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

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Date:	Thu, 31 Mar 2016 10:32:13 +0800
From:	Yingjoe Chen <yingjoe.chen@...iatek.com>
To:	Henry Chen <henryc.chen@...iatek.com>
CC:	John Crispin <blogic@...nwrt.org>,
	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 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