dejin Zheng]

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")
Signed-off-by: Dejin Zheng <zhengdejin5@gmail.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;
-- 
2.25.0

Re: [PATCH v2] i2c: cadence: Add an error handling for platform_get_irq()

[Michal Simek]

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@gmail.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@xilinx.com>

Thanks,
Michal

Re: [PATCH v2] i2c: cadence: Add an error handling for platform_get_irq()

[Wolfram Sang]

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> 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;

I like this version better. Maybe we should simply move the
platform_get_irq() line to the devm_request_irq() call?


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Re: [PATCH v2] i2c: cadence: Add an error handling for platform_get_irq()

[Michal Simek]

On 22. 05. 20 17:14, Wolfram Sang wrote:
> 
>> 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;
> 
> I like this version better. Maybe we should simply move the
> platform_get_irq() line to the devm_request_irq() call?

You know about
devm_platform_get_and_ioremap_resource()
usage.
 Maybe that's the way to go. Because as of today there is no way to pass
position of irq resource.

But I expect it will come in near future.

Thanks,
Michal

Re: [PATCH v2] i2c: cadence: Add an error handling for platform_get_irq()

[Wolfram Sang]

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> You know about
> devm_platform_get_and_ioremap_resource()
> usage.
>  Maybe that's the way to go. Because as of today there is no way to pass
> position of irq resource.
> 
> But I expect it will come in near future.

Has been tried, has been nacked:

http://patchwork.ozlabs.org/project/linux-i2c/patch/20200518155304.28639-3-zhengdejin5@gmail.com/


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Re: [PATCH v2] i2c: cadence: Add an error handling for platform_get_irq()

[Dejin Zheng]

On Fri, May 22, 2020 at 10:19:56PM +0200, Wolfram Sang wrote:
> 
> > You know about
> > devm_platform_get_and_ioremap_resource()
> > usage.
> >  Maybe that's the way to go. Because as of today there is no way to pass
> > position of irq resource.
> > 
> > But I expect it will come in near future.
> 
> Has been tried, has been nacked:
> 
> http://patchwork.ozlabs.org/project/linux-i2c/patch/20200518155304.28639-3-zhengdejin5@gmail.com/
> 
Wolfram and Michal, Thanks very much for your comments, I will resend
devm_platform_request_irq() again. 

BR,
Dejin

Re: [PATCH v2] i2c: cadence: Add an error handling for platform_get_irq()

[Dejin Zheng]

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@gmail.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@xilinx.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