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