On a flaky piece of hardware that seems good at generating CRC errors, we have found that often times the CRC errors don't get reported properly when using CONFIG_MMC_DW_IDMAC (they get reported OK when using pio). The flow that happens is: 1. dw_mci_interrupt() fires and status=80b8, pending=8088 so that we hit (pending & DW_MCI_DATA_ERROR_FLAGS). We store 8088 in data_status and set EVENT_DATA_ERROR in host->pending_events 2. We schedule the tasklet and it runs. 3. We're in STATE_SENDING_DATA in the tasklet and see EVENT_DATA_ERROR so we dw_mci_stop_dma(). 4. dw_mci_stop_dma() calls dw_mci_idmac_stop_dma() and dw_mci_dma_cleanup(). These stop dma but _don't_ set EVENT_XFER_COMPLETE (since we're host->using_dma). 5. data->stop is NULL so we don't send a stop command. 6. We move onto STATE_DATA_ERROR and loop again in the tasklet. 7. We hit STATE_DATA_ERROR but the transfer isn't done, so the tasklet stops. We never seem to get any additional DMA interrupts that cause EVENT_XFER_COMPLETE and restart the tasklet so we just hang. That doesn't seem surprising given that we've stopped DMA. We did put a print at the end of dw_mci_interrupt() to show the result of the "mci_readl(host, IDSTS)" and saw 0xa000 in the case of the above CRC error. A proposed fix for this is to ignore (but still clear) the EVENT_XFER_COMPLETE in STATE_DATA_ERROR in the tasklet. Reported-by: Bing Zhao <bzhao@xxxxxxxxxxx> Signed-off-by: Doug Anderson <dianders@xxxxxxxxxxxx> --- drivers/mmc/host/dw_mmc.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c index 9834221..696b3bb 100644 --- a/drivers/mmc/host/dw_mmc.c +++ b/drivers/mmc/host/dw_mmc.c @@ -1137,10 +1137,7 @@ static void dw_mci_tasklet_func(unsigned long priv) goto unlock; case STATE_DATA_ERROR: - if (!test_and_clear_bit(EVENT_XFER_COMPLETE, - &host->pending_events)) - break; - + clear_bit(EVENT_XFER_COMPLETE, &host->pending_events); state = STATE_DATA_BUSY; break; } -- 1.8.1.3 -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
