linux-kernel - Re: [RFC PATCH v2] regmap: smbus: add support for regmap over SMBus

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Date:	Tue, 15 Apr 2014 13:10:42 +0100
From:	Mark Brown <broonie@...nel.org>
To:	Boris BREZILLON <boris.brezillon@...e-electrons.com>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Maxime Ripard <maxime.ripard@...e-electrons.com>,
	Shuge <shuge@...winnertech.com>, kevin@...winnertech.com,
	Chen-Yu Tsai <wens@...e.org>,
	Hans de Goede <hdegoede@...hat.com>,
	Carlo Caione <carlo@...one.org>,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	dev@...ux-sunxi.org
Subject: Re: [RFC PATCH v2] regmap: smbus: add support for regmap over SMBus

On Tue, Apr 15, 2014 at 01:54:02PM +0200, Boris BREZILLON wrote:
> On 15/04/2014 12:09, Mark Brown wrote:

> > OK, so if this a realistic issue then it seems like it's better to
> > implement three different buses - there is not really any common code
> > between the various paths.

> Okay, I'll create 4 different busses (one for each access type).
> BTW, should I keep these implementations in the same source file
> (regmap-smbus.c) ?
> And, should I keep one method to register an smbus regmap or should I
> provide one method per access type and get rid of the
> regmap_smbus_transfer_type enum ?

Do something that looks tasteful in implementation.

> >   This would also mean that you avoid having
> > gather write when it can't be implemented.

> Correct me if I'm wrong, but they all support gather write.

Everything except for the block transfers is writing one register at a
time, actually looking again everything that can only write one register
at a time ought not to be implementing the buffer based stuff at all and
should instead be hooked into reg_read() and reg_write() - it's not able
to implement the API properly in any of the cases, it's unpacking the
buffer which the upper level code already supports.

> > The code is also not validating the lengths for two byte values.

> I'm not sure I get this one.
> Do you mean I should check that val_size is a 2 byte multiple ?
> If this is what you meant, then I should also check it for block transfers.

Yes.

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