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 commitb32cecb46b
("gpio: pca953x: Extract the register address mangling to single function") but only became visible by commit8b9f9d4dc5
("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>
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@ -308,7 +308,8 @@ static const struct regmap_config pca953x_i2c_regmap = {
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.volatile_reg = pca953x_volatile_register,
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.cache_type = REGCACHE_RBTREE,
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.max_register = 0x7f,
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/* REVISIT: should be 0x7f but some 24 bit chips use REG_ADDR_AI */
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.max_register = 0xff,
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};
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static u8 pca953x_recalc_addr(struct pca953x_chip *chip, int reg, int off,
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