linux-kernel - Re: Re: [PATCH] extcon: max77843: Clear IRQ bits state before request IRQ

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Date:	Mon, 08 Jun 2015 01:29:50 +0000 (GMT)
From:	MyungJoo Ham <myungjoo.ham@...sung.com>
To:	최찬우 <cw00.choi@...sung.com>
Cc:	김재원 <jaewon02.kim@...sung.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-samsung-soc@...r.kernel.org" 
	<linux-samsung-soc@...r.kernel.org>
Subject: Re: Re: [PATCH] extcon: max77843: Clear IRQ bits state before request
 IRQ

>   
>  On 06/05/2015 01:54 PM, MyungJoo Ham wrote:
> >>   
> >>  IRQ signal before driver probe is needless because driver sends
> >> current state after platform booting done.
> >> So, this patch clears MUIC IRQ bits before request IRQ.
> >>
> >> Signed-off-by: Jaewon Kim <jaewon02.kim@...sung.com>
> >> ---
> >>  drivers/extcon/extcon-max77843.c |    9 +++++++++
> >>  1 file changed, 9 insertions(+)
> > 
> > Q1. Is this because the pending bits are USELESS?
> > or because the pendeing bits incurs INCORRECT behaviors?
> 
> The max77843 datasheet includes following sentence:
> - "All bits are cleared after a read" about INT1/INT2/INT3 register.
> There are no problem about interrupt handling.
> 
> > 
> > Q2. Does clearing (by reading) INT1 do everything you need?
> > What about INT2 and INT3?
> 
> The MAXIM MAX77843 MUIC support the one more interrupts (e.g., ADC1K, VBVolt, ChgTyp ...).
> The each interrupt is included in the one register among INT1/2/3.
> 
> This patch clear the all interrupts of MAX77843 before requesting the interrupts.
> 
> > 
> > Q3. I presume that "driver sends current state after..." is
> > coming from the invokation of "queue_delayed_work()" at the end 
> > of the probe function. It appears that you are only serving
> > the pending status of "cable detection" with it while INT1
> > seems to have more functionalities. Does that delayed work
> > do everything that are pending, really?
> 
> When completed kernel booting, the delayed work of extcon-max77843.c driver
> use the MAX77843_MUIC_STATUSx register to detect the type of connected
> external connectors. So, there are no problme about clearing all bits of INT1/2/3 interrupt register.
> 
> If user-space platform don't finish the initialization of all user-process daemons
> and extcon driver send the uevent during only kernel booting, the uevent is not handled
> on user-space daemons.
> 
> Thanks,
> Chanwoo Choi

Ok. Looks Good. Thanks for the explanation.

Acked-by: MyungJoo Ham <myungjoo.ham@...sung.com>