linux-kernel - Re: [RFC] regmap: allow volatile register writes with cached only read maps

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Message-ID: <20180509083919.GU13402@sirena.org.uk>
Date:   Wed, 9 May 2018 17:39:19 +0900
From:   Mark Brown <broonie@...nel.org>
To:     Jorge Ramirez-Ortiz <jramirez@...libre.com>
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [RFC] regmap: allow volatile register writes with cached only
 read maps

On Wed, May 09, 2018 at 12:06:09AM +0200, Jorge Ramirez-Ortiz wrote:
> Regmap only allows volatile access to registers when the client
> supports both reads and writes.
> 
> This commit bypasses that limitation and enables volatile writes to
> selected registers while maintaining cached accesses on all reads. For
> this, the client does not need to configure the reg_read callback.

I don't understand what voltile access means for write only devices.
Volatile means that we don't read the cache but go direct to the
hardware so if we can't read the hardware that's pretty redundant, a
volatile read that goes to the cache is just a default read.

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