Commit b704441e authored by Alek Du's avatar Alek Du Committed by Ulf Hansson
Browse files

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

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:      # v4.12+
Signed-off-by: default avatarAlek Du <>
Acked-by: default avatarAdrian Hunter <>
Signed-off-by: default avatarUlf Hansson <>
parent db2039fc
......@@ -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))
if (timedout) {
pr_err("%s: Reset 0x%x never completed.\n",
mmc_hostname(host->mmc), (int)mask);
......@@ -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))
if (ktime_after(ktime_get(), timeout)) {
while (1) {
bool timedout = ktime_after(ktime_get(), timeout);
clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
if (timedout) {
pr_err("%s: Internal clock never stabilised.\n",
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