From 5010dba0e3f6f2c9d623e265276d9b6993fa96b0 Mon Sep 17 00:00:00 2001 From: Phil Elwell Date: Fri, 26 Oct 2018 17:29:51 +0100 Subject: [PATCH] mmc/bcm2835-sdhost: Recover from MMC_SEND_EXT_CSD 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. N.B. This workaround was essentially discovered by accident and without a full understanding the inner workings of the controller, so it is fortunate that the "fix" only modifies error paths. See: https://github.com/raspberrypi/linux/issues/2728 Signed-off-by: Phil Elwell --- drivers/mmc/host/bcm2835-sdhost.c | 9 +++++++++ 1 file changed, 9 insertions(+) --- a/drivers/mmc/host/bcm2835-sdhost.c +++ b/drivers/mmc/host/bcm2835-sdhost.c @@ -1244,6 +1244,8 @@ static void bcm2835_sdhost_finish_comman pr_info("%s: ignoring CRC7 error for CMD1\n", mmc_hostname(host->mmc)); } else { + u32 edm, fsm; + if (sdhsts & SDHSTS_CMD_TIME_OUT) { if (host->debug) pr_warn("%s: command %d timeout\n", @@ -1256,6 +1258,13 @@ static void bcm2835_sdhost_finish_comman host->cmd->opcode); host->cmd->error = -EILSEQ; } + + edm = readl(host->ioaddr + SDEDM); + fsm = edm & SDEDM_FSM_MASK; + if (fsm == SDEDM_FSM_READWAIT || + fsm == SDEDM_FSM_WRITESTART1) + writel(edm | SDEDM_FORCE_DATA_MODE, + host->ioaddr + SDEDM); tasklet_schedule(&host->finish_tasklet); return; }