From: Phil Elwell <phil@xxxxxxxxxxxxxxx> 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 <phil@xxxxxxxxxxxxxxx> --- 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 f1712df..a251be2 100644 --- a/drivers/mmc/host/bcm2835.c +++ b/drivers/mmc/host/bcm2835.c @@ -773,6 +773,8 @@ 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 { @@ -781,6 +783,13 @@ 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; } -- 2.7.4
