From: Shawn Guo <shawn.guo@linaro.org>
To: Rongjun Ying <Rongjun.Ying@csr.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>, rjying <rjying@gmail.com>,
"Rafael J. Wysocki" <rjw@sisk.pl>,
"cpufreq@vger.kernel.org" <cpufreq@vger.kernel.org>,
"linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
"rongjun.ying@gcsr.com" <rongjun.ying@gcsr.com>
Subject: Re: [PATCH 1/1] cpufreq: cpufreq-cpu0: use the max voltage instead of voltage-tolerance
Date: Wed, 6 Nov 2013 11:27:44 +0800 [thread overview]
Message-ID: <20131106032742.GP19770@S2101-09.ap.freescale.net> (raw)
In-Reply-To: <86130EF012BDF348AA0D464A4F44947801295423DF@SHAASIEXM01.ASIA.ROOT.PRI>
On Wed, Nov 06, 2013 at 02:15:07AM +0000, Rongjun Ying wrote:
> If omit voltage-tolerance, sometimes also can't get appropriate voltages.
> For example:
> If the regulator IC only can supply min voltage is 1.000V and max voltage is 1.200V, and cpu work max voltage is 1.200V.
> But the cpu just need 1.100V when cpu run under a freq.
> So regulator_set_voltage_tol will return failed.
> Because the regulator_set_voltage will invoke with min-uV is 1100000 and max-uV is 1100000 parameters.
> Regulator can't supply it.
> As this case, the regulator just need supply 1.200V.
For given board, what voltages could be provided is known. So you can
just define OPP table in <board>.dts and specify the voltage as the
value that the regulator IC can supply, e.g. 1.200V in above example.
This is not nice, as OPP table is CPU/SoC specific and should be ideally
defined in <soc>.dtsi. But still it's a way out for you to use
cpufreq-cpu0 driver as it is.
In any case, you can not just change voltage-tolerance to voltage-max
with no care about the existing users.
Shawn
next prev parent reply other threads:[~2013-11-06 3:27 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-05 3:10 [PATCH 1/1] cpufreq: cpufreq-cpu0: use the max voltage instead of voltage-tolerance rjying
2013-11-05 4:38 ` Viresh Kumar
2013-11-05 11:53 ` Shawn Guo
2013-11-06 2:15 ` Rongjun Ying
2013-11-06 3:27 ` Shawn Guo [this message]
2013-11-07 1:55 ` Rongjun Ying
2013-11-07 2:26 ` Shawn Guo
2013-11-07 3:32 ` Rongjun Ying
2013-11-07 4:55 ` Shawn Guo
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20131106032742.GP19770@S2101-09.ap.freescale.net \
--to=shawn.guo@linaro.org \
--cc=Rongjun.Ying@csr.com \
--cc=cpufreq@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pm@vger.kernel.org \
--cc=rjw@sisk.pl \
--cc=rjying@gmail.com \
--cc=rongjun.ying@gcsr.com \
--cc=viresh.kumar@linaro.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).