linux-kernel - Re: [PATCH] driver-core: platform: Avoid to return IRQ 0 in platform_get

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Date:   Wed, 6 Dec 2017 11:58:53 +0530
From:   Arvind Yadav <arvind.yadav.cs@...il.com>
To:     Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:     gregkh@...uxfoundation.org, davem@...emloft.net,
        linus.walleij@...aro.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] driver-core: platform: Avoid to return IRQ 0 in
 platform_get_irq()

Hi Dmitry,


On Tuesday 05 December 2017 11:50 PM, Dmitry Torokhov wrote:
> On Tue, Dec 05, 2017 at 11:41:52PM +0530, Arvind Yadav wrote:
>> Function platform_get_irq() can return 0. Which means NO_IRQ.
>> So this change will not allow to return 0.
>>
>> This change is help to use platform_get_irq() without this,
>>
>> 	val = platform_get_irq();
>> 	if (val <= 0)
>> 		ret = val ? val : -ENODEV;
>>
>> Signed-off-by: Arvind Yadav <arvind.yadav.cs@...il.com>
> You need to audit the drivers and make sure you are not breaking them
> with this. I believe at least i2c designware controller on certain
> boards has DEFINE_RES_IRQ(0) which will be broken by this patch.
Yes, you are right. Few driver is using  DEFINE_RES_IRQ(0).
Example:
drivers/mfd/intel-lpss.c
static const struct resource intel_lpss_dev_resources[] = {
         DEFINE_RES_MEM_NAMED(LPSS_DEV_OFFSET, LPSS_DEV_SIZE, "lpss_dev"),
         DEFINE_RES_MEM_NAMED(LPSS_PRIV_OFFSET, LPSS_PRIV_SIZE, 
"lpss_priv"),
         DEFINE_RES_IRQ(0),
};
There's a bunch of platforms in the kernel that still use IRQ0. They can 
suffer because
of this change. I should have mark this patch for testing.
>
>> ---
>>   drivers/base/platform.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/base/platform.c b/drivers/base/platform.c
>> index c203fb9..7b3079c 100644
>> --- a/drivers/base/platform.c
>> +++ b/drivers/base/platform.c
>> @@ -127,7 +127,7 @@ int platform_get_irq(struct platform_device *dev, unsigned int num)
>>   		irqd_set_trigger_type(irqd, r->flags & IORESOURCE_BITS);
>>   	}
>>   
>> -	return r ? r->start : -ENXIO;
>> +	return r && r->start ? r->start : -ENXIO;
>>   #endif
>>   }
>>   EXPORT_SYMBOL_GPL(platform_get_irq);
>> -- 
>> 2.7.4
>>
> Thanks.
>
Thanks,