On Thu, May 1, 2014 at 12:09 PM, Dan Williams <dan.j.williams@xxxxxxxxx> wrote:
> On Thu, May 1, 2014 at 12:02 PM, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote:
>> On Thu, 1 May 2014, Dan Williams wrote:
>>
>>> > @@ -122,6 +127,11 @@ static int usb_port_runtime_suspend(stru
>>> > == PM_QOS_FLAGS_ALL)
>>> > return -EAGAIN;
>>> >
>>> > + if (hub->in_reset) {
>>> > + port_dev->power_is_on = 0;
>>> > + return 0;
>>> > + }
>>>
>>> Why lie? Just return -EBUSY and be done.
>>
>> Good idea; the complete, updated patch is below. (It's against
>> 3.15-rc2, without any of your RFC changes.)
>>
>>> In fact that also has the
>>> nice side effect of clearing runtime errors it seems.
>>
>> Not really, because if there was an earlier runtime PM error then
>> dev->power.runtime_error would be set, so rpm_check_suspend_allowed()
>> would fail and the suspend callback wouldn't get called in the first
>> place.
>>
>> Alan Stern
>>
>>
>> 8<---------------------------------------------------------------->8
>>
>> The USB core doesn't properly handle mutual exclusion between
>> resetting a hub and changing the power states of the hub's ports. We
>> need to avoid sending port-power requests to the hub while it is being
>> reset, because such requests cannot succeed.
>>
>> This patch fixes the problem by keeping track of when a reset is in
>> progress. At such times, attempts to suspend (power-off) a port will
>> fail immediately with -EBUSY, and calls to usb_port_runtime_resume()
>> will update the power_is_on flag and return immediately. When the
>> reset is complete, hub_activate() will automatically restore each port
>> to the proper power state.
>>
>> Signed-off-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
>
> Acked-by: Dan Williams <dan.j.williams@xxxxxxxxx>
>
> I'll throw this at the front of my series when resubmitting.
Whoops, this patch is missing its own "Subject:".
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