On Mon, 7 Jan 2019, Kai Heng Feng wrote: > Hi, > > > On Dec 3, 2018, at 18:26, Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx> wrote: > > > > USB Bluetooth controller QCA ROME (0cf3:e007) sometimes stops working > > after S3: > > [ 165.110742] Bluetooth: hci0: using NVM file: qca/nvm_usb_00000302.bin > > [ 168.432065] Bluetooth: hci0: Failed to send body at 4 of 1953 (-110) > > > > After some experiments, I found that disabling LPM can workaround the > > issue. > > > > On some platforms, the USB power is cut during S3, so the driver uses > > reset-resume to resume the device. During port resume, LPM gets enabled > > twice, by usb_reset_and_verify_device() and usb_port_resume(). > > > > So let's enable LPM for just once, as this solves the issue for the > > device in question. > > > > Also consolidate USB2 LPM functions to usb_enable_usb2_hardware_lpm() > > and usb_disable_usb2_hardware_lpm(). > > Please review my new approach, hopefully this can be included in Linux v5.0. > > > > > Signed-off-by: Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx> > > --- > > v4: > > - Use usb_enable_usb2_hardware_lpm() and > > usb_disable_usb2_hardware_lpm() to control USB2 LPM. > > v3: > > - Consolidate udev->usb2_hw_lpm_capable and udev->usb2_hw_lpm_enabled > > check to usb_set_usb2_hardware_lpm(). > > v2: > > - Check udev->usb2_hw_lpm_enabled before calling usb_port_resume(). > > > > drivers/usb/core/driver.c | 23 +++++++++++++++++++---- > > drivers/usb/core/hub.c | 16 ++++++---------- > > drivers/usb/core/message.c | 3 +-- > > drivers/usb/core/sysfs.c | 5 ++++- > > drivers/usb/core/usb.h | 10 ++++++++-- > > 5 files changed, 38 insertions(+), 19 deletions(-) Reviewed-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
