kernel: make regmap LZO cache optional

There are no users, so hide it and let future users select it. Saves
about ~17 kB on MIPS.

Signed-off-by: Jonas Gorski <jonas.gorski@gmail.com>

1 files changed, 69 insertions, 0 deletions

diff --git a/target/linux/generic/patches-4.4/087-regmap-make-LZO-cache-optional.patch b/target/linux/generic/patches-4.4/087-regmap-make-LZO-cache-optional.patch
new file mode 100644
index 0000000000..c26994ee35
--- /dev/null
+++ b/target/linux/generic/patches-4.4/087-regmap-make-LZO-cache-optional.patch
@@ -0,0 +1,69 @@
+From de88e9b0354c2e3ff8eae3f97afe43a34f5ed239 Mon Sep 17 00:00:00 2001
+From: Jonas Gorski <jonas.gorski@gmail.com>
+Date: Sat, 13 May 2017 13:03:21 +0200
+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@gmail.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(-)
+
+--- 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
+--- 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
+--- 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_REGCACHE_COMPRESSED)
+ 	&regcache_lzo_ops,
++#endif
+ 	&regcache_flat_ops,
+ };
+