Date: Fri, 14 Nov 2014 07:05:14 -0800
From: =?utf-8?B?U8O2cmVu?= Brinkmann <soren.brinkmann@xilinx.com>
To: Marc Kleine-Budde <mkl@pengutronix.de>
CC: Kedareswara rao Appana <appana.durga.rao@xilinx.com>, <wg@grandegger.com>,
        <michal.simek@xilinx.com>, <grant.likely@linaro.org>,
        <robh+dt@kernel.org>, <linux-can@vger.kernel.org>,
        <netdev@vger.kernel.org>, <linux-arm-kernel@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>, <devicetree@vger.kernel.org>,
        Kedareswara rao Appana <appanad@xilinx.com>
Subject: Re: [PATCH v2] can: Fix bug in suspend/resume
References: <e7070431858e49e29cd03d76fd7a66c3@BN1AFFO11FD055.protection.gbl>
 <5465C34D.4030805@pengutronix.de>
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On Fri, 2014-11-14 at 09:54AM +0100, Marc Kleine-Budde wrote:
> 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@xilinx.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:

I agree, the clock handling looks weird. Also the clk_disable calls in
xcan_get_berr_counter() look suspicious to me, but I might be wrong.
I think you can take a look at gpio-zynq for an example for runtime_pm
usage. I think the usage model in that driver is similar to here.

	Thanks,
	Sören
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