linux-kernel - Re: [RFT PATCH] regmap-i2c: Only use I2C_FUNC_I2C if val

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Message-ID: <20160625113409.GA28202@sirena.org.uk>
Date:	Sat, 25 Jun 2016 12:34:09 +0100
From:	Mark Brown <broonie@...nel.org>
To:	Guenter Roeck <linux@...ck-us.net>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-kernel@...r.kernel.org, Nishanth Menon <nm@...com>
Subject: Re: [RFT PATCH] regmap-i2c: Only use I2C_FUNC_I2C if val_bits == 8

On Fri, Jun 24, 2016 at 07:53:53PM -0700, Guenter Roeck wrote:

> On chips with a register value size of 16 bits, I2C block reads will
> typically not return the expected values. Instead, returned values
> are most likely undefined if an operation crosses a register boundary.

No, this just isn't true in general - if a device has trouble with bulk
reads it needs to set use_sigle_rw in the config to disable them.
Device limitations with bulk reads are a per device thing and are
orthogonal to the value size, being more to do with the age and quality
of the register map implementation than anything else.

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