On Wed, May 21, 2014, Doug Anderson wrote: > If we happened to get a data error at just the wrong time the dw_mmc > driver could get into a state where it would never complete its > request. That would leave the caller just hanging there. > > We fix this two ways and both of the two fixes on their own appear to > fix the problems we've seen: > > 1. Fix a race in the tasklet where the interrupt setting the data > error happens _just after_ we check for it, then we get a > EVENT_XFER_COMPLETE. We fix this by repeating a bit of code. > 2. Fix it so that if we detect that we've got an error in the "data > busy" state and we're not going to do anything else we end the > request and unblock anyone waiting. > > Signed-off-by: Doug Anderson <[email protected]> > Signed-off-by: Yuvaraj Kumar C D <[email protected]>
It will be applied after "mmc: dw_mmc: change to use recommended reset procedure" Acked-by: Seungwon Jeon <[email protected]> Thanks, Seungwon Jeon > --- > Changes in v2: > - Removed TODO > - Set cmd to NULL before calling dw_mci_request_end() > > drivers/mmc/host/dw_mmc.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 46 insertions(+) > > diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c > index cced599..54ec8b0 100644 > --- a/drivers/mmc/host/dw_mmc.c > +++ b/drivers/mmc/host/dw_mmc.c > @@ -1318,6 +1318,14 @@ static void dw_mci_tasklet_func(unsigned long priv) > /* fall through */ > > case STATE_SENDING_DATA: > + /* > + * We could get a data error and never a transfer > + * complete so we'd better check for it here. > + * > + * Note that we don't really care if we also got a > + * transfer complete; stopping the DMA and sending an > + * abort won't hurt. > + */ > if (test_and_clear_bit(EVENT_DATA_ERROR, > &host->pending_events)) { > dw_mci_stop_dma(host); > @@ -1331,7 +1339,29 @@ static void dw_mci_tasklet_func(unsigned long priv) > break; > > set_bit(EVENT_XFER_COMPLETE, &host->completed_events); > + > + /* > + * Handle an EVENT_DATA_ERROR that might have shown up > + * before the transfer completed. This might not have > + * been caught by the check above because the interrupt > + * could have gone off between the previous check and > + * the check for transfer complete. > + * > + * Technically this ought not be needed assuming we > + * get a DATA_COMPLETE eventually (we'll notice the > + * error and end the request), but it shouldn't hurt. > + * > + * This has the advantage of sending the stop command. > + */ > + if (test_and_clear_bit(EVENT_DATA_ERROR, > + &host->pending_events)) { > + dw_mci_stop_dma(host); > + send_stop_abort(host, data); > + state = STATE_DATA_ERROR; > + break; > + } > prev_state = state = STATE_DATA_BUSY; > + > /* fall through */ > > case STATE_DATA_BUSY: > @@ -1354,6 +1384,22 @@ static void dw_mci_tasklet_func(unsigned long priv) > /* stop command for open-ended transfer*/ > if (data->stop) > send_stop_abort(host, data); > + } else { > + /* > + * If we don't have a command complete now we'll > + * never get one since we just reset everything; > + * better end the request. > + * > + * If we do have a command complete we'll fall > + * through to the SENDING_STOP command and > + * everything will be peachy keen. > + */ > + if (!test_bit(EVENT_CMD_COMPLETE, > + &host->pending_events)) { > + host->cmd = NULL; > + dw_mci_request_end(host, mrq); > + goto unlock; > + } > } > > /* > -- > 1.9.1.423.g4596e3a > > -- > To unsubscribe from this list: send the line "unsubscribe linux-mmc" in > the body of a message to [email protected] > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
