linux-kernel - Re: Lockdep warning when using REGCACHE

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Message-ID: <20160115114946.GV6588@sirena.org.uk>
Date:	Fri, 15 Jan 2016 11:49:46 +0000
From:	Mark Brown <broonie@...nel.org>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Stefan Agner <stefan@...er.ch>, festevam@...il.com,
	mingo@...hat.com, linux-kernel@...r.kernel.org,
	dri-devel@...ts.freedesktop.org
Subject: Re: Lockdep warning when using REGCACHE_RBTREE

On Fri, Jan 15, 2016 at 10:45:41AM +0100, Peter Zijlstra wrote:

> So _regmap_write() does: map->lock(map->lock_arg)

> Which isn't very enlightening, since that can be a mutex or a spinlock,
> the above strongly suggests spinlock though.

> Looking at __regmap_init(), this seems to depend on:

>   (bus && bus->fast_io) || config->fast_io

> now, afaict, regmap_mmio is used in this case, which has .fast_io =
> true.

> So yeah, fail.

Indeed, that'd do it.  It hadn't occurred to me that someone would be
using MMIO with an rbtree cache.

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