linux-kernel - Re: [RFC][PATCH] regmap: Add support for sequences of writes with specified delays

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Message-ID: <20150526152100.GR21577@sirena.org.uk>
Date:	Tue, 26 May 2015 16:21:00 +0100
From:	Mark Brown <broonie@...nel.org>
To:	Nariman Poushin <nariman@...nsource.wolfsonmicro.com>
Cc:	patches@...nsource.wolfsonmicro.com, gregkh@...uxfoundation.org,
	linux-kernel@...r.kernel.org
Subject: Re: [RFC][PATCH] regmap: Add support for sequences of writes with
 specified delays

On Tue, May 26, 2015 at 01:39:21PM +0100, Nariman Poushin wrote:

> Change-Id:Ie9e77aa48f258b353ffa7406d02e19c28d5f2a44

Please don't include noise like this in upstream patches.

> +		if (regs[i].delay_us)
> +			udelay(regs[i].delay_us);

This should be a usleep_range() at least (as checkpatch should have told
you).

> +int regmap_sequence_write(struct regmap *map, const struct reg_sequence *regs,
> +			  int num_regs);

It's a bit sad that this is a separate interface to the existing
sequence writing interface (_multi_reg_write() and _patch()), and
especially that it's a separate implementation.  This means that if
something needs a delay in the sequence it won't get to take advantage
of any optimisations that the rest of the implementations get.

Of course the fact that we used the same struct for both sequences and
the register defaults makes this a bit annoying.  We could either just
add the extra field to the defaults and ignore it (we don't have *that*
many defaults) or just update the existing users to use the new struct
with the additional delay field (which is also fairly straightforward as
we have few users right now).

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