linux-kernel - Re: [PATCH v2 8/9] regulator/rpi-panel-attiny: Don't read the LCD power status

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Date:   Mon, 24 Jan 2022 15:22:35 -0500
From:   Detlev Casanova <detlev.casanova@...labora.com>
To:     Mark Brown <broonie@...nel.org>
Cc:     linux-kernel@...r.kernel.org,
        Dave Stevenson <dave.stevenson@...pberrypi.com>,
        Liam Girdwood <lgirdwood@...il.com>
Subject: Re: [PATCH v2 8/9] regulator/rpi-panel-attiny: Don't read the LCD power status

On Friday, January 21, 2022 11:30:39 A.M. EST Mark Brown wrote:
> On Fri, Jan 21, 2022 at 10:20:55AM -0500, Detlev Casanova wrote:
> > From: Dave Stevenson <dave.stevenson@...pberrypi.com>
> > 
> > The I2C to the Atmel is very fussy, and locks up easily on
> > Pi0-3 particularly on reads.
> > 
> > The LCD power status is controlled solely by this driver, so
> > rather than reading it back from the Atmel, use the cached
> > status last set.
> 
> If that's the case since you're using regmap would it not make sense to
> enable caching in order to minimise reads in general.

Would caching avoid all reads if the values are written at least once before? 
The idea here is to make sure they are never read, I'm not sure if the regmap 
cache ensures no read in this situation.