Re: Lockdep warning when using REGCACHE_RBTREE

From: Stefan Agner
Date: Fri Jan 15 2016 - 14:10:46 EST

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: