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

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Date:   Fri, 19 Aug 2016 00:29:55 +0200
From:   Heiko Stuebner <heiko@...ech.de>
To:     Kevin Hilman <khilman@...libre.com>
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

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.