Quoting Douglas Anderson (2020-12-17 14:29:13) > If we get a timeout sending then this happens: > > spi_transfer_one_message() > ->transfer_one() AKA spi_geni_transfer_one() > setup_fifo_xfer() > mas->cur_xfer = non-NULL > spi_transfer_wait() => TIMES OUT > if (msg->status != -EINPROGRESS) > goto out > if (ret != 0 ...) > spi_set_cs() > ->set_cs AKA spi_geni_set_cs() > # mas->cur_xfer is non-NULL > > The above happens _before_ the SPI core calls ->handle_err() AKA > handle_fifo_timeout(). > > Unfortunately that won't work so well on geni. If we got a timeout > transferring then it's likely that our interrupt handler is blocked, > but we need that same interrupt handler to run and the command channel > to be unblocked in order to adjust the chip select. Trying to set the > chip select doesn't crash us but ends up confusing our state machine > and leads to messages like: Premature done. rx_rem = 32 bpw8 > > Let's just drop the chip select request in this case. We can detect > the case because cur_xfer is non-NULL--it would have been set to NULL > in the interrupt handler if the previous transfer had finished. Sure, > we might leave the chip select in the wrong state but it's likely it > was going to fail anyway and this avoids getting the driver even more > confused about what it's doing. > > The SPI core in general assumes that setting chip select is a simple > operation that doesn't fail. Yet another reason to just reconfigure > the chip select line as GPIOs. > > Signed-off-by: Douglas Anderson <dianders@xxxxxxxxxxxx> > --- Reviewed-by: Stephen Boyd <swboyd@xxxxxxxxxxxx>
