linux-kernel - Re: [PATCH v2 1/4] nvmem: rockchip-efuse: Change initcall to subsys

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Date:   Fri, 19 Aug 2016 11:19:13 -0500
From:   Kevin Hilman <khilman@...libre.com>
To:     Heiko Stuebner <heiko@...ech.de>
Cc:     Finlye Xiao <finley.xiao@...k-chips.com>,
        srinivas.kandagatla@...aro.org, maxime.ripard@...e-electrons.com,
        robh+dt@...nel.org, frowand.list@...il.com, sre@...nel.org,
        dbaryshkov@...il.com, dwmw2@...radead.org, mark.rutland@....com,
        nm@...com, rjw@...ysocki.net, viresh.kumar@...aro.org,
        sboyd@...eaurora.org, linux-arm-kernel@...ts.infradead.org,
        linux-rockchip@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        wxt@...k-chips.com, jay.xu@...k-chips.com,
        rocky.hao@...k-chips.com, tim.chen@...k-chips.com,
        tony.xie@...k-chips.com, ulysses.huang@...k-chips.com,
        lin.huang@...k-chips.com
Subject: Re: [PATCH v2 1/4] nvmem: rockchip-efuse: Change initcall to subsys

Heiko Stuebner <heiko@...ech.de> writes:

> Am Donnerstag, 18. August 2016, 13:28:58 CEST schrieb Kevin Hilman:
>> Finlye Xiao <finley.xiao@...k-chips.com> writes:
>> > From: Finley Xiao <finley.xiao@...k-chips.com>
>> > 
>> > We will register a cpufreq notifier for adjusting opp's voltage, and it
>> > need to fetch cpu's leakage from efuse in the notifier_call. so the efuse
>> > driver should probe before cpufreq driver.
>> > 
>> > Signed-off-by: Finley Xiao <finley.xiao@...k-chips.com>
>> 
>> Why can't this be handled with deferred probling?  initcall ordering is
>> a can of worms.
>
> I think the issue is less between efuse and avs driver, but more between avs 
> driver and cpufreq. The avs driver aims to modify the opp table and thus wants 
> to do that / register the notifier before cpufreq starts.
>
> And as there is no direct connection between cpufreq and the avs driver, 
> making cpufreq defer probing is probably not really easy.

Thanks for the explanation.

Sounds like something that belongs in the changelog.

Kevin