linux-kernel - Re: [PATCH 2/3] gpio: pxa: Fix return value of pxa_gpio

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Date:   Sat, 23 May 2020 11:24:46 +0800
From:   Tiezhu Yang <yangtiezhu@...ngson.cn>
To:     Robert Jarzmik <robert.jarzmik@...e.fr>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Ray Jui <rjui@...adcom.com>,
        bcm-kernel-feedback-list@...adcom.com, linux-gpio@...r.kernel.org,
        linux-kernel@...r.kernel.org, Xuefeng Li <lixuefeng@...ngson.cn>
Subject: Re: [PATCH 2/3] gpio: pxa: Fix return value of pxa_gpio_probe()

On 05/23/2020 03:07 AM, Robert Jarzmik wrote:
> Tiezhu Yang <yangtiezhu@...ngson.cn> writes:
>
>> When call function devm_platform_ioremap_resource(), we should use IS_ERR()
>> to check the return value and return PTR_ERR() if failed.
>>
>> Fixes: 542c25b7a209 ("drivers: gpio: pxa: use devm_platform_ioremap_resource()")
>> Signed-off-by: Tiezhu Yang <yangtiezhu@...ngson.cn>
>> ---
>>   drivers/gpio/gpio-pxa.c | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpio/gpio-pxa.c b/drivers/gpio/gpio-pxa.c
>> index 1361270..0cb6600 100644
>> --- a/drivers/gpio/gpio-pxa.c
>> +++ b/drivers/gpio/gpio-pxa.c
>> @@ -660,8 +660,8 @@ static int pxa_gpio_probe(struct platform_device *pdev)
>>   	pchip->irq1 = irq1;
>>   
>>   	gpio_reg_base = devm_platform_ioremap_resource(pdev, 0);
>> -	if (!gpio_reg_base)
>> -		return -EINVAL;
>> +	if (IS_ERR(gpio_reg_base))
>> +		return PTR_ERR(gpio_reg_base);
> As far as I know, devm_platform_ioremap_resource() could return NULL which is
> not handled by this test (unless __devm_ioremap() semantics changed since I had
> a look).

Hi Robert,

In the function __devm_ioremap_resource(), if __devm_ioremap returns NULL,
it will return IOMEM_ERR_PTR(-ENOMEM).

devm_platform_ioremap_resource()
         devm_ioremap_resource()
                 __devm_ioremap_resource()
                        __devm_ioremap()

static void __iomem *
__devm_ioremap_resource(struct device *dev, const struct resource *res,
             enum devm_ioremap_type type)
{
...
     dest_ptr = __devm_ioremap(dev, res->start, size, type);
     if (!dest_ptr) {
         dev_err(dev, "ioremap failed for resource %pR\n", res);
         devm_release_mem_region(dev, res->start, size);
         dest_ptr = IOMEM_ERR_PTR(-ENOMEM);
     }

     return dest_ptr;
}

And also, we can see the comment of devm_ioremap_resource():

Usage example:

         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
         base = devm_ioremap_resource(&pdev->dev, res);
         if (IS_ERR(base))
                 return PTR_ERR(base);

>
> Therefore, this patch is incorrect, or rather incomplete.

So I think this patch is correct, do I miss something?

Thanks,
Tiezhu Yang

>
> Cheers.
>