linux-kernel - Re: [PATCH 1/4] Introduce regmap infrastructure over Maxim/Dalas OneWire (W1) bus

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Message-ID: <20170526171834.uq4ke5cm5qtobxgl@sirena.org.uk>
Date:   Fri, 26 May 2017 18:18:34 +0100
From:   Mark Brown <broonie@...nel.org>
To:     Evgeniy Polyakov <zbr@...emap.net>
Cc:     "Alex A. Mihaylov" <minimumlaw@...bler.ru>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Sebastian Reichel <sre@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>
Subject: Re: [PATCH 1/4] Introduce regmap infrastructure over Maxim/Dalas
 OneWire (W1) bus

On Fri, May 26, 2017 at 04:45:12PM +0300, Evgeniy Polyakov wrote:

Please fix your mail client to word wrap within paragraphs at something
substantially less than 80 columns.  Doing this makes your messages much
easier to read and reply to.

> I wonder what is 'cache' argument about? If I know that some read can be cached,
> since underlying hardware never changes these values, I can store it into local variable
> and use it. If I do not know in advance whether given register can be cached,
> how can regmap determine it for me? How to debug cases when register
> was erroneously considered to be cached?

regmap will only cache registers if it was explicitly told to cache, if
the driver gets that wrong it's just your bog standard bug that can be
debugged in the usual ways one might debug things.  By default nothing
will be cached.

> What is the reason to use regmap besides caching?

There's the other reasons I mentioned in the message you're replying
to for a start...

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