[PATCH] mmc: dw_mmc: Don't send clock off command if power is off

Doug Anderson dianders at chromium.org
Sun Mar 22 14:59:27 PDT 2015


On Sun, Mar 22, 2015 at 5:16 AM, Alim Akhtar <alim.akhtar at gmail.com> wrote:
>>         case MMC_POWER_OFF:
>> -               /* Turn clock off before power goes down */
>> -               dw_mci_setup_bus(slot, false);
>> +               /* Turn clock off before power goes down; only if powered */
>> +               if (slot->host->vqmmc_enabled)
>> +                       dw_mci_setup_bus(slot, false);
> vqmmc_enabled is always _true_ when entering MMC_POWER_OFF case..right?
> Is this done for extra protection? Or do you have a case where vqmmc
> is OFF and driver still calls dw_mci_setup_bus from here?

Hmm.  I know I got it into the debugger in at least one reboot case
where it was failing to turn the clock off.  I thought I confirmed it
was the core trying to call MMC_POWER_OFF when the power was already
off, but now I'm less certain.  I looked back at my debug session and
I don't see where I got that evidence.  :-/  Certainly if I put a
printout here right now I can't see my code making a difference.

Unfortunately the crash was a very rare one, so I may have to go back
to the drawing board here...


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