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

From: Dmitry Osipenko <digetx@gmail.com>
To: Peter De Schrijver <pdeschrijver@nvidia.com>,
	Thierry Reding <thierry.reding@gmail.com>,
	Jonathan Hunter <jonathanh@nvidia.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Daniel Lezcano <daniel.lezcano@linaro.org>,
	linux-pm@vger.kernel.org, linux-tegra@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v6 00/18] Consolidate and improve NVIDIA Tegra CPUIDLE driver(s)
Date: Tue, 29 Oct 2019 03:47:56 +0300	[thread overview]
Message-ID: <40de641f-c38e-51ee-ae27-c5db468c45b5@gmail.com> (raw)
In-Reply-To: <20191028140443.GA27141@pdeschrijver-desktop.Nvidia.com>

28.10.2019 17:04, Peter De Schrijver пишет:
> On Wed, Oct 16, 2019 at 11:14:07PM +0300, Dmitry Osipenko wrote:
>> 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@Vmin: 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 :)
> 
> At least some of the variable and function names still say lp2?

The cpuidle driver uses LP2 terminology for everything that comes from
the external arch / firmware includes. But it says CC6 for everything
that is internal to the driver. So yes, there is a bit of new/old
terminology mixing in the code.

The arch code / PMC driver / TF firmware are all saying LP2. The LP2
naming is also a part of the device-tree binding.

It will be a lot of mess to rename the mach-tegra/pm.c code. I guess
eventually it could be moved to drivers/soc/, so maybe it will be better
to postpone the renaming until then?