linux-kernel - Re: [PATCH v6 00/18] Consolidate and improve NVIDIA Tegra CPUIDLE driver(s)

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Date:   Wed, 16 Oct 2019 23:14:07 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Peter De Schrijver <pdeschrijver@...dia.com>
Cc:     Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        linux-pm@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 00/18] Consolidate and improve NVIDIA Tegra CPUIDLE
 driver(s)

16.10.2019 22:47, Dmitry Osipenko пишет:
> 16.10.2019 22:21, Peter De Schrijver пишет:
>> On Tue, Oct 15, 2019 at 07:59:57PM +0300, Dmitry Osipenko wrote:
>>> Hello,
>>>
>>> This series does the following:
>>>
>>>   1. Unifies Tegra20/30/114 drivers into a single driver and moves it out
>>>      into common drivers/cpuidle/ directory.
>>>
>>>   2. Enables CPU cluster power-down idling state on Tegra30.
>>>
>>> In the end there is a quite nice clean up of the Tegra CPUIDLE drivers
>>> and of the Tegra's arch code in general. Please review, thanks!
>>>
>>> Changelog:
>>>
>>> v6: - Addressed request from Thierry Reding to change the way patches are
>>>       organized by making changes in a more incremental manner.
>>>
>>>     - tegra_sleep_cpu() now checks for the secondary CPUs to be offline
>>>       in the "Make outer_disable() open-coded" patch.
>>>
>>> v5: - Rebased on a recent linux-next, fixed one minor conflict in Kconfig.
>>>
>>>     - Improved commit's message of the "Support CPU cluster power-down state
>>>       on Tegra30" patch.
>>>
>>>     - The "Support CPU cluster power-down state on Tegra30" patch is also
>>>       got split and now there is additional "Make outer_disable() open-coded"
>>>       patch.
>>>
>>>     - Made minor cosmetic changes to the "Introduce unified driver for
>>>       NVIDIA Tegra SoCs" patch by improving error message and renaming
>>>       one variable.
>>>
>>> v4: - Fixed compilation with !CONFIG_CACHE_L2X0 (and tested that it still
>>>       works).
>>>
>>>     - Replaced ktime_compare() with ktime_before() in the new driver,
>>>       for consistency.
>>>
>>> v3: - Addressed review comments that were made by Jon Hunter to v2 by
>>>       splitting patches into smaller (and simpler) chunks, better
>>>       documenting changes in the commit messages and using proper error
>>>       codes in the code.
>>>
>>>       Warnings are replaced with a useful error messages in the code of
>>>       "Introduce unified driver for NVIDIA Tegra SoCs" patch.
>>>
>>>       Secondary CPUs parking timeout increased to 100ms because I found
>>>       that it actually may happen to take more than 1ms if CPU is running
>>>       on a *very* low frequency.
>>>
>>>       Added diagnostic messages that are reporting Flow Controller state
>>>       when CPU parking fails.
>>>
>>>       Further polished cpuidle driver's code.
>>>
>>>       The coupled state entering is now aborted if there is a pending SGI
>>>       (Software Generated Interrupt) because it will be lost after GIC's
>>>       power-cycling. Like it was done by the old Tegra20 CPUIDLE driver.
>>>
>>> v2: - Added patches to enable the new cpuidle driver in the defconfigs:
>>>
>>>         ARM: multi_v7_defconfig: Enable Tegra cpuidle driver
>>>         ARM: tegra: Enable Tegra cpuidle driver in tegra_defconfig
>>>
>>>     - Dropped patches that removed CPUIDLE_FLAG_TIMER_STOP from the idling
>>>       states because that flag actually doesn't have any negative effects,
>>>       but still is correct for the case of a local CPU timer on older Tegra
>>>       SoCs:
>>>
>>>         cpuidle: tegra: Remove CPUIDLE_FLAG_TIMER_STOP from Tegra114/124 idle-state
>>>         cpuidle: tegra: Remove CPUIDLE_FLAG_TIMER_STOP from all states
>>>
>>>     - The "Add unified driver for NVIDIA Tegra SoCs" patch got more polish.
>>>       Tegra30 and Terga114 states are now squashed into a single common C7
>>>       state (following Parker TRM terminology, see 17.2.2.2 Power Management
>>>       States), more comments added, etc minor changes.
>>
>> It would be useful to switch the power state terminology to the one used
>> for later chips:
>>
>> LP0 becomes SC7
>> LP1 becomes C1
>> LP2 becomes CC7
>>
>> Meaning of these states is as follows
>>
>> C is a core state:
>>
>> C1 clock gating
>> C2 not defined
>> C3 not defined
>> C4 not defined
>> C5 not defined
>> C6 not defined for ARM cores
>> C7 power-gating
>>
>> CC is a CPU cluster C state:
>>
>> CC1 cluster clock gated
>> CC2 not defined
>> CC3 fmax@...n: not used prior to Tegra186
>> CC4: cluster retention: no longer supported
>> CC5: not defined
>> CC6: cluster power gating
>> CC7: cluster rail gating
>>
>> SC is a System C state:
>>
>> SC1: not defined
>> SC2: not defined
>> SC3: not defined
>> SC4: not defined
>> SC5: not defined
>> SC6: not defined
>> SC7: VDD_SOC off
> 
> Hello Peter,
> 
> But new "drivers/cpuidle/cpuidle-tegra.c" uses exactly that terminology,
> please see "cpuidle: Refactor and move NVIDIA Tegra20 driver into
> drivers/cpuidle/" and further patches. Am I missing something? Or do you
> want the renaming to be a separate patch?
> 

Or maybe you're suggesting to change the names everywhere and not only
in the cpuidle driver? Please clarify :)