1. 15 Dec, 2020 16 commits
  2. 12 Dec, 2020 1 commit
    • Douglas Anderson's avatar
      irqchip/qcom-pdc: Fix phantom irq when changing between rising/falling · 2f5fbc43
      Douglas Anderson authored
      We have a problem if we use gpio-keys and configure wakeups such that
      we only want one edge to wake us up.  AKA:
        wakeup-event-action = <EV_ACT_DEASSERTED>;
        wakeup-source;
      
      Specifically we end up with a phantom interrupt that blocks suspend if
      the line was already high and we want wakeups on rising edges (AKA we
      want the GPIO to go low and then high again before we wake up).  The
      opposite is also problematic.
      
      Specifically, here's what's happening today:
      1. Normally, gpio-keys configures to look for both edges.  Due to the
         current workaround introduced in commit c3c0c2e1 ("pinctrl:
         qcom: Handle broken/missing PDC dual edge IRQs on sc7180"), if the
         line was high we'd configure for falling edges.
      2. At suspend time, we change to look for rising edges.
      3. After qcom_pdc_gic_set_type() runs, we get a phantom interrupt.
      
      We can solve this by just clearing the phantom interrupt.
      
      NOTE: it is possible that this could cause problems for a client with
      very specific needs, but there's not much we can do with this
      hardware.  As an example, let's say the interrupt signal is currently
      high and the client is looking for falling edges.  The client now
      changes to look for rising edges.  The client could possibly expect
      that if the line has a short pulse low (and back high) that it would
      always be detected.  Specifically no matter when the pulse happened,
      it should either have tripped the (old) falling edge trigger or the
      (new) rising edge trigger.  We will simply not trip it.  We could
      narrow down the race a bit by polling our parent before changing
      types, but no matter what we do there will still be a period of time
      where we can't tell the difference between a real transition (or more
      than one transition) and the phantom.
      
      Fixes: f55c73ae ("irqchip/pdc: Add PDC interrupt controller for QCOM SoCs")
      Signed-off-by: default avatarDouglas Anderson <dianders@chromium.org>
      Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
      Tested-by: default avatarMaulik Shah <mkshah@codeaurora.org>
      Reviewed-by: default avatarMaulik Shah <mkshah@codeaurora.org>
      Reviewed-by: default avatarStephen Boyd <swboyd@chromium.org>
      Link: https://lore.kernel.org/r/20201211141514.v4.1.I2702919afc253e2a451bebc3b701b462b2d22344@changeid
      2f5fbc43
  3. 11 Dec, 2020 23 commits