Hi, On Thu, Jun 18, 2020 at 2:52 PM Stephen Boyd <swboyd@xxxxxxxxxxxx> wrote: > > Quoting Doug Anderson (2020-06-18 13:09:47) > > On Thu, Jun 18, 2020 at 11:05 AM Stephen Boyd <swboyd@xxxxxxxxxxxx> wrote: > > > > > > Quoting Douglas Anderson (2020-06-18 08:06:26) > > > > @@ -126,20 +120,23 @@ static void handle_fifo_timeout(struct spi_master *spi, > > > > struct geni_se *se = &mas->se; > > > > > > > > spin_lock_irq(&mas->lock); > > > > - reinit_completion(&mas->xfer_done); > > > > - mas->cur_mcmd = CMD_CANCEL; > > > > - geni_se_cancel_m_cmd(se); > > > > + reinit_completion(&mas->cancel_done); > > > > writel(0, se->base + SE_GENI_TX_WATERMARK_REG); > > > > + mas->cur_xfer = NULL; > > > > > > BTW, is this necessary? It's subtlely placed here without a comment why. > > > > I believe so. Now that we don't have the "cur_mcmd" we rely on > > cur_xfer being NULL to tell the difference between a "done" for chip > > select vs. a "done" for transfer. > > > > * When we start a transfer we set "cur_xfer" to a non-NULL pointer. > > When the transfer finishes we set it to NULL again. > > > > * When we start a chip select transfer we _don't_ explicitly set it to > > NULL because it should already be NULL. > > > > * When we are aborting a transfer we need to NULL so we can handle the > > chip select that will come next. > > > > I suppose it's possible that we could get by without without NULLing > > it because I believe when the "abort" IRQ finally fires then it will > > include a "DONE" and that would presumably NULL it out. ...but I > > guess if both the cancel and abort timed out and no IRQ ever fired > > then nothing would have NULLed it and the next chip select would be > > confused. > > I was going to say that we should set it NULL when starting CS but that > is not as important as clearing it out when a cancel/abort is processing > so that a stale transfer isn't kept around. > > > > > Prior to getting rid of "cur_mcmd" this all wasn't needed because > > "cur_xfer" was only ever looked at if "cur_mcmd" was set to > > "CMD_XFER". > > > > > > One part of my change that is technically not related to the removal > > of "cur_mcmd" is the part where I do "mas->tx_rem_bytes = > > mas->rx_rem_bytes = 0;". I can split that as a separate change if you > > want but it seemed fine to just clean up this extra bit of state here. > > > > How about a comment like this? > > -----8<---- > diff --git a/drivers/spi/spi-geni-qcom.c b/drivers/spi/spi-geni-qcom.c > index d8f03ffb8594..670f83793aa4 100644 > --- a/drivers/spi/spi-geni-qcom.c > +++ b/drivers/spi/spi-geni-qcom.c > @@ -121,6 +121,10 @@ static void handle_fifo_timeout(struct spi_master *spi, > spin_lock_irq(&mas->lock); > reinit_completion(&mas->cancel_done); > writel(0, se->base + SE_GENI_TX_WATERMARK_REG); > + /* > + * Make sure we don't finalize a spi transfer that timed out but > + * came in while cancelling. > + */ > mas->cur_xfer = NULL; > mas->tx_rem_bytes = mas->rx_rem_bytes = 0; > geni_se_cancel_m_cmd(se); Sure. It gets the point across, though spi_finalize_current_transfer() is actually pretty harmless if you call it while cancelling. It just calls a completion. I'd rather say something like "If we're here because the SPI controller was calling handle_err() then the transfer is done and we shouldn't hold onto it anymore". -Doug
