linux-kernel - Re: [PATCH v2 2/3] regulator: core: add helper to check if regulator is disabled in suspend

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Date:   Thu, 10 Jan 2019 10:24:26 +0000
From:   <Claudiu.Beznea@...rochip.com>
To:     <broonie@...nel.org>
CC:     <Nicolas.Ferre@...rochip.com>, <alexandre.belloni@...tlin.com>,
        <Ludovic.Desroches@...rochip.com>, <linux@...linux.org.uk>,
        <lgirdwood@...il.com>, <rjw@...ysocki.net>, <pavel@....cz>,
        <len.brown@...el.com>, <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <linux-pm@...r.kernel.org>
Subject: Re: [PATCH v2 2/3] regulator: core: add helper to check if regulator
 is disabled in suspend



On 09.01.2019 18:57, Mark Brown wrote:
> On Tue, Jan 08, 2019 at 10:56:32AM +0000, Claudiu.Beznea@...rochip.com wrote:
>> From: Claudiu Beznea <claudiu.beznea@...rochip.com>
>>
>> Add helper to check if regulator will be disabled in suspend.
>>
>> Signed-off-by: Claudiu Beznea <claudiu.beznea@...rochip.com>
> 
> This feels like it's the wrong way round - if this is configurable I'd
> expect something to configure the suspend mode and then for that to
> arrange to configure the regulator appropriately (along with anything
> else that needs doing) rather than to infer the configuration from the
> regulator state which feels fragile.  But based on the cover letter
> that's kind of like what the initial proposal about target states was so
> perhaps this is the way we end up going... 

Are you talking about [1] ?

this certainly looks a lot
> less impactful that the target state stuff though.
> 

For the moment, the patches which describes the regulators states in
suspend for SAMA5D2 Xplained board (which we are trying to address here)
are in pending [2] (they were introduced with patches for act8945a
suspend/resume stuff). Probably they will be introduced after one more
Linux version.

I can get rid of this patch, take advantage of [3] and [4] and introduce
also the regulator standby states. In this case, no matter the mapping b/w
Linux power saving modes and AT91 SoC's power saving modes, we will be
covered on misconfiguration (at least on SAMA5D2 Xplained board).

And in patch 3/3 I could get rid of regulator checks and rely on DT (bad
thing would be that in case of no input for regulator's state in
mem/standby the board could not properly suspended/resumed), if any.

What do you think about this?

Thank you,
Claudiu Beznea

[1] https://patchwork.kernel.org/patch/9458445/
[2]
https://lore.kernel.org/lkml/1544543768-2066-6-git-send-email-claudiu.beznea@microchip.com/
[3]
https://git.kernel.org/pub/scm/linux/kernel/git/broonie/regulator.git/commit/?h=for-next&id=f2b4076988a9c229dab373470b4b108ef0e106c8
[4]
https://git.kernel.org/pub/scm/linux/kernel/git/broonie/regulator.git/commit/?h=for-next&id=5279e96ff8033500b6008be5925ae2d20f42c434