Commit b704441e authored Dec 06, 2018 by Alek Du Committed by Ulf Hansson Dec 06, 2018

mmc: sdhci: fix the timeout check window for clock and reset



We observed some premature timeouts on a virtualization platform, the log
is like this:

case 1:
[159525.255629] mmc1: Internal clock never stabilised.
[159525.255818] mmc1: sdhci: ============ SDHCI REGISTER DUMP ===========
[159525.256049] mmc1: sdhci: Sys addr:  0x00000000 | Version:  0x00001002
...
[159525.257205] mmc1: sdhci: Wake-up:   0x00000000 | Clock:    0x0000fa03
From the clock control register dump, we are pretty sure the clock was
stablized.

case 2:
[  914.550127] mmc1: Reset 0x2 never completed.
[  914.550321] mmc1: sdhci: ============ SDHCI REGISTER DUMP ===========
[  914.550608] mmc1: sdhci: Sys addr:  0x00000010 | Version:  0x00001002

After checking the sdhci code, we found the timeout check actually has a
little window that the CPU can be scheduled out and when it comes back,
the original time set or check is not valid.

Fixes: 5a436cc0 ("mmc: sdhci: Optimize delay loops")
Cc: stable@vger.kernel.org      # v4.12+
Signed-off-by: Alek Du <alek.du@intel.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

parent db2039fc

drivers/mmc/host/sdhci.c

+13 −5

Original line number	Diff line number	Diff line
		@@ -216,8 +216,12 @@ void sdhci_reset(struct sdhci_host *host, u8 mask)
		timeout = ktime_add_ms(ktime_get(), 100);

		/* hw clears the bit when it's done */
		while (sdhci_readb(host, SDHCI_SOFTWARE_RESET) & mask) {
		if (ktime_after(ktime_get(), timeout)) {
		while (1) {
		bool timedout = ktime_after(ktime_get(), timeout);

		if (!(sdhci_readb(host, SDHCI_SOFTWARE_RESET) & mask))
		break;
		if (timedout) {
		pr_err("%s: Reset 0x%x never completed.\n",
		mmc_hostname(host->mmc), (int)mask);
		sdhci_dumpregs(host);
		@@ -1608,9 +1612,13 @@ void sdhci_enable_clk(struct sdhci_host *host, u16 clk)

		/* Wait max 20 ms */
		timeout = ktime_add_ms(ktime_get(), 20);
		while (!((clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL))
		& SDHCI_CLOCK_INT_STABLE)) {
		if (ktime_after(ktime_get(), timeout)) {
		while (1) {
		bool timedout = ktime_after(ktime_get(), timeout);

		clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
		if (clk & SDHCI_CLOCK_INT_STABLE)
		break;
		if (timedout) {
		pr_err("%s: Internal clock never stabilised.\n",
		mmc_hostname(host->mmc));
		sdhci_dumpregs(host);

Admin message