1. 17 Sep, 2018 13 commits
  2. 14 Sep, 2018 1 commit
  3. 13 Sep, 2018 2 commits
    • Uwe Kleine-König's avatar
      gpiolib: Don't support irq sharing for userspace · fa38869b
      Uwe Kleine-König authored
      This concerns gpio edge detection for GPIO IRQs used from
      userspace for GPIO event listeners.
      
      Trying to work out the right event if it's not sure that the
      examined gpio actually moved is impossible.
      
      Consider two gpios "gpioA" and "gpioB" that share an interrupt.
      gpioA's irq should trigger on any edge, gpioB's on a falling edge.
      If now the common irq fires and both gpio lines are high, there
      are several possibilities that could have happend:
      
       a) gpioA just had a low-to-high edge
       b) gpioB just had a high-to-low-to-high spike
       c) a combination of both a) and b)
      
      While c) is unlikely (in most setups) a) and b) alone are bad
      enough. Currently the code assumes case a) unconditionally and
      doesn't report an event for gpioB. Note that even if there is no
      irq sharing involved a spike for a gpio might not result in an
      event if it's configured to trigger for a single edge only.
      
      The only way to improve this is to drop support for interrupt
      sharing. This way a spike results in an event for the right gpio
      at least. Note that apart from dropping IRQF_SHARED this
      effectively undoes commit df1e76f2
      ("gpiolib: skip unwanted events, don't convert them to opposite edge").
      
      This obviously breaks setups that rely on interrupt sharing,
      but given that this cannot be reliable, this is probably an
      acceptable trade-off.
      Signed-off-by: default avatarUwe Kleine-König <u.kleine-koenig@pengutronix.de>
      [Assuming there are no users of interrupt sharing yet]
      Signed-off-by: default avatarLinus Walleij <linus.walleij@linaro.org>
      fa38869b
    • Geert Uytterhoeven's avatar
  4. 12 Sep, 2018 2 commits
  5. 11 Sep, 2018 2 commits
  6. 10 Sep, 2018 16 commits
  7. 04 Sep, 2018 4 commits