Hi Chris & Ulf, I hope you find this patch for next.
Thanks, Seungwon Jeon On Wed, May 21, 2014, Seungwon Jeon wrote: > 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-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/
