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authorH. Nikolaus Schaller <hns@goldelico.com>2019-06-04 14:35:58 +0200
committerLinus Walleij <linus.walleij@linaro.org>2019-06-08 00:03:18 +0200
commit3b00691cc46a4089368a008b30655a8343411715 (patch)
tree8dfdd0941d277e7a9ec9480029d8343c2b8da710 /drivers/gpio
parentf2c7c76c5d0a443053e94adb9f0918fa2fb85c3a (diff)
gpio: pca953x: hack to fix 24 bit gpio expanders
24 bit expanders use REG_ADDR_AI in combination with register addressing. This conflicts with regmap which takes this bit as part of the register number, i.e. a second cache entry is defined for accessed with REG_ADDR_AI being set although on the chip it is the same register as with REG_ADDR_AI being cleared. The problem was introduced by commit b32cecb46bdc ("gpio: pca953x: Extract the register address mangling to single function") but only became visible by commit 8b9f9d4dc511 ("regmap: verify if register is writeable before writing operations") because before, the regmap size was effectively ignored and pca953x_writeable_register() did know to ignore REG_ADDR_AI. Still, there were two separate cache entries created. Since the use of REG_ADDR_AI seems to be static we can work around this issue by simply increasing the size of the regmap to cover the "virtual" registers with REG_ADDR_AI being set. This only means that half of the regmap buffer will be unused. Reported-by: H. Nikolaus Schaller <hns@goldelico.com> Suggested-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Diffstat (limited to 'drivers/gpio')
-rw-r--r--drivers/gpio/gpio-pca953x.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/gpio/gpio-pca953x.c b/drivers/gpio/gpio-pca953x.c
index b7ef33f63392..2b27d18410aa 100644
--- a/drivers/gpio/gpio-pca953x.c
+++ b/drivers/gpio/gpio-pca953x.c
@@ -308,7 +308,8 @@ static const struct regmap_config pca953x_i2c_regmap = {
.volatile_reg = pca953x_volatile_register,
.cache_type = REGCACHE_RBTREE,
- .max_register = 0x7f,
+ /* REVISIT: should be 0x7f but some 24 bit chips use REG_ADDR_AI */
+ .max_register = 0xff,
};
static u8 pca953x_recalc_addr(struct pca953x_chip *chip, int reg, int off,