linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Sudeep Holla <sudeep.holla@arm.com>
To: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Linux PM <linux-pm@vger.kernel.org>,
	Linux ACPI <linux-acpi@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Viresh Kumar <viresh.kumar@linaro.org>,
	Sudeep Holla <sudeep.holla@arm.com>,
	Dmitry Osipenko <digetx@gmail.com>
Subject: Re: [RFT][PATCH 0/3] cpufreq / PM: QoS: Introduce frequency QoS and use it in cpufreq
Date: Wed, 16 Oct 2019 15:23:43 +0100	[thread overview]
Message-ID: <20191016142343.GB5330@bogus> (raw)
In-Reply-To: <2811202.iOFZ6YHztY@kreacher>

On Wed, Oct 16, 2019 at 12:37:58PM +0200, Rafael J. Wysocki wrote:
> Hi All,
>
> The motivation for this series is to address the problem discussed here:
>
> https://lore.kernel.org/linux-pm/5ad2624194baa2f53acc1f1e627eb7684c577a19.1562210705.git.viresh.kumar@linaro.org/T/#md2d89e95906b8c91c15f582146173dce2e86e99f
>
> and also reported here:
>
> https://lore.kernel.org/linux-pm/20191015155735.GA29105@bogus/
>
> Plus, generally speaking, using the policy CPU as a proxy for the policy
> with respect to PM QoS does not feel particularly straightforward to me
> and adds extra complexity.
>
> Anyway, the first patch adds frequency QoS that is based on "raw" PM QoS (kind
> of in analogy with device PM QoS) and is just about min and max frequency
> requests (no direct relationship to devices).
>
> The second patch switches over cpufreq and its users to the new frequency QoS.
> [The Fixes: tag has been tentatively added to it.]
>
> The third one removes frequency request types from device PM QoS.
>
> Unfortunately, the patches are rather big, but also they are quite
> straightforward.
>
> I didn't have the time to test this series, so giving it a go would be much
> appreciated.

Thanks for the spinning these patches so quickly.

I did give it a spin, but unfortunately it doesn't fix the bug I reported.
So I looked at my bug report in detail and looks like the cpufreq_driver
variable is set to NULL at that point and it fails to dereference it
while trying to execute:
	ret = cpufreq_driver->verify(new_policy);
(Hint verify is at offset 0x1c/28)

So I suspect some race as this platform with bL switcher tries to
unregister and re-register the cpufreq driver during the boot.

I need to spend more time on this as reverting the initial PM QoS patch
to cpufreq.c makes the issue disappear.

--
Regards,
Sudeep

  parent reply	other threads:[~2019-10-16 14:23 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-16 10:37 Rafael J. Wysocki
2019-10-16 10:41 ` [RFT][PATCH 1/3] PM: QoS: Introduce frequency QoS Rafael J. Wysocki
2019-10-17  9:41   ` Viresh Kumar
2019-10-17 14:16     ` Rafael J. Wysocki
2019-10-18  5:41       ` Viresh Kumar
2019-10-24 19:01   ` Leonard Crestez
2019-10-24 19:34     ` Leonard Crestez
2019-11-17  7:34   ` Doug Smythies
2019-11-17 16:13   ` Doug Smythies
2019-11-19 14:35     ` Doug Smythies
2019-11-19 19:17       ` Rafael J. Wysocki
2019-11-19 22:13         ` Rafael J. Wysocki
2019-11-20  6:55           ` Doug Smythies
2019-11-20  9:08             ` Rafael J. Wysocki
2019-10-16 10:47 ` [RFT][PATCH 2/3] cpufreq: Use per-policy " Rafael J. Wysocki
2019-10-16 18:01   ` Dmitry Osipenko
2019-10-17 21:29     ` Dmitry Osipenko
2019-10-18  9:29       ` Viresh Kumar
2019-10-18 15:31         ` Dmitry Osipenko
2019-10-16 10:47 ` [RFT][PATCH 3/3] PM: QoS: Drop frequency QoS types from device PM QoS Rafael J. Wysocki
2019-10-16 14:23 ` Sudeep Holla [this message]
2019-10-17  9:57   ` [RFT][PATCH 0/3] cpufreq / PM: QoS: Introduce frequency QoS and use it in cpufreq Viresh Kumar
2019-10-17  9:59     ` Sudeep Holla
2019-10-17 16:34       ` Rafael J. Wysocki
2019-10-17 16:42         ` Sudeep Holla
2019-10-18  5:44         ` Viresh Kumar
2019-10-18  8:24           ` Rafael J. Wysocki
2019-10-18  8:27             ` Viresh Kumar
2019-10-18  8:30               ` Rafael J. Wysocki
2019-10-18  9:24                 ` Viresh Kumar
2019-10-18  9:26                   ` Rafael J. Wysocki
2019-10-18  9:28                     ` Viresh Kumar
2019-10-17 17:14   ` Sudeep Holla
2019-10-17  9:46 ` Viresh Kumar

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=20191016142343.GB5330@bogus \
    --to=sudeep.holla@arm.com \
    --cc=digetx@gmail.com \
    --cc=linux-acpi@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-pm@vger.kernel.org \
    --cc=rjw@rjwysocki.net \
    --cc=viresh.kumar@linaro.org \
    --subject='Re: [RFT][PATCH 0/3] cpufreq / PM: QoS: Introduce frequency QoS and use it in cpufreq' \
    /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

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).