linux-kernel - Re: [PATCH v2] can: Fix bug in suspend/resume

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Date:	Fri, 14 Nov 2014 09:54:37 +0100
From:	Marc Kleine-Budde <mkl@...gutronix.de>
To:	Kedareswara rao Appana <appana.durga.rao@...inx.com>,
	wg@...ndegger.com, michal.simek@...inx.com,
	soren.brinkmann@...inx.com, grant.likely@...aro.org,
	robh+dt@...nel.org
CC:	linux-can@...r.kernel.org, netdev@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	devicetree@...r.kernel.org,
	Kedareswara rao Appana <appanad@...inx.com>
Subject: Re: [PATCH v2] can: Fix bug in suspend/resume

On 11/14/2014 09:16 AM, Kedareswara rao Appana wrote:
> The drvdata in the suspend/resume is of type struct net_device,
> not the platform device.Enable the clocks in the suspend before
> accessing the registers of the CAN.
> 
> Signed-off-by: Kedareswara rao Appana <appanad@...inx.com>
> ---
> Changes for v2:
>   - Removed the struct platform_device* from suspend/resume
>     as suggest by Lothar.
>   - The clocks are getting disabled and un prepared at the end of the probe. 
>     In the suspend the driver is doing a register write.In order
>     To do that register write we have to again enable and prepare the clocks.

Please look the at suspend/resume code and count the
clock_enable/disable manually. After a suspend/resume cycle, you have
enabled the clock twice, but disabled it once.

I think you have to abstract the clock handling behind runtime PM. I
haven't done this myself yet, but the strong feeling that this is a
possible solution to your problem. These links might help:

http://lwn.net/Articles/505683/
http://www.slideshare.net/linaroorg/runtime-pm
http://www.slideshare.net/linaroorg/lca14-407-deployingruntimepmonarmsocs
http://www.slideshare.net/SamsungOSG/shuah-khan-lpcpmops

Marc
-- 
Pengutronix e.K.                  | Marc Kleine-Budde           |
Industrial Linux Solutions        | Phone: +49-231-2826-924     |
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