From 43809ebf74fb06467a0dd6133d390f71f36d5cb0 Mon Sep 17 00:00:00 2001 From: Douglas Anderson Date: Mon, 18 May 2015 08:53:22 -0700 Subject: [PATCH] UPSTREAM: mmc: dw_mmc: Wait for data transfer after response errors According to the DesignWare state machine description, after we get a "response error" or "response CRC error" we move into data transfer mode. That means that we don't necessarily need to special case trying to deal with the failure right away. We can wait until we are notified that the data transfer is complete (with or without errors) and then we can deal with the failure. It may sound strange to defer dealing with a command that we know will fail anyway, but this appears to fix a bug. During tuning (CMD19) on a specific card on an rk3288-based system, we found that we could get a "response CRC error". Sending the stop command after the "response CRC error" would then throw the system into a confused state causing all future tuning phases to report failure. When in the confused state, the controller would show these (hex codes are interrupt status register): CMD ERR: 0x00000046 (cmd=19) CMD ERR: 0x0000004e (cmd=12) DATA ERR: 0x00000208 DATA ERR: 0x0000020c CMD ERR: 0x00000104 (cmd=19) CMD ERR: 0x00000104 (cmd=12) DATA ERR: 0x00000208 DATA ERR: 0x0000020c ... ... It is inherently difficult to deal with the complexity of trying to correctly send a stop command while a data transfer is taking place since you need to deal with different corner cases caused by the fact that the data transfer could complete (with errors or without errors) during various places in sending the stop command (dw_mci_stop_dma, send_stop_abort, etc) Instead of adding a bunch of extra complexity to deal with this, it seems much simpler to just use the more straightforward (and less error-prone) path of letting the data transfer finish. There shouldn't be any huge benefit to sending the stop command slightly earlier, anyway. BUG=redmine:102457 (cherry picked from commit 46d179525a1f6d16957dcb4624517bc04142b3e7) Change-Id: I1356df95ea7851b2143ba48dc66310e203341721 Signed-off-by: Doug Anderson Signed-off-by: Ziyuan Xu --- drivers/mmc/host/dw_mmc.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c index a5cb75227d70..3f5ece5f9cc2 100644 --- a/drivers/mmc/host/dw_mmc.c +++ b/drivers/mmc/host/dw_mmc.c @@ -1766,6 +1766,26 @@ static void dw_mci_tasklet_func(unsigned long priv) } if (cmd->data && err) { + /* + * Controller will move into a data transfer + * state after a response error or response CRC + * error. Let's let that finish before trying + * to send a stop, so we'll go to + * STATE_SENDING_DATA. + * + * Although letting the data transfer take place + * will waste a bit of time (we already know + * the command was bad), it can't cause any + * errors since it's possible it would have + * taken place anyway if this tasklet got + * delayed. Allowing the transfer to take place + * avoids races and keeps things simple. + */ + if (err != -ETIMEDOUT) { + state = STATE_SENDING_DATA; + continue; + } + dw_mci_stop_dma(host); send_stop_abort(host, data); state = STATE_SENDING_STOP; -- 2.34.1