Re: [PATCH v3 2/4] spi: spi-geni-qcom: Fail new xfers if xfer/cancel/abort pending

[Stephen Boyd]

Quoting Douglas Anderson (2020-12-17 14:29:12)
> If we got a timeout when trying to send an abort command then it means
> that we just got 3 timeouts in a row:
> 
> 1. The original timeout that caused handle_fifo_timeout() to be
>    called.
> 2. A one second timeout waiting for the cancel command to finish.
> 3. A one second timeout waiting for the abort command to finish.
> 
> SPI is clocked by the controller, so nothing (aside from a hardware
> fault or a totally broken sequencer) should be causing the actual
> commands to fail in hardware.  However, even though the hardware
> itself is not expected to fail (and it'd be hard to predict how we
> should handle things if it did), it's easy to hit the timeout case by
> simply blocking our interrupt handler from running for a long period
> of time.  Obviously the system is in pretty bad shape if a interrupt
> handler is blocked for > 2 seconds, but there are certainly bugs (even
> bugs in other unrelated drivers) that can make this happen.
> 
> Let's make things a bit more robust against this case.  If we fail to
> abort we'll set a flag and then we'll block all future transfers until
> we have no more interrupts pending.
> 
> Fixes: 561de45f72bd ("spi: spi-geni-qcom: Add SPI driver support for GENI based QUP")
> Signed-off-by: Douglas Anderson <dianders@xxxxxxxxxxxx>
> ---

Reviewed-by: Stephen Boyd <swboyd@xxxxxxxxxxxx>