GPIO fix for v4.15: fix a raw vs elaborate GPIO descriptor bug
introduced by yours truly.
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gpio: Add missing open drain/source handling to gpiod_set_value_cansleep()

Since commit f11a04464ae57e8d ("i2c: gpio: Enable working over slow
can_sleep GPIOs"), probing the i2c RTC connected to an i2c-gpio bus on
r8a7740/armadillo fails with:

    rtc-s35390a 0-0030: error resetting chip
    rtc-s35390a: probe of 0-0030 failed with error -5

More debug code reveals:

    i2c i2c-0: master_xfer[0] R, addr=0x30, len=1
    i2c i2c-0: NAK from device addr 0x30 msg #0
    s35390a_get_reg: ret = -6

Commit 02e479808b5d62f8 ("gpio: Alter semantics of *raw* operations to
actually be raw") moved open drain/source handling from
gpiod_set_raw_value_commit() to gpiod_set_value(), but forgot to take
into account that gpiod_set_value_cansleep() also needs this handling.
The i2c protocol mandates that i2c signals are open drain, hence i2c
communication fails.

Fix this by adding the missing handling to gpiod_set_value_cansleep(),
using a new common helper gpiod_set_value_nocheck().

Fixes: 02e479808b5d62f8 ("gpio: Alter semantics of *raw* operations to actually be raw")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
[removed underscore syntax, added kerneldoc]
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
1 file changed