linux-kernel - Re: [PATCH 2/4] soc: Mediatek: Add SCPSYS power domain driver

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Message-ID: <20150527062430.GN6325@pengutronix.de>
Date:	Wed, 27 May 2015 08:24:30 +0200
From:	Sascha Hauer <s.hauer@...gutronix.de>
To:	Kevin Hilman <khilman@...nel.org>
Cc:	linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-mediatek@...ts.infradead.org,
	kernel@...gutronix.de, Matthias Brugger <matthias.bgg@...il.com>
Subject: Re: [PATCH 2/4] soc: Mediatek: Add SCPSYS power domain driver

On Tue, May 26, 2015 at 03:35:14PM -0700, Kevin Hilman wrote:
> Sascha Hauer <s.hauer@...gutronix.de> writes:
> 
> > This adds a power domain driver for the Mediatek SCPSYS unit.
> >
> > The System Control Processor System (SCPSYS) has several power
> > management related tasks in the system. The tasks include thermal
> > measurement, dynamic voltage frequency scaling (DVFS), interrupt
> > filter and lowlevel sleep control. The System Power Manager (SPM)
> > inside the SCPSYS is for the MTCMOS power domain control.
> >
> > For now this driver only adds power domain support, the more
> > advanced features are not yet supported. The driver implements
> > the generic PM domain device tree bindings, the first user will
> > most likely be the Mediatek AFE audio driver.
> >
> > Signed-off-by: Sascha Hauer <s.hauer@...gutronix.de>
> > ---
> >  drivers/soc/mediatek/Kconfig             |   6 +
> >  drivers/soc/mediatek/Makefile            |   1 +
> >  drivers/soc/mediatek/mtk-scpsys.c        | 345 +++++++++++++++++++++++++++++++
> >  include/dt-bindings/power/mt8173-power.h |  15 ++
> >  4 files changed, 367 insertions(+)
> >  create mode 100644 drivers/soc/mediatek/mtk-scpsys.c
> >  create mode 100644 include/dt-bindings/power/mt8173-power.h
> >
> > diff --git a/drivers/soc/mediatek/Kconfig b/drivers/soc/mediatek/Kconfig
> > index bcdb22d..1d34819 100644
> > --- a/drivers/soc/mediatek/Kconfig
> > +++ b/drivers/soc/mediatek/Kconfig
> > @@ -9,3 +9,9 @@ config MTK_PMIC_WRAP
> >  	  Say yes here to add support for MediaTek PMIC Wrapper found
> >  	  on different MediaTek SoCs. The PMIC wrapper is a proprietary
> >  	  hardware to connect the PMIC.
> > +
> > +config MTK_SCPSYS
> > +	tristate "MediaTek SCPSYS Support"
> 
> depends on ARCH_MEDIATEK ?

You are reviewing v2 of this series. This is already fixed in v3 sent
out last wednesday.

> > +	for (i = 0; i < NUM_DOMAINS; i++) {
> > +		struct scp_domain *scpd = &scp->domains[i];
> > +		struct generic_pm_domain *pmd = &scpd->pmd;
> > +
> > +		scp->pmd[i] = pmd;
> > +		scpd->data = &scp_domain_data[i];
> > +		scpd->scp = scp;
> > +
> > +		pmd->name = scp_domain_data[i].name;
> > +		pmd->power_off = scpsys_power_off;
> > +		pmd->power_on = scpsys_power_on;
> > +		pmd->power_off_latency_ns = 20000;
> > +		pmd->power_on_latency_ns = 20000;
> 
> I think I mentioned this before... are these numbers really identical
> for all domains?  I suggest you make these each a field in the domain
> data so they can be different for each domain, and eventually come from
> DT data.

For the record, here are the numbers I just measured:

mtk-scpsys 10006000.scpsys:       vdec on: 31000 off: 10769
mtk-scpsys 10006000.scpsys:       venc on:  6000 off:  5923
mtk-scpsys 10006000.scpsys:        isp on:  5923 off:  5923
mtk-scpsys 10006000.scpsys:         mm on:  7616 off:  7692
mtk-scpsys 10006000.scpsys:    venc_lt on:  5924 off:  6000
mtk-scpsys 10006000.scpsys:      audio on:  5462 off:  5615
mtk-scpsys 10006000.scpsys:        usb on:  5461 off:  5462
mtk-scpsys 10006000.scpsys:  mfg_async on: 29923 off: 11077
mtk-scpsys 10006000.scpsys:     mfg_2d on:  5923 off:  5616
mtk-scpsys 10006000.scpsys:        mfg on: 11231 off: 16153

Anyway, the pm domain core measures these times itself, so there
should not be a need to fill in anything here. I was irritated by the
warning message I got each time when the times were exceeded. This
message seemed to imply that something was wrong and I had to fill
in sane values in the latency fields. Since we now have [1] I'll just
drop the initialisation of these fields.

Sascha

[1]

commit 6d7d5c3266aa946b2049d9fed02186c1a378621b
Author: Russell King <rmk+kernel@....linux.org.uk>
Date:   Fri Mar 20 17:20:28 2015 +0000

    PM / domains: quieten down generic pm domains



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