From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755573Ab1IBUQx (ORCPT ); Fri, 2 Sep 2011 16:16:53 -0400 Received: from mailhost.informatik.uni-hamburg.de ([134.100.9.70]:43326 "EHLO mailhost.informatik.uni-hamburg.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755393Ab1IBUQv (ORCPT ); Fri, 2 Sep 2011 16:16:51 -0400 Message-ID: <4E613986.4040007@metafoo.de> Date: Fri, 02 Sep 2011 22:16:06 +0200 From: Lars-Peter Clausen User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.16) Gecko/20110818 Icedove/3.0.11 MIME-Version: 1.0 To: Dimitris Papastamos CC: linux-kernel@vger.kernel.org, Mark Brown , Liam Girdwood , Graeme Gregory , Samuel Oritz Subject: Re: [PATCH 2/8] regmap: Add the indexed cache support References: <1314978375-11539-1-git-send-email-dp@opensource.wolfsonmicro.com> <1314978375-11539-3-git-send-email-dp@opensource.wolfsonmicro.com> In-Reply-To: <1314978375-11539-3-git-send-email-dp@opensource.wolfsonmicro.com> X-Enigmail-Version: 1.0.1 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/02/2011 05:46 PM, Dimitris Papastamos wrote: > This is the simplest form of a cache available in regcache. Any > registers whose default value is 0 are ignored. If any of those > registers are modified in the future, they will be placed in the > cache on demand. The cache layout is essentially using the provided > register defaults by the regcache core directly and does not re-map > it to another representation. > > Signed-off-by: Dimitris Papastamos I wonder if we really still need indexed caches, because ... > --- > drivers/base/regmap/Makefile | 2 +- > drivers/base/regmap/internal.h | 1 + > drivers/base/regmap/regcache-indexed.c | 65 ++++++++++++++++++++++++++++++++ > drivers/base/regmap/regcache.c | 3 + > include/linux/regmap.h | 1 + > 5 files changed, 71 insertions(+), 1 deletions(-) > create mode 100644 drivers/base/regmap/regcache-indexed.c > > [...] > +static int regcache_indexed_read(struct regmap *map, unsigned int reg, > + unsigned int *value) > +{ > + int ret; > + > + ret = regcache_lookup_reg(map, reg); ... this lookup will be slower than an rbtree lookup. And given that we use two integers per register doesn't give it much size advantage either. I have some patches for the rbtree register cache code, which reduce some of it's complexity and also implements the adjacent node merging and allows smaller holes in the rbnodes register block if the block is smaller then an rbnode. Currently these patches are based on the ASoC register cache code, but they should be easy to rework onto of the regmap register cache code. I did some small statistics on the number of rbnodes without and with the patches applied: Without patches: Nodes: 0: 4000-4000 1 1: 4009-400a 2 2: 400b-400c 2 3: 400d-4010 4 4: 4015-4015 1 5: 4017-4017 1 6: 4019-401b 3 7: 401c-401d 2 8: 401e-4020 3 9: 4021-4022 2 10: 4023-4026 4 11: 4029-402a 2 12: 4031-4031 1 13: 4036-4036 1 14: 40eb-40eb 1 15: 40f2-40f3 2 16: 40f8-40f9 2 17: 40fa-40fa 1 Number of nodes: 18 (504 bytes) Number of registers: 35 (35 bytes) Total size: 539 bytes With patches: Nodes: 0: 4000-4036 55 1: 40eb-40fa 16 Number of nodes: 2 (56 bytes) Number of registers: 71 (71 bytes) Total size: 127 bytes In comparison a ASoC flat cache for this driver would have used 250 bytes and and regmap indexed cache would use 280 bytes. (Not that it really matters at those sizes anyway) > + if (ret < 0) > + *value = 0; > + else > + *value = map->cache_defaults[ret].def; > + return 0; > +} > + > [...] > diff --git a/drivers/base/regmap/regcache.c b/drivers/base/regmap/regcache.c > index 90b7e1f..dfefe40 100644 > --- a/drivers/base/regmap/regcache.c > +++ b/drivers/base/regmap/regcache.c > @@ -16,6 +16,9 @@ > #include "internal.h" > > static const struct regcache_ops *cache_types[] = { > +#ifdef CONFIG_REGCACHE_INDEXED This symbol doesn't seem to be defined anywhere. > + ®cache_indexed_ops, > +#endif > }; > > int regcache_init(struct regmap *map) > diff --git a/include/linux/regmap.h b/include/linux/regmap.h > index b81e86a..4d1ad09 100644 > --- a/include/linux/regmap.h > +++ b/include/linux/regmap.h > @@ -23,6 +23,7 @@ struct spi_device; > /* An enum of all the supported cache types */ > enum regcache_type { > REGCACHE_NONE, > + REGCACHE_INDEXED, > }; > > /**