2019-09-19 14:43:19 +00:00
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From 5010dba0e3f6f2c9d623e265276d9b6993fa96b0 Mon Sep 17 00:00:00 2001
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2019-07-09 18:32:28 +00:00
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From: Phil Elwell <phil@raspberrypi.org>
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Date: Fri, 26 Oct 2018 17:29:51 +0100
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2019-09-19 14:43:19 +00:00
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Subject: [PATCH 179/806] mmc/bcm2835-sdhost: Recover from MMC_SEND_EXT_CSD
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2019-07-09 18:32:28 +00:00
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If the user issues an "mmc extcsd read", the SD controller receives
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what it thinks is a SEND_IF_COND command with an unexpected data block.
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The resulting operations leave the FSM stuck in READWAIT, a state which
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persists until the MMC framework resets the controller, by which point
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the root filesystem is likely to have been unmounted.
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A less heavyweight solution is to detect the condition and nudge the
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FSM by asserting the (self-clearing) FORCE_DATA_MODE bit.
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N.B. This workaround was essentially discovered by accident and without
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a full understanding the inner workings of the controller, so it is
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fortunate that the "fix" only modifies error paths.
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See: https://github.com/raspberrypi/linux/issues/2728
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Signed-off-by: Phil Elwell <phil@raspberrypi.org>
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---
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drivers/mmc/host/bcm2835-sdhost.c | 9 +++++++++
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1 file changed, 9 insertions(+)
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--- a/drivers/mmc/host/bcm2835-sdhost.c
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+++ b/drivers/mmc/host/bcm2835-sdhost.c
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@@ -1244,6 +1244,8 @@ static void bcm2835_sdhost_finish_comman
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pr_info("%s: ignoring CRC7 error for CMD1\n",
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mmc_hostname(host->mmc));
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} else {
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+ u32 edm, fsm;
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+
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if (sdhsts & SDHSTS_CMD_TIME_OUT) {
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if (host->debug)
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pr_warn("%s: command %d timeout\n",
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@@ -1256,6 +1258,13 @@ static void bcm2835_sdhost_finish_comman
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host->cmd->opcode);
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host->cmd->error = -EILSEQ;
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}
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+
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+ edm = readl(host->ioaddr + SDEDM);
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+ fsm = edm & SDEDM_FSM_MASK;
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+ if (fsm == SDEDM_FSM_READWAIT ||
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+ fsm == SDEDM_FSM_WRITESTART1)
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+ writel(edm | SDEDM_FORCE_DATA_MODE,
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+ host->ioaddr + SDEDM);
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tasklet_schedule(&host->finish_tasklet);
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return;
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}
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