linux-kernel - [PATCH] regmap: make LZO cache optional

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Message-Id: <20170602131537.22180-1-jonas.gorski@gmail.com>
Date:   Fri,  2 Jun 2017 15:15:37 +0200
From:   Jonas Gorski <jonas.gorski@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     Mark Brown <broonie@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Dimitris Papastamos <dp@...nsource.wolfsonmicro.com>
Subject: [PATCH] regmap: make LZO cache optional

Commit 2cbbb579bcbe3 ("regmap: Add the LZO cache support") added support
for LZO compression in regcache, but there were never any users added
afterwards. Since LZO support itself has its own size, it currently is
rather a deoptimization.

So make it optional by introducing a symbol that can be selected by
drivers wanting to make use of it.

Saves e.g. ~46 kB on MIPS (size of LZO support + regcache LZO code).

Signed-off-by: Jonas Gorski <jonas.gorski@...il.com>
---
I tried using google to find any users (even out-of-tree ones), but at
best I found a single driver submission that was switched to RBTREE in
subsequent resubmissions (MFD_SMSC).

One could maybe also just drop the code because of no users for 5 years,
but that would be up to the maintainer(s) to decide.

 drivers/base/regmap/Kconfig    | 5 ++++-
 drivers/base/regmap/Makefile   | 3 ++-
 drivers/base/regmap/regcache.c | 2 ++
 3 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/base/regmap/Kconfig b/drivers/base/regmap/Kconfig
index db9d00c36a3e..48b3fc1ee514 100644
--- a/drivers/base/regmap/Kconfig
+++ b/drivers/base/regmap/Kconfig
@@ -4,9 +4,12 @@
 
 config REGMAP
 	default y if (REGMAP_I2C || REGMAP_SPI || REGMAP_SPMI || REGMAP_AC97 || REGMAP_MMIO || REGMAP_IRQ)
+	select IRQ_DOMAIN if REGMAP_IRQ
+	bool
+
+config REGCACHE_COMPRESSED
 	select LZO_COMPRESS
 	select LZO_DECOMPRESS
-	select IRQ_DOMAIN if REGMAP_IRQ
 	bool
 
 config REGMAP_AC97
diff --git a/drivers/base/regmap/Makefile b/drivers/base/regmap/Makefile
index 609e4c84f485..6271ea9b758a 100644
--- a/drivers/base/regmap/Makefile
+++ b/drivers/base/regmap/Makefile
@@ -2,7 +2,8 @@
 CFLAGS_regmap.o := -I$(src)
 
 obj-$(CONFIG_REGMAP) += regmap.o regcache.o
-obj-$(CONFIG_REGMAP) += regcache-rbtree.o regcache-lzo.o regcache-flat.o
+obj-$(CONFIG_REGMAP) += regcache-rbtree.o regcache-flat.o
+obj-$(CONFIG_REGCACHE_COMPRESSED) += regcache-lzo.o
 obj-$(CONFIG_DEBUG_FS) += regmap-debugfs.o
 obj-$(CONFIG_REGMAP_AC97) += regmap-ac97.o
 obj-$(CONFIG_REGMAP_I2C) += regmap-i2c.o
diff --git a/drivers/base/regmap/regcache.c b/drivers/base/regmap/regcache.c
index b0a0dcf32fb7..f3a435ee5fe8 100644
--- a/drivers/base/regmap/regcache.c
+++ b/drivers/base/regmap/regcache.c
@@ -21,7 +21,9 @@
 
 static const struct regcache_ops *cache_types[] = {
 	&regcache_rbtree_ops,
+#if IS_ENABLED(CONFIG_REGCHACHE_COMPRESSED)
 	&regcache_lzo_ops,
+#endif
 	&regcache_flat_ops,
 };
 
-- 
2.11.0