| Message ID | 1407942823-4271-1-git-send-email-dianders@chromium.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 13 August 2014 17:13, Doug Anderson <dianders@chromium.org> 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 <dianders@chromium.org> > Signed-off-by: Yuvaraj Kumar C D <yuvaraj.cd@gmail.com> > Acked-by: Seungwon Jeon <tgih.jun@samsung.com> Thanks! Applied for next. Kind regards Uffe > --- > 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 8f216ed..7f227e9 100644 > --- a/drivers/mmc/host/dw_mmc.c > +++ b/drivers/mmc/host/dw_mmc.c > @@ -1299,6 +1299,14 @@ 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); > @@ -1312,7 +1320,29 @@ 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: > @@ -1335,6 +1365,22 @@ 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; > + } > } > > /* > -- > 2.1.0.rc2.206.gedb03e5 > -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c index 8f216ed..7f227e9 100644 --- a/drivers/mmc/host/dw_mmc.c +++ b/drivers/mmc/host/dw_mmc.c @@ -1299,6 +1299,14 @@ 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); @@ -1312,7 +1320,29 @@ 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: @@ -1335,6 +1365,22 @@ 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; + } } /*