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  1. Jan 10, 2018
    • Geert Uytterhoeven's avatar
      gpio: Add missing open drain/source handling to gpiod_set_value_cansleep() · 1e77fc82
      Geert Uytterhoeven authored
      
      
      Since commit f11a0446 ("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 02e47980 ("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: 02e47980 ("gpio: Alter semantics of *raw* operations to actually be raw")
      Signed-off-by: default avatarGeert Uytterhoeven <geert+renesas@glider.be>
      [removed underscore syntax, added kerneldoc]
      Signed-off-by: default avatarLinus Walleij <linus.walleij@linaro.org>
      1e77fc82
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