4.20-stable review patch. If anyone has any objections, please let me know.
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[ 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 phil@raspberrypi.org Signed-off-by: Stefan Wahren stefan.wahren@i2se.com Acked-by: Eric Anholt eric@anholt.net Signed-off-by: Ulf Hansson ulf.hansson@linaro.org Signed-off-by: Sasha Levin sashal@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 0d3b7473bc21..abf1f3c8b0c3 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; }