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From c2eae29f6503cf29ac6a204c51132cfed33d203e Mon Sep 17 00:00:00 2001
From: Phil Elwell <phil@raspberrypi.org>
Date: Fri, 26 Oct 2018 17:40:44 +0100
Subject: [PATCH 434/454] mmc/bcm2835: 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 <phil@raspberrypi.org>
---
drivers/mmc/host/bcm2835.c | 9 +++++++++
1 file changed, 9 insertions(+)
--- a/drivers/mmc/host/bcm2835.c
+++ b/drivers/mmc/host/bcm2835.c
@@ -772,6 +772,8 @@ static void bcm2835_finish_command(struc
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(struc
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;
}
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