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| author | H. Nikolaus Schaller <hns@goldelico.com> | 2019-06-04 14:35:58 +0200 |
|---|---|---|
| committer | Linus Walleij <linus.walleij@linaro.org> | 2019-06-08 00:03:18 +0200 |
| commit | 3b00691cc46a4089368a008b30655a8343411715 (patch) | |
| tree | 8dfdd0941d277e7a9ec9480029d8343c2b8da710 /drivers/gpio/gpio-pca953x.c | |
| parent | Linux 5.2-rc3 (diff) | |
| download | linux-3b00691cc46a4089368a008b30655a8343411715.tar.xz linux-3b00691cc46a4089368a008b30655a8343411715.zip | |
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/gpio-pca953x.c')
| -rw-r--r-- | drivers/gpio/gpio-pca953x.c | 3 |
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, |