From: Phil Elwell <p...@raspberrypi.org> [ Upstream commit 07d405769afea5718529fc9e341f0b13b3189b6f ]
If the user issues an "mmc extcsd read", the SD controller receives what it thinks is a SEND_IF_COND command with an unexpected data block. The resulting operations leave the FSM stuck in READWAIT, a state which persists until the MMC framework resets the controller, by which point the root filesystem is likely to have been unmounted. A less heavyweight solution is to detect the condition and nudge the FSM by asserting the (self-clearing) FORCE_DATA_MODE bit. Link: https://github.com/raspberrypi/linux/issues/2728 Signed-off-by: Phil Elwell <p...@raspberrypi.org> Signed-off-by: Stefan Wahren <stefan.wah...@i2se.com> Acked-by: Eric Anholt <e...@anholt.net> Signed-off-by: Ulf Hansson <ulf.hans...@linaro.org> Signed-off-by: Sasha Levin <sas...@kernel.org> --- drivers/mmc/host/bcm2835.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/mmc/host/bcm2835.c b/drivers/mmc/host/bcm2835.c index 768972af8b85..aef40e1739ee 100644 --- a/drivers/mmc/host/bcm2835.c +++ b/drivers/mmc/host/bcm2835.c @@ -772,6 +772,8 @@ static void bcm2835_finish_command(struct bcm2835_host *host) if (!(sdhsts & SDHSTS_CRC7_ERROR) || (host->cmd->opcode != MMC_SEND_OP_COND)) { + u32 edm, fsm; + if (sdhsts & SDHSTS_CMD_TIME_OUT) { host->cmd->error = -ETIMEDOUT; } else { @@ -780,6 +782,13 @@ static void bcm2835_finish_command(struct bcm2835_host *host) bcm2835_dumpregs(host); host->cmd->error = -EILSEQ; } + edm = readl(host->ioaddr + SDEDM); + fsm = edm & SDEDM_FSM_MASK; + if (fsm == SDEDM_FSM_READWAIT || + fsm == SDEDM_FSM_WRITESTART1) + /* Kick the FSM out of its wait */ + writel(edm | SDEDM_FORCE_DATA_MODE, + host->ioaddr + SDEDM); bcm2835_finish_request(host); return; } -- 2.19.1
