linux-kernel - Re: [PATCH] mfd: mt6397: irq domain should initialize before mfd_add

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Date:	Thu, 31 Mar 2016 11:08:32 +0200
From:	John Crispin <blogic@...nwrt.org>
To:	Yingjoe Chen <yingjoe.chen@...iatek.com>,
	Henry Chen <henryc.chen@...iatek.com>
Cc:	Sascha Hauer <s.hauer@...gutronix.de>,
	linux-kernel@...r.kernel.org, Flora Fu <flora.fu@...iatek.com>,
	linux-mediatek@...ts.infradead.org,
	Matthias Brugger <matthias.bgg@...il.com>,
	Lee Jones <lee.jones@...aro.org>,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] mfd: mt6397: irq domain should initialize before
 mfd_add_devices()



On 31/03/2016 04:32, Yingjoe Chen wrote:
> On Thu, 2016-03-31 at 09:40 +0800, Henry Chen wrote:
>> On Wed, 2016-03-30 at 11:18 +0200, John Crispin wrote:
>>> Hi,
>>>
>>> small nitpick inline
>>>
>>> On 30/03/2016 09:25, Henry Chen wrote:
>>>> Some sub driver like RTC module need irq domain from parent to create
>>>> irq mapping when driver initialize. so move mt6397_irq_init() before
>>>> mfd_add_devices().
>>>>
>>>> Signed-off-by: Henry Chen <henryc.chen@...iatek.com>
>>>> ---
>>>> This patch fixed the below warning based on "Linux kernel v4.6-rc1"
>>>> WARNING: CPU: 1 PID: 132 at kernel/mediatek/kernel/irq/irqdomain.c:471
>>>> irq_create_mapping+0xc4/0xd0
>>>> ---
>>>>  drivers/mfd/mt6397-core.c | 37 ++++++++++++++++++++++---------------
>>>>  1 file changed, 22 insertions(+), 15 deletions(-)
>>>>
>>>> diff --git a/drivers/mfd/mt6397-core.c b/drivers/mfd/mt6397-core.c
>>>> index 8e8d932..a879223 100644
>>>> --- a/drivers/mfd/mt6397-core.c
>>>> +++ b/drivers/mfd/mt6397-core.c
>>>> @@ -270,22 +270,36 @@ static int mt6397_probe(struct platform_device *pdev)
>>>>  		goto fail_irq;
>>>>  	}
>>>>  
>>>> +	pmic->irq = platform_get_irq(pdev, 0);
>>>> +
>>>>  	switch (id & 0xff) {
>>>>  	case MT6323_CID_CODE:
>>>> -		pmic->int_con[0] = MT6323_INT_CON0;
>>>> -		pmic->int_con[1] = MT6323_INT_CON1;
>>>> -		pmic->int_status[0] = MT6323_INT_STATUS0;
>>>> -		pmic->int_status[1] = MT6323_INT_STATUS1;
>>>> +		if (pmic->irq > 0) {
>>>
>>> should this not be
>>>
>>> 		if (pmic->irq >= 0) {
>>>
>>> i think the code before your patch was wrong as linux irqs start with 0.
>>>
>>> 	John
>> Hi John,
>>
>> Thanks, I will modify this.
> 
> Linux irq start from 1, 0 is invalid. I can't find the document saying
> this now, but you could see this from irq_create_mapping() in
> kernel/irq/irqdomain.c
> 
> I think the code should have check return from platform_get_irq and
> handle -EPROBE_DEFER, but maybe it should be another patch?
> 
> BTW, in this function, it is possible that pmic->irq_domain will be NULL
> in fail_irq error handling. We should check before calling
> irq_domain_remove.
> 
> Joe.C
> 

Hi,

looking at
http://lxr.free-electrons.com/source/drivers/base/platform.c#L87 there
is a check in line #100 ret >= 0

checking the return value of pmic->irq = platform_get_irq(pdev, 0);
should follow the same pattern i think .. unless i have a thinko and am
reading the code wrong.

	John