[0/4] usb: gadget: serial: add supend resume support

Message

Fabrice Gasnier April 21, 2020, 12:32 p.m. UTC

This series handles an issue seen when doing basic testing using ACM or SERIAL
gadget functions like in [1], and using the DWC2 gadget driver. It occurs when
the HOST has suspended the bus before testing, in this order:
- On the device:
  cat /dev/ttyGS<Y>
  Dmesg error log is seen on device side:
  configfs-gadget gadget: acm ttyGS0 can't notify serial state, -11
- On the host:
  echo test > /dev/ttyACM<X>
  The bus resumes, but the serial link isn't functional.

So, implement suspend/resume callbacks in gadget serial drivers to handle this.
There is a precursor patch in DWC2 to enable submitting usb requests from the
gadget resume routine, once in L0 state.

[1] https://www.kernel.org/doc/html/latest/usb/gadget-testing.html#testing-the-acm-function

Fabrice Gasnier (4):
  usb: dwc2: gadget: move gadget resume after the core is in L0 state
  usb: gadget: u_serial: add suspend resume callbacks
  usb: gadget: f_serial: add suspend resume callbacks
  usb: gadget: f_acm: add suspend resume callbacks

 drivers/usb/dwc2/core_intr.c           | 10 ++++--
 drivers/usb/gadget/function/f_acm.c    | 16 ++++++++++
 drivers/usb/gadget/function/f_serial.c | 16 ++++++++++
 drivers/usb/gadget/function/u_serial.c | 57 +++++++++++++++++++++++++++++-----
 drivers/usb/gadget/function/u_serial.h |  2 ++
 5 files changed, 90 insertions(+), 11 deletions(-)