linux-kernel - Re: [PATCH 0/7] ARM: davinci: add genpd support

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Date:   Mon, 19 Feb 2018 11:49:07 +0100
From:   Bartosz Golaszewski <bgolaszewski@...libre.com>
To:     David Lechner <david@...hnology.com>
Cc:     Sekhar Nori <nsekhar@...com>, Bartosz Golaszewski <brgl@...ev.pl>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Kevin Hilman <khilman@...nel.org>,
        Russell King <linux@...linux.org.uk>,
        linux-devicetree <devicetree@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        arm-soc <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 0/7] ARM: davinci: add genpd support

2018-02-18 4:41 GMT+01:00 David Lechner <david@...hnology.com>:
> On 02/09/2018 06:42 AM, Sekhar Nori wrote:
>>
>> Hi David,
>>
>> On Thursday 08 February 2018 04:13 AM, David Lechner wrote:
>>>
>>> On 02/07/2018 07:45 AM, Bartosz Golaszewski wrote:
>>>>
>>>> From: Bartosz Golaszewski <bgolaszewski@...libre.com>
>>>>
>>>> Hi Sekhar et al,
>>>>
>>>> please take a look at the following patches. They add a simple genpd
>>>> driver and use it in DT mode on da850 boards.
>>>>
>>>> I was trying to use genpd in legacy mode too, but couldn't find neither
>>>> any interfaces nor users that would do that. For now I added a check in
>>>> arch/arm/mach-davinci/pm_domain.c that disables the clock pm setup if
>>>> we're using genpd.
>>>>
>>>> This series applies on top of and has been tested with David Lechner's
>>>> for-bartosz branch. It fixes the clock look-up issues we faced with
>>>> lcdc and emac.
>>>
>>>
>>> I'm starting to think that it makes more sense to just make the PSC
>>> driver
>>> a power-domain and reset provider rather than a clock provider. It is
>>> unfortunate that genpd is DT only.
>>
>>
>> This will mean that the only way to enable clocks on DaVinci is to use
>> pm_runtime() calls. We do still have drivers which depend on clk api for
>> enabling clocks, so I am not sure its feasible just yet.
>>
>> I think a question like this can arise for any gate clock.
>>
>
> I've incorporated parts of this series into my v7 work in progress
> using the suggestions I made about using the existing PSC device
> as the power domain provider.
>

FYI I had added the power domain functionality to the v6 PSC driver
here: https://github.com/brgl/linux/commits/topic/davinci-genpd-final-v2

Thanks,
Bartosz