linux-kernel - Re: [PATCH v4 1/2] ARM: socfpga: support suspend to ram

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Message-ID: <alpine.DEB.2.02.1505281522260.31038@linuxheads99>
Date:	Thu, 28 May 2015 15:23:16 -0500
From:	atull <atull@...nsource.altera.com>
To:	Dinh Nguyen <dinguyen@...nsource.altera.com>
CC:	Rob Herring <robh+dt@...nel.org>, Pavel Machek <pavel@...x.de>,
	"Arnd Bergmann" <arnd@...db.de>,
	Steffen Trumtrar <s.trumtrar@...gutronix.de>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	"Ian Campbell" <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	<devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	Russell King <linux@....linux.org.uk>,
	<linux-arm-kernel@...ts.infradead.org>,
	"Delicious Quinoq" <delicious.quinoa@...il.com>
Subject: Re: [PATCH v4 1/2] ARM: socfpga: support suspend to ram

On Thu, 28 May 2015, Dinh Nguyen wrote:

> On 05/27/2015 03:25 PM, atull wrote:
> > On Tue, 26 May 2015, Dinh Nguyen wrote:
> > 
> >> Hi Alan,
> >>
> >> On 5/22/15 1:02 PM, Alan Tull wrote:
> >>> 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
> >>>
> >>> Suspend-to-RAM and EDAC support are mutually exclusive on SOCFPGA
> >>> platforms.  CONFIG_SOCFPGA_SUSPEND enables suspend-to-RAM and
> >>> prevents selecting CONFIG_EDAC_ALTERA_MC.
> >>>
> >>> How to suspend to ram:
> >>>  $ echo enabled > \
> >>> /sys/devices/soc/ffc02000.serial0/tty/ttyS0/power/wakeup
> >>>
> >>>  $ echo -n mem > /sys/power/state
> >>>
> >>> Signed-off-by: Alan Tull <atull@...nsource.altera.com>
> >>> Cc: Pavel Machek <pavel@...x.de>
> >>> Cc: Arnd Bergmann <arnd@...db.de>
> >>> Cc: Dinh Nguyen <dinguyen@...nsource.altera.com>
> >>> Cc: Steffen Trumtrar <s.trumtrar@...gutronix.de>
> >>> ---
> >>> v2: use Generic on-chip SRAM driver to allocate ocram
> >>>     rm fncpy_align since generic allocator handles alignment
> >>>     check __arm_ioremap_exec return code
> >>>     check for NULL pointers
> >>>     add a comment regarding sdram controller configuration
> >>> v3: fix renamed #define
> >>>     propagate socfpga_setup_ocram_self_refresh error code
> >>> v4: Kconfig: don't need to select GENERIC_ALLOCATER
> >>>     add CONFIG_SOCFPGA_SUSPEND
> >>>     make s2r and EDAC support mutually exclusive
> >>>     socfpga.c: add sdr_ctl_base_addr
> >>>     return error if ocram not available in device tree
> >>>     update copyright years
> >>> ---
> >>
> >> <snip>
> >>
> >>> +
> >>> +static int socfpga_pm_suspend(unsigned long arg)
> >>> +{
> >>> +	u32 ret;
> >>> +
> >>> +	if (!sdr_ctl_base_addr || !socfpga_scu_base_addr)
> >>> +		return -EFAULT;
> >>> +
> >>> +	ret = socfpga_sdram_self_refresh_in_ocram(
> >>> +		(u32)sdr_ctl_base_addr, (u32)socfpga_scu_base_addr);
> >>> +
> >>
> >> I had a patch that removed socfpga_scu_base_addr from being a global and
> >> just a local variable in:
> >>
> >> f6e14376fb20 ARM: socfpga: use of_iomap to map the SCU
> >>
> >> This patch will be in v4.2 and is currently in arm-soc/next or
> >> at my fork: kernel/git/dinguyen/linux.git socfpga_for_next_arria10
> >>
> >> So you will either need to make socfpga_scu_base_addr global again, or
> >> you can use the asm instruction to get the SCU base addr.
> >>
> >> Sorry about that..
> >>
> >> Dinh
> >>
> > 
> > I can't make socfpga_scu_base_addr a global from platsmp.c since that file
> > may or may not be compiled in.
> 
> Ah, okay..
> > 
> > That leaves me with the option of adding the code that was removed from
> > socfpga.c back where it was or taking that same code moving it to pm.c
> > 
> 
> I think you only need the scu base address in
> socfpga_sdram_self_refresh(), so you can probably just use the single
> line assembly code to get it there.
> 
> Dinh
> 

I realized that I don't need to touch the scu self refresh bit at all 
here.  It's handled in scu_enable().

Alan

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