mmc: cqhci: Avoid false "cqhci: CQE stuck on" by not open-coding timeout loop (b1ac62a7) · Commits · 戴 / test

Open-coding a timeout loop invariably leads to errors with handling the timeout properly in one corner case or another. In the case of cqhci we might report "CQE stuck on" even if it wasn't stuck on. You'd just need this sequence of events to happen in cqhci_off(): 1. Call ktime_get(). 2. Something happens to interrupt the CPU for > 100 us (context switch or interrupt). 3. Check time and; set "timed_out" to true since > 100 us. 4. Read CQHCI_CTL. 5. Both "reg & CQHCI_HALT" and "timed_out" are true, so break. 6. Since "timed_out" is true, falsely print the error message. Rather than fixing the polling loop, use readx_poll_timeout() like many people do. This has been time tested to handle the corner cases. Fixes: ("mmc: cqhci: support for command queue enabled host") Signed-off-by:

Douglas Anderson <dianders@chromium.org> Acked-by:

Adrian Hunter <adrian.hunter@intel.com> Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20200413162717.1.Idece266f5c8793193b57a1ddb1066d030c6af8e0@changeid Signed-off-by:

Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/cqhci.c

+10 −11

Original line number	Diff line number	Diff line
		@@ -5,6 +5,7 @@
		#include <linux/delay.h>
		#include <linux/highmem.h>
		#include <linux/io.h>
		#include <linux/iopoll.h>
		#include <linux/module.h>
		#include <linux/dma-mapping.h>
		#include <linux/slab.h>
		@@ -349,12 +350,16 @@ static int cqhci_enable(struct mmc_host mmc, struct mmc_card card)
		/* CQHCI is idle and should halt immediately, so set a small timeout */
		#define CQHCI_OFF_TIMEOUT 100

		static u32 cqhci_read_ctl(struct cqhci_host *cq_host)
		{
		return cqhci_readl(cq_host, CQHCI_CTL);
		}

		static void cqhci_off(struct mmc_host *mmc)
		{
		struct cqhci_host *cq_host = mmc->cqe_private;
		ktime_t timeout;
		bool timed_out;
		u32 reg;
		int err;

		if (!cq_host->enabled \|\| !mmc->cqe_on \|\| cq_host->recovery_halt)
		return;
		@@ -364,15 +369,9 @@ static void cqhci_off(struct mmc_host *mmc)

		cqhci_writel(cq_host, CQHCI_HALT, CQHCI_CTL);

		timeout = ktime_add_us(ktime_get(), CQHCI_OFF_TIMEOUT);
		while (1) {
		timed_out = ktime_compare(ktime_get(), timeout) > 0;
		reg = cqhci_readl(cq_host, CQHCI_CTL);
		if ((reg & CQHCI_HALT) \|\| timed_out)
		break;
		}

		if (timed_out)
		err = readx_poll_timeout(cqhci_read_ctl, cq_host, reg,
		reg & CQHCI_HALT, 0, CQHCI_OFF_TIMEOUT);
		if (err < 0)
		pr_err("%s: cqhci: CQE stuck on\n", mmc_hostname(mmc));
		else
		pr_debug("%s: cqhci: CQE off\n", mmc_hostname(mmc));

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