[lkml]   [2020]   [Dec]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
Subject[PATCH v2 0/2] Allow DWC3 runtime suspend if UDC is unbinded
Changes in v2:
- Modified logic for executing the runtime PM resume. Using a sychronous get
call to avoid race conditions.

During the following scenario, the DWC3 runtime suspend routine is blocked as
the connected flag is still true:

1. Enumerate device w/ host.
2. Gadget is unbinded
- echo "" > /sys/kernel/config/usb_gadget/g1/UDC
3. Disconnect the USB cable (VBUS low)
4. No dwc3_gadget_disconnect_interrupt() seen (since controller is
halted from step#1)
5. Runtime PM autosuspend fails due to "dwc->connected" being true
(cleared in dwc3_gadget_disconnect_interrupt())
6. Gadget binded
- echo udc_name > /sys/kernel/config/usb_gadget/g1/UDC
7. No runtime suspend until cable is plugged in and out

Technically, for device initiated disconnects, there is no active session/link
with the host, so the DWC3 controller should be allowed to go into a low power
state. Also, we need to now consider when re-binding the UDC,
dwc3_gadget_set_speed() is executed before dwc3_gadget_pullup(), so if the DWC3
controller is suspended/disabled, while accessing the DCFG, that could result in
bus timeouts, etc... Change the dwc3_gadget_set_speed() to save the speed
being requested, and program it during dwc3_gadget_run_stop(), which is executed
during PM runtime resume. If not, previous setting will be overridden as we
execute a DWC3 controller reset during PM runtime resume.

Wesley Cheng (2):
usb: dwc3: gadget: Allow runtime suspend if UDC unbinded
usb: dwc3: gadget: Preserve UDC max speed setting

drivers/usb/dwc3/core.h | 1 +
drivers/usb/dwc3/gadget.c | 121 ++++++++++++++++++++++----------------
2 files changed, 71 insertions(+), 51 deletions(-)

The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

 \ /
  Last update: 2020-12-30 00:07    [W:0.027 / U:6.116 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site