From: Brian Norris <briannorris@chromium.org>
To: Matthias Kaehlcke <mka@chromium.org>
Cc: MyungJoo Ham <myungjoo.ham@samsung.com>,
Kyungmin Park <kyungmin.park@samsung.com>,
Chanwoo Choi <cw00.choi@samsung.com>,
Arnd Bergmann <arnd@arndb.de>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Rob Herring <robh+dt@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
linux-pm@vger.kernel.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org,
Douglas Anderson <dianders@chromium.org>,
Enric Balletbo i Serra <enric.balletbo@collabora.com>,
"Rafael J . Wysocki" <rjw@rjwysocki.net>,
Viresh Kumar <viresh.kumar@linaro.org>,
Lee Jones <lee.jones@linaro.org>
Subject: Re: [PATCH v3 02/12] PM / devfreq: Fix handling of min/max_freq == 0
Date: Mon, 18 Jun 2018 13:12:41 -0700 [thread overview]
Message-ID: <20180618201239.GA153862@rodete-desktop-imager.corp.google.com> (raw)
In-Reply-To: <20180614194712.102134-3-mka@chromium.org>
Hi,
On Thu, Jun 14, 2018 at 12:47:02PM -0700, Matthias Kaehlcke wrote:
> Commit ab8f58ad72c4 ("PM / devfreq: Set min/max_freq when adding the
> devfreq device") initializes df->min/max_freq with the min/max OPP when
> the device is added. Later commit f1d981eaecf8 ("PM / devfreq: Use the
> available min/max frequency") adds df->scaling_min/max_freq and the
> following to the frequency adjustment code:
>
> max_freq = MIN(devfreq->scaling_max_freq, devfreq->max_freq);
>
> With the current handling of min/max_freq this is incorrect:
>
> Even though df->max_freq is now initialized to a value != 0 user space
> can still set it to 0, in this case max_freq would be 0 instead of
> df->scaling_max_freq as intended. In consequence the frequency adjustment
> is not performed:
>
> if (max_freq && freq > max_freq) {
> freq = max_freq;
>
> To fix this set df->min/max freq to the min/max OPP in max/max_freq_store,
> when the user passes a value of 0. This also prevents df->max_freq from
> being set below the min OPP when df->min_freq is 0, and similar for
> min_freq. Since it is now guaranteed that df->min/max_freq can't be 0 the
> checks for this case can be removed.
>
> Fixes: f1d981eaecf8 ("PM / devfreq: Use the available min/max frequency")
> Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
FWIW, I've reviewed patches 1-9 (the core devfreq bugfixes and features,
and a small cpufreq helper fixup), and they seem pretty clear and good
to me, aside from a minor error in the current subject
(s/devfreg/devfreq/). So:
Reviewed-by: Brian Norris <briannorris@chromium.org>
next prev parent reply other threads:[~2018-06-18 20:12 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-14 19:47 [PATCH v3 00/12] Add throttler driver for non-thermal throttling Matthias Kaehlcke
2018-06-14 19:47 ` [PATCH v3 01/12] PM / devfreq: Init user limits from OPP limits, not viceversa Matthias Kaehlcke
2018-06-15 21:06 ` Brian Norris
2018-06-15 21:25 ` Matthias Kaehlcke
2018-06-14 19:47 ` [PATCH v3 02/12] PM / devfreq: Fix handling of min/max_freq == 0 Matthias Kaehlcke
2018-06-18 20:12 ` Brian Norris [this message]
2018-06-14 19:47 ` [PATCH v3 03/12] PM / devfreq: Don't adjust to user limits in governors Matthias Kaehlcke
2018-06-14 19:47 ` [PATCH v3 04/12] PM / devfreq: Add struct devfreq_policy Matthias Kaehlcke
2018-06-14 19:47 ` [PATCH v3 05/12] PM / devfreg: Add support for policy notifiers Matthias Kaehlcke
2018-06-14 19:47 ` [PATCH v3 06/12] PM / devfreq: Make update_devfreq() public Matthias Kaehlcke
2018-06-14 19:47 ` [PATCH v3 07/12] PM / devfreq: export devfreq_class Matthias Kaehlcke
2018-06-14 19:47 ` [PATCH v3 08/12] cpufreq: Add stub for cpufreq_update_policy() Matthias Kaehlcke
2018-06-14 19:47 ` [PATCH v3 09/12] dt-bindings: PM / OPP: add opp-throttlers property Matthias Kaehlcke
2018-06-14 19:47 ` [PATCH v3 10/12] misc: throttler: Add core support for non-thermal throttling Matthias Kaehlcke
2018-06-18 23:03 ` Brian Norris
2018-06-18 23:59 ` Matthias Kaehlcke
2018-06-14 19:47 ` [PATCH v3 11/12] misc: throttler: Add Chrome OS EC throttler Matthias Kaehlcke
2018-06-18 23:34 ` Brian Norris
2018-06-14 19:47 ` [PATCH v3 12/12] mfd: cros_ec: Add throttler sub-device Matthias Kaehlcke
2018-06-18 23:21 ` Brian Norris
2018-06-19 8:41 ` Enric Balletbo Serra
2018-06-19 17:55 ` Matthias Kaehlcke
2018-06-19 17:43 ` Matthias Kaehlcke
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