linux-kernel - Re: [PATCH 1/2] regulator: act8945a: rely on hardware for operating mode

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Date:   Mon, 5 Jun 2023 21:46:14 +0530
From:   Raag Jadav <raagjadav@...il.com>
To:     Mark Brown <broonie@...nel.org>
Cc:     Liam Girdwood <lgirdwood@...il.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] regulator: act8945a: rely on hardware for operating
 mode

On Mon, Jun 05, 2023 at 03:44:37PM +0100, Mark Brown wrote:
> On Mon, Jun 05, 2023 at 08:01:03PM +0530, Raag Jadav wrote:
> > On Mon, Jun 05, 2023 at 01:16:33PM +0100, Mark Brown wrote:
> > > On Mon, Jun 05, 2023 at 04:18:29PM +0530, Raag Jadav wrote:
> 
> > > > Convert ->get_mode() and ->set_mode() hooks to read/write operating mode
> > > > from/to hardware instead of relying on driver memory.
> 
> > > Why is this change being made - what is the benefit here?
> 
> > Original implementation uses drvdata to load/store
> > operating mode for the regulator.
> 
> > This change doesn't really add anything new.
> > It is just to make sure that the driver is in sync
> > with the current state of affairs in the hardware
> > instead of relying on locally stored status in the memory.
> 
> It's also removing a cache so we need to talk to the hardware more often
> which doesn't seem like a win.  If there's a bootstapping problem then
> shouldn't we just read once at startup?  If there's no problem what's
> the advantage?

Well, there could be cases of access which are done
outside of driver context or hardware failure,
which are not really ideal but I've faced such problems
a while back, so just decided to share it.

You have the final call on this.

Cheers,
Raag