On 7/12/2017 2:06 PM, Baolin Wang wrote:
Hi,
On 12 July 2017 at 15:25, Manu Gautam <mgautam@xxxxxxxxxxxxxx> wrote:
On 7/12/2017 12:19 PM, Baolin Wang wrote:
Hi,
On 3 July 2017 at 19:25, Manu Gautam <mgautam@xxxxxxxxxxxxxx> wrote:
Driver powers-off PHYs and reinitializes DWC3 core and gadget on
resume. While this works fine for gadget mode but in host
mode there is not re-initialization of host stack. Also, resetting
bus as part of bus_suspend/resume is not correct which could affect
(or disconnect) connected devices.
Fix this by not reinitializing core on suspend/resume in host mode
for HOST only and OTG/drd configurations.
But for some mobile devices, they also need suspend/resume in host
mode which will power off dwc3 controller in glue layer. If we remove
dwc3_core_init() for host mode, I am afraid it can not work well in
host mode after resuming dwc3.
Can you point me to a glue driver doing that?
Yes, now there are no glue driver doing that, but for many vendor
trees they will do that. (Our platform will power off dwc3 when
suspending dwc3, but have not upstreamed yet)
Fine, but glue driver still need to take care of re-initialization on
resume with current design.
If dwc3 is powered off on suspend then Xhci level initialization also needed
after
performing dwc3_core_init on resume which is currently not present. So this
seems
to me broken anyway.
Since we've add runtime PM for xhci-plat driver [1], which means we
can runtime suspend/resume xhci device from dwc3 [2].
[1] https://www.spinics.net/lists/linux-usb/msg156077.html
[2] https://patchwork.kernel.org/patch/9471869/
Sure. We can discuss this patch once you re-submit.
One concern I have with the patch is marking ignore_children for dwc3
and as part of
dwc3 suspend/resume invoking
runtime pm on xhci. Ideally pm core should handle it seamlessly i.e.
suspending dwc3
once xhci gets suspended and pm_stay_awake/relax can be used to block
pm_suspend
until runtime suspend of glue driver happens.
But [2] has not applied yet now, I will try to upstream it again. Then
we can suspend xhci device--> suspend dwc3 host---> glue layer can
power off, and it is similar when resuming in host mode.
Do you see any issues with this patch?
I am able to get runtime suspend/resume happening fine with XHCI on my
platform.
It involves runtime suspend/resume of USB HUB and dwc3 glue driver
without any other
change.
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