Re: [PATCH 2/2] usb: musb: try a race-free wakeup

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Sebastian,

On Mon, Jan 26, 2015 at 2:57 AM, Sebastian Andrzej Siewior
<bigeasy@xxxxxxxxxxxxx> wrote:
> On 01/21/2015 06:06 PM, Bin Liu wrote:
>> Hi Sebastian,
>
> Hi Bin,
>
>> With this patch, hubs stop working on TI AM335x EVMs when autosuspend
>> is enabled.
>>
>> I booted the board, connected a hub to the USB1 host port, it got
>> enumerated properly, then connected a thumb drive to the hub, but the
>> drive was not enumerated, no any log from kernel. Removing the drive,
>> no any kernel message either. Finally removed the hub, no disconnect
>> for the hub. Now check MUSB1 DEVCTL register, it value is 0x5D.
>>
>> Reverted this patch, the issue disappeared. Or disable usbcore
>> autosuspend, the issue did not happen.
>>
>> I tested 7+ hubs, all have the same issue.
>>
>> I tested on git://git.ti.com/ti-linux-kernel/ti-linux-kernel.git, tag
>> ti2014.10.01. have not tested with mainline kernel yet.
>>
>> Have you validated this test case?
>
> No, I had no USB-hub attached. It would be nice if you could figure out
> which part is responsible for the missing detection because otherwise
> suspend/resume is broken.

I think I found the cause. Plugging a device behind a hub, this is
related to runtime PM, so the finish_resume_work() should also be
added in musb_runtime_resume(), also musb_host_resume_root_hub()
should not be moved as did in your patch, this call is used to trigger
the bus resume.

A patch will be coming soon - tomorrow.

Regards,
-Bin.

>
>> Thanks,
>> -Bin.
>
> Sebastian
>
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