linux-kernel - Re: [PATCH v2] ARM: tegra: enforce PM requirement

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Message-ID: <562c4307-74ad-fd9d-74e7-36ac19315d0b@gmail.com>
Date:   Tue, 26 Feb 2019 19:52:03 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Russell King - ARM Linux admin <linux@...linux.org.uk>,
        Sameer Pujar <spujar@...dia.com>
Cc:     jhogan@...nel.org, thierry.reding@...il.com, jonathanh@...dia.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] ARM: tegra: enforce PM requirement

26.02.2019 12:13, Russell King - ARM Linux admin пишет:
> On Tue, Feb 26, 2019 at 01:55:37PM +0530, Sameer Pujar wrote:
>> The requirement for this came while adding runtime PM support for HDA
>> driver. There were concerns about driver explicitly handling !PM case.
>> In general, drivers need to handle !PM case with work arounds for
>> managing clocks and power explicitly, which is not really necessary
>> when PM support on tegra is in good shape. In fact ARM 64-bit Tegra
>> platforms enforce PM support and there is no reason why this cannot be
>> done for 32-bit.
>>
>> More details with regards to above can be found in following patch,
>> http://patchwork.ozlabs.org/patch/1036645/
>>
>> This patch selects PM unconditionally and drivers can rely on runtime
>> PM framework for clock and power management.
> 
> What if the drivers are re-used on another SoC IP?  Doesn't this lead
> to unexpected failures?
> 
> If you want to do this, maybe also make those drivers depend on PM as
> well?

The commit message is inaccurate, it is intended for the Tegra HDA driver and not for some generic driver. The overall final intent is to remove dependency on the PM availability for all of Tegra drivers to "make Tegra maintainers life easier".