From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jaehoon Chung Subject: Re: [PATCH] RFC: mmc: dw_mmc: Always go to STATE_DATA_BUSY from STATE_DATA_ERROR Date: Mon, 18 Mar 2013 19:21:36 +0900 Message-ID: <5146EAB0.1030705@samsung.com> References: <1363382956-14557-1-git-send-email-dianders@chromium.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from mailout3.samsung.com ([203.254.224.33]:28328 "EHLO mailout3.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752356Ab3CRKVf (ORCPT ); Mon, 18 Mar 2013 06:21:35 -0400 In-reply-to: <1363382956-14557-1-git-send-email-dianders@chromium.org> Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: Doug Anderson Cc: Chris Ball , Will Newton , Seungwon Jeon , Bing Zhao , Jaehoon Chung , Ashok Nagarajan , Paul Stewart , Olof Johansson , linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org Hi Doug, Great..i have found the problem like this. I will check your patch..and share the result. Best Regards, Jaehoon Chung On 03/16/2013 06:29 AM, Doug Anderson wrote: > 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 > Signed-off-by: Doug Anderson > --- > 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; > } >