linux-kernel - Re: [PATCH v3 02/14] mfd: max77686: Allow the max77686 rtc to wakeup the system

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Message-ID: <53AB10C0.9050803@collabora.co.uk>
Date:	Wed, 25 Jun 2014 20:11:12 +0200
From:	Javier Martinez Canillas <javier.martinez@...labora.co.uk>
To:	Doug Anderson <dianders@...omium.org>
CC:	Krzysztof Kozlowski <k.kozlowski@...sung.com>,
	Lee Jones <lee.jones@...aro.org>,
	Samuel Ortiz <sameo@...ux.intel.com>,
	Mark Brown <broonie@...nel.org>,
	Mike Turquette <mturquette@...aro.org>,
	Liam Girdwood <lgirdwood@...il.com>,
	Alessandro Zummo <a.zummo@...ertech.it>,
	Kukjin Kim <kgene.kim@...sung.com>,
	Olof Johansson <olof@...om.net>,
	Sjoerd Simons <sjoerd.simons@...labora.co.uk>,
	Daniel Stone <daniels@...labora.com>,
	Tomeu Vizoso <tomeu.vizoso@...labora.com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	linux-samsung-soc <linux-samsung-soc@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 02/14] mfd: max77686: Allow the max77686 rtc to wakeup
 the system

On 06/25/2014 07:24 PM, Doug Anderson wrote:
> Hi,
> 
> On Wed, Jun 25, 2014 at 3:29 AM, Javier Martinez Canillas
> <javier.martinez@...labora.co.uk> wrote:
>> Yes, the original Chrome OS 3.8 max77xxx also called the irq worker thread to
>> ack the interrupt.
>>
>> So the real problem is that an interrupt occurs before the I2C bus controller is
>> resumed and so the interrupt handler is not able to access the registers over I2C.
>>
>> Doug posted the following patches [0,1] that AFAIU solves the issue by making
>> I2C controllers to be resumed in the noirq time to ensure that drivers will be
>> able to use the I2C bus to handler their wakeup.
> 
> Yup, that's the solution as far as I know.  I know that in ChromeOS we
> still have the extra call to the worker thread (despite the controller
> waking up early), but that might be related to some other problem?
> 
> I was able to successfully suspend/resume multiple times once I woke
> the i2c controller up earlier.
> 
> If you feel like adding Reviewed-by / Tested-by to my i2c patch then
> feel free!  ;)
> 
> 

Done :)

>> In fact, Doug's original patch had this as a part of the commit message:
>>
>> NOTE: due to wakeup ordering problems this patch alone doesn't work so
>> well on exynos5250-snow.  You also need something that brings the i2c
>> bus up before the max77686 wakeup runs.
>>
>> I removed that note since I (probably wrong) thought that he didn't mean it to
>> be part of the commit message but just was side information.
> 
> I probably would have left that in the patch, but I'm not objecting to
> you taking it out.  :)
> 

Yes, I should had left that as well. I'll send a v4 shortly and will include the
note again.

Best regards,
Javier
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