RE: [PATCH v2 0/6] ARM: S5PV210: Add support S5PV210/S5PC110 CPUFREQ

From: Sangbeom Kim <sbkim73@samsung.com>
To: 'MyungJoo Ham' <myungjoo.ham@samsung.com>,
	'Kukjin Kim' <kgene.kim@samsung.com>
Cc: linux-samsung-soc@vger.kernel.org, ben-linux@fluff.org,
	linux-arm-kernel@lists.infradead.org
Subject: RE: [PATCH v2 0/6] ARM: S5PV210: Add support S5PV210/S5PC110 CPUFREQ
Date: Mon, 11 Oct 2010 17:04:17 +0900	[thread overview]
Message-ID: <003d01cb691a$eb71c8c0$c2555a40$@com> (raw)
In-Reply-To: <AANLkTikJL+94qODxkQGxzEPj0SCS3BA4=XQozJSHCpyR@mail.gmail.com>

On Monday, Oct 11, 2010 9:12 AM, MyungJoo Ham <myungjoo.ham@samsung.com> wrote:
> 
> Hello,
> 
> On Fri, Oct 8, 2010 at 6:52 PM, Kukjin Kim <kgene.kim@samsung.com> wrote:
> > Sangbeom Kim wrote:
> >>
> >> Hi all,
> >> I know that there is another S5PV210 CPUFREQ patch from Mr. Ham.
> >> But, That patchset seems to have unclear part.
> >>
> > http://lists.infradead.org/pipermail/linux-arm-kernel/2010-
> August/023626.htm
> >> l
> >> The part of 'CONFIG_PM' is unclear and still have PM support part.
> >> So, I think that this patch is more suitable for S5PV210/S5PC110
> CPUFREQ
> > in
> >> the mainline.
> >> because this patch implemented basic pm functionality and already
> tested
> > on
> >> smdkv210 board.
> >>
> > Hi,
> >
> > So...I'd like to merge this for this merge window.
> >
> > Mr. Ham, how do you think?
> > If any problems or opinions, please let me know.
> 
> 
> You can go ahead as long as this patch include features that the
> another addresses.
> 
> 
> Anyway, the part that is under "CONFIG_PM" is intended to block
> frequency changing while PM is doing something. For example, when the
> system enters a sleep, if CPUFREQ somehow enters "100MHz/0.95V" just
> before the sleep and wakes up, the voltage may stay at 0.95V (PMIC is
> not turned off during sleep) while the frequency is reset to 800MHz
> (by the bootloader), which requires, let's say, 1.1V. Such
> inconsistency may lead to system hang and we have observed such cases
> a few times. I intended to refuse any CPUFREQ requests at the
> /mach-s5pv210/cpufreq.c when PM seems to start.
> 

We knew already that issue, 
So we have a plan to implement with other solution. 
(using regulator suspend feature)

> It may seem that such feature is not needed if the voltage is not
> optimized, however, CPUFREQ is useless if the voltage stays at 1.2V
> and if the voltage changes properly according to the frequency, such
> feature is required anyway.

Currently, there is no max8698 regulator driver on mainline.
After submission that driver, we can add voltage scaling feature.

Both issues have dependency on regulator driver.

> 
> 
> ps. Anyway, such feature is also not included in my patch, either. :(
> (tried to included, but the code was excluded at the patch patching
> the patch.)
> 
> >
> > Thanks.
> >
> > Best regards,
> > Kgene.
> > --
> > Kukjin Kim <kgene.kim@samsung.com>, Senior Engineer,
> > SW Solution Development Team, Samsung Electronics Co., Ltd.
> >
> >> Thanks and regards,
> >> S.B. Kim
> >>
> >> > on Monday, September 20, 2010 3:05 PM, Sangbeom Kim
> >> <sbkim73@samsung.com>
> >> wrote:
> >> >
> >> > This patch adds CPUFREQ for S5PV210/S5PC110.
> >> >
> >> > Changes since v1:
> >> >
> >> > - Added MOUT_DMC0 and SCLK_DMC0 for checking the dmc0 clock in
> >> CPUFREQ
> >> > driver.
> >> > - Removed hardcoding of DRAM refresh counter.
> >> > - Added to calculate refresh counter function based on DRAM operation
> >> freq.
> >> >
> >> > [PATCH v2 1/6] ARM: S5PV210: Add DMC map_desc table for supporting
> DMC
> >> > access
> >> > [PATCH v2 2/6] ARM: S5PV210: Add struct clk_ops for clk_fout_apll
> >> > [PATCH v2 3/6] ARM: S5PV210: Add MOUT_DMC0 and SCLK_DMC0 clocks
> >> > [PATCH v2 4/6] ARM: S5PV210: Add Register definition for CMU
> >> > [PATCH v2 5/6] ARM: S5PV210: Add support CPUFREQ
> >> > [PATCH v2 6/6] ARM: S5PV210: Update Kconfig and Makefile for
> supporting
> >> > CPUFREQ driver
> >> > --
> >> > To unsubscribe from this list: send the line "unsubscribe linux-
> samsung-
> >> > soc" in
> >> > the body of a message to majordomo@vger.kernel.org
> >> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> >
> >
> > _______________________________________________
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> >
> 
> 
> 
> --
> MyungJoo Ham (함명주), Ph.D.
> Mobile Software Platform Lab,
> Digital Media and Communications (DMC) Business
> Samsung Electronics
> cell: 82-10-6714-2858
> 
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