linux-kernel - Re: [PATCH v2 0/9] Exynos Adaptive Supply Voltage support

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Message-ID: <20190819112533.bvfyinw7fsebkufr@vireshk-i7>
Date:   Mon, 19 Aug 2019 16:55:33 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Sylwester Nawrocki <s.nawrocki@...sung.com>
Cc:     Marek Szyprowski <m.szyprowski@...sung.com>, krzk@...nel.org,
        robh+dt@...nel.org, vireshk@...nel.org, devicetree@...r.kernel.org,
        kgene@...nel.org, pankaj.dubey@...sung.com,
        linux-samsung-soc@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org, b.zolnierkie@...sung.com
Subject: Re: [PATCH v2 0/9] Exynos Adaptive Supply Voltage support

On 19-08-19, 13:16, Sylwester Nawrocki wrote:
> On 8/19/19 11:09, Viresh Kumar wrote:
> > Will something like this help ?
> > 
> > https://lore.kernel.org/lkml/1442623929-4507-3-git-send-email-sboyd@codeaurora.org/
> > 
> > This never got merged but the idea was AVS only.
> 
> It's quite interesting work, it seems to be for a more advanced use case 
> where OPP voltage is being adjusted at runtime.
> 
> We could use it instead of removing an OPP and then adding with updated 
> voltage. On Exynos there is there is just a need to update OPPs once at boot 
> time, so it is more "static". However the requirements could presumably 
> change in future.

The API is about changing the values after they are parsed once from DT. You can
change it once or multiple times depending on the use case.

> If that's your preference I could switch to that notifier approach.

You shouldn't be required to use the notifier. Just add the OPP table and update
the values right after that. So no one would be using the values at that time.

> AFAICS the API would still need to be extended to support multiple voltages,
> when in future we add support for the Body Bias regulator. 

Right.

Will this patchset solve the problems for you and make your DT light weight ?

-- 
viresh