On Thu, 6 Dec 2018 at 10:25, alek.du@intel.com wrote:
From: Alek Du alek.du@intel.com
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: 5a436cc0af62 ("mmc: sdhci: Optimize delay loops") Cc: stable@vger.kernel.org # v4.12+ Signed-off-by: Alek Du alek.du@intel.com
Yes, now it works better!
Applied for fixes and by adding Adrian's ack, thanks!
Kind regards Uffe
drivers/mmc/host/sdhci.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-)
diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c index 99bdae53fa2e..451b08a818a9 100644 --- a/drivers/mmc/host/sdhci.c +++ b/drivers/mmc/host/sdhci.c @@ -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);-- 2.17.1