linux-kernel - Re: [PATCH 2/2] socfpga: support suspend to ram

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Message-ID: <20140925082506.GC26991@pengutronix.de>
Date:	Thu, 25 Sep 2014 10:25:06 +0200
From:	Steffen Trumtrar <s.trumtrar@...gutronix.de>
To:	atull@...nsource.altera.com
Cc:	dinguyen@...nsource.altera.com, linux@....linux.org.uk,
	yvanderv@...nsource.altera.com, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, delicious.quinoa@...il.com
Subject: Re: [PATCH 2/2] socfpga: support suspend to ram

Hi!

On Wed, Sep 24, 2014 at 03:27:29PM -0500, atull@...nsource.altera.com wrote:
> From: Alan Tull <atull@...nsource.altera.com>
> 
> Add code that requests that the sdr controller go into
> self-refresh mode.  This code is run from ocram.
> 
> This patch assumes that u-boot has already configured sdr:
>   sdr.ctrlcfg.lowpwreq.selfrfshmask = 3
>   sdr.ctrlcfg.lowpwrtiming.clkdisablecycles = 8
>   sdr.ctrlcfg.dramtiming4.selfrfshexit = 512
> 
> How to suspend to ram:
>  $ echo enabled > \
> /sys/devices/soc/ffc02000.serial0/tty/ttyS0/power/wakeup
> 
>  $ echo -n mem > /sys/power/state
> 

(...)

Never looked into that, so maybe a stupid question:
What happens if the bootloader (u-boot or other) didn't configure the sdr?
Will it "just" not wake up again?

Regards,
Steffen

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