• Alek Du's avatar
    mmc: sdhci: fix the timeout check window for clock and reset · 38ef9c5a
    Alek Du authored
    commit b704441e upstream.
    
    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: default avatarAlek Du <alek.du@intel.com>
    Acked-by: default avatarAdrian Hunter <adrian.hunter@intel.com>
    Signed-off-by: default avatarUlf Hansson <ulf.hansson@linaro.org>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    38ef9c5a
sdhci.c 106 KB