lkml.org 
[lkml]   [2016]   [May]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [PATCH] dwc3: gadget: Defer starting the gadget device until gadget is power on
Date

Hi

Baolin Wang <baolin.wang@linaro.org> writes:
> Hi Felipe,
>
> On 13 May 2016 at 20:46, Felipe Balbi <balbi@kernel.org> wrote:
>>
>> Hi,
>>
>> Baolin Wang <baolin.wang@linaro.org> writes:
>>>>>> why does it need restart? Why is dwc3 powered off? Who powers it off?
>>>>>
>>>>> Because when the dwc3 Vbus is off (no cable pluging in now),
>>>>> especially for some mobile device, the system need to power off the
>>>>> dwc3 to save power in this situation.
>>>>
>>>> but dwc3 doesn't do this by itself, so who's doing it?
>>>
>>> Yes, the dwc3 clock is controlled by the Soc system, so the Soc system
>>> can disable the dwc3 clock when there is no cable plugging in.
>>
>> understood.
>>
>>>>>> This looks like a *really* bad power management implementation. Do you
>>>>>> have hibernation enabled? Do you have Clock gating enabled? Which dwc3
>>>>>> version are you using? How was it configured?
>>>>>
>>>>> This is not hibernation, we want to power off the dwc3 to save power
>>>>> when no cable plugging in. Yes, we have clock gating, at this
>>>>> situation we will disable the clock and shutdown the phy to save
>>>>> power. For mobile device, most time no cable plugging in, so we need
>>>>> to think about the power consuming. How do you think this requirement?
>>>>
>>>> Well, seems like you're missing *proper* runtime PM. I've been meaning
>>>> to work on it for weeks, but I still have a few other things to do
>>>> before I get to that. In any case, we don't need to do what you did
>>>> here. There are better ways.
>>>
>>> Make sense.
>>
>> cool, if you wanna work on it, let me know and I can give some details
>> of what I have in mind.
>
> Could you explain details to me, and I wanna continue to optimize the
> power management things. Thanks.

I have it half-way done. Have a look at my dwc3-fix-suspend branch on
k.org. I haven't sent because I'm not getting a PME event. Can you test
on your end and let me know what happens?

Note that if cable is disconnected, we will drop RUN/STOP bit. On
runtime_resume, we will restart the controller from scratch (skipping
memory allocations, of course)

--
balbi
[unhandled content-type:application/pgp-signature]
\
 
 \ /
  Last update: 2016-05-17 10:41    [W:0.156 / U:0.248 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site