Hi Linus, On Wed, Jan 10, 2018 at 2:17 PM, Linus Walleij <linus.walleij@xxxxxxxxxx> wrote: > On Tue, Jan 9, 2018 at 7:08 PM, Geert Uytterhoeven > <geert+renesas@xxxxxxxxx> wrote: > >> 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@xxxxxxxxx> >> --- >> The bad gpio commit is in v4.15-rc1 and later. >> The i2c commit exposing this is not yet upstream, but in i2c/for-next. > > Whoops! > > It appears Meltdown and Spectre saves my ass because now I have > time to get this upstream before v4.15... > > Applied for fixes with the following tweaks: I removed the __prefix (I don't > like them) and added kerneldoc. Looks good to me (also in git). Thanks! Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds -- To unsubscribe from this list: send the line "unsubscribe linux-gpio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html