Re: Lockdep warning when using REGCACHE_RBTREE

From	Stefan Agner <stefan@agner.ch>
Newsgroups	linux.kernel
Subject	Re: Lockdep warning when using REGCACHE_RBTREE
Date	2016-01-15 20:20 +0100
Message-ID	<qRi4G-204-15@gated-at.bofh.it> (permalink)
References	<qQYIG-5f6-19@gated-at.bofh.it> <qR07M-6ou-9@gated-at.bofh.it> <qR1dw-76Q-7@gated-at.bofh.it> <qRfqb-cf-41@gated-at.bofh.it>
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On 2016-01-15 08:28, Mark Brown wrote:
> On Thu, Jan 14, 2016 at 05:14:47PM -0800, Stefan Agner wrote:
> 
>> On a slightly other topic, I question whether REGCACHE_RBTREE is the
>> right cache type for the DCU DRM driver. The driver has uses a regmap
>> area of 1144 32-bit registers, the most space is used by the layer
>> configuration registers which are 0x40 apart and 0x0-0x20 for each layer
>> are actually used (hence somewhat above 50%).
> 
>> Would FLAT be the better cache type?
> 
> Yes, and if it's a MMIO device the performance of a flat cache is more
> in line with the device performance.

Thanks for confirming that. I will switch to REGCACHE_FLAT then, I found
a second driver with the very same issue, also a MMIO mapped device:
drivers/pwm/pwm-fsl-ftm.c...

--
Stefan

Thread

Lockdep warning when using REGCACHE_RBTREE Stefan Agner <stefan@agner.ch> - 2016-01-14 23:40 +0100
  Re: Lockdep warning when using REGCACHE_RBTREE Mark Brown <broonie@kernel.org> - 2016-01-15 01:10 +0100
    Re: Lockdep warning when using REGCACHE_RBTREE Stefan Agner <stefan@agner.ch> - 2016-01-15 02:20 +0100
      Re: Lockdep warning when using REGCACHE_RBTREE Mark Brown <broonie@kernel.org> - 2016-01-15 17:30 +0100
        Re: Lockdep warning when using REGCACHE_RBTREE Stefan Agner <stefan@agner.ch> - 2016-01-15 20:20 +0100
  Re: Lockdep warning when using REGCACHE_RBTREE Peter Zijlstra <peterz@infradead.org> - 2016-01-15 10:50 +0100
    Re: Lockdep warning when using REGCACHE_RBTREE Mark Brown <broonie@kernel.org> - 2016-01-15 13:00 +0100

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