linux-kernel - Re: [PATCH V5 11/18] clk: tegra210: Add support for Tegra210 clocks

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Date:   Thu, 18 Jul 2019 19:34:21 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Sowjanya Komatineni <skomatineni@...dia.com>, sboyd@...nel.org,
        Michael Turquette <mturquette@...libre.com>
Cc:     Peter De Schrijver <pdeschrijver@...dia.com>,
        Joseph Lo <josephl@...dia.com>, thierry.reding@...il.com,
        jonathanh@...dia.com, tglx@...utronix.de, jason@...edaemon.net,
        marc.zyngier@....com, linus.walleij@...aro.org, stefan@...er.ch,
        mark.rutland@....com, pgaikwad@...dia.com,
        linux-clk@...r.kernel.org, linux-gpio@...r.kernel.org,
        jckuo@...dia.com, talho@...dia.com, linux-tegra@...r.kernel.org,
        linux-kernel@...r.kernel.org, mperttunen@...dia.com,
        spatra@...dia.com, robh+dt@...nel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH V5 11/18] clk: tegra210: Add support for Tegra210 clocks

18.07.2019 4:15, Sowjanya Komatineni пишет:

[snip]

>>> Please try to fix all missing dependencies and orderings.
>>
>> Peter,
>>
>> dfllCPU_OUT is the first one to go thru restore when
>> clk_restore_context traverses thru the list.
>>
>> dfllCPU_OUT has dependency on DFLL_ref and DFLL_SOC but this
>> dependency is unknown to clock-tree.
>>
>> We can add DFLL_REF and DFLL_SOC as parents to dfllCPU_OUT during
>> register so dfllCPU_OUT save/restore happens after their parents are
>> restored.
>>
>> But DFLL needs both of these to be restored before DFLLCPU_Out and as
>> DFLL_SOC restore always happens after the REF, thinking to add
>> DFLL_SOC as parent to dfllCPU_OUT so save/restore follows after their
>> dependencies.
>>
>> Please comment.
>>
> Did quick try and I see by adding dfll-soc as parent to dfllCPU_OUT, its
> in proper order after all its dependencies.
> 
> Can now add dfll save/restore to do dfll reinit during restore..
> 

If dfllCPU_OUT can work properly with dfll-soc being disabled, then this
kind of dependency isn't very correct and just papers over the real
problem, which is that there should be a way for CCF to specify multiple
dependencies for the clock or the reverse ordering should be used for
the restoring.