Re: [PATCH 2/2] cpufreq: mediatek: Add MT8173 cpufreq driver

From	Viresh Kumar <viresh.kumar@linaro.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH 2/2] cpufreq: mediatek: Add MT8173 cpufreq driver
Date	2015-06-24 11:00 +0200
Message-ID	<pEOHh-4WG-21@gated-at.bofh.it> (permalink)
References	(1 earlier) <pz4vp-74l-11@gated-at.bofh.it> <pE8oG-2AP-13@gated-at.bofh.it> <pEyj9-6AI-41@gated-at.bofh.it> <pEHcJ-2vM-7@gated-at.bofh.it> <pEOxC-4Lc-37@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

On 24-06-15, 16:44, Pi-Cheng Chen wrote:
> One reason to put those initialization and resource allocation in probe is
> that it's easier to handle the return value -PROBE_DEFER from clock
> and regulator framework when trying to get clocks and regulators
> consumed by cpufreq driver.

This is the sequence of events if you move these things to ->init().

- your driver's probe()
  -> cpufreq_register_driver()
    -> init()
      -> clk/reg get, failed, return -EPROBE_DEFER

And the failure here will be propagated to probe(). So, it should
work IMHO.

> The other reason is when the whole system is resuming from suspend,
> the other subsystem e.g. i2c on which cpufreq driver depends might not
> ready yet during cpufreq driver initialization. In this case, the cpufreq
> driver will be blocked when trying to get resources e.g. regulator on i2c
> bus, and the whole system will stuck for seconds.

That's something else you must investigate on. This dependency should
be resolved in some other way, I thought DT might have taken care of
such dependencies.

-- 
viresh
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Thread

Re: [PATCH 2/2] cpufreq: mediatek: Add MT8173 cpufreq driver Viresh Kumar <viresh.kumar@linaro.org> - 2015-06-24 03:00 +0200
  Re: [PATCH 2/2] cpufreq: mediatek: Add MT8173 cpufreq driver Pi-Cheng Chen <pi-cheng.chen@linaro.org> - 2015-06-24 10:50 +0200
    Re: [PATCH 2/2] cpufreq: mediatek: Add MT8173 cpufreq driver Viresh Kumar <viresh.kumar@linaro.org> - 2015-06-24 11:00 +0200
      Re: [PATCH 2/2] cpufreq: mediatek: Add MT8173 cpufreq driver Pi-Cheng Chen <pi-cheng.chen@linaro.org> - 2015-06-24 11:20 +0200

csiph-web