> -----Original Message----- > From: Fabio Estevam <festevam@xxxxxxxxx> > Sent: Tuesday, December 13, 2022 2:11 AM > To: bjorn@xxxxxxx; Peter Chen <peter.chen@xxxxxxxxxx>; Marek Vasut > <marex@xxxxxxx>; Jun Li <jun.li@xxxxxxx> > Cc: netdev <netdev@xxxxxxxxxxxxxxx>; USB list <linux-usb@xxxxxxxxxxxxxxx>; > Alexander Stein <alexander.stein@xxxxxxxxxxxxxxx>; Schrempf Frieder > <frieder.schrempf@xxxxxxxxxx> > Subject: imx7: USB modem reset causes modem to not re-connect > > Hi, > > On an imx7d-based board running kernel 5.10.158, I noticed that a > Quectel BG96 modem is gone after sending a reset command via AT: > > # microcom /dev/ttyUSB3 > >AT+CFUN=1,1 > OK > usb 2-1: USB disconnect, device number 6 > option1 ttyUSB0: GSM modem (1-port) converter now disconnected from ttyUSB0 > option 2-1:1.0: device disconnected > option1 ttyUSB1: GSM modem (1-port) converter now disconnected from ttyUSB1 > option 2-1:1.1: device disconnected > option1 ttyUSB2: GSM modem (1-port) converter now disconnected from ttyUSB2 > option 2-1:1.2: device disconnected > option1 ttyUSB3: GSM modem (1-port) converter now disconnected from ttyUSB3 > option 2-1:1.3: device disconnected > qmi_wwan 2-1:1.4 wwan0: unregister 'qmi_wwan' usb-ci_hdrc.1-1, WWAN/QMI > device > > # lsusb > Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub > Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub > > The USB modem is gone. > > Forcing an 'echo on' to power/control makes the USB modem reappear: > > # echo 'on' > /sys/bus/usb/devices/usb2/power/control > usb 2-1: new high-speed USB device number 7 using ci_hdrc > usb 2-1: New USB device found, idVendor=2c7c, idProduct=0296, bcdDevice= > 0.00 > usb 2-1: New USB device strings: Mfr=3, Product=2, SerialNumber=4 > usb 2-1: Product: Qualcomm CDMA Technologies MSM > usb 2-1: Manufacturer: Qualcomm, Incorporated > usb 2-1: SerialNumber: 7d1563c1 > option 2-1:1.0: GSM modem (1-port) converter detected > usb 2-1: GSM modem (1-port) converter now attached to ttyUSB0 > option 2-1:1.1: GSM modem (1-port) converter detected > usb 2-1: GSM modem (1-port) converter now attached to ttyUSB1 > option 2-1:1.2: GSM modem (1-port) converter detected > usb 2-1: GSM modem (1-port) converter now attached to ttyUSB2 > option 2-1:1.3: GSM modem (1-port) converter detected > usb 2-1: GSM modem (1-port) converter now attached to ttyUSB3 > qmi_wwan 2-1:1.4: cdc-wdm0: USB WDM device > qmi_wwan 2-1:1.4 wwan0: register 'qmi_wwan' at usb-ci_hdrc.1-1, > WWAN/QMI device, 12:bc:8c:zz:yy:xx > > # lsusb > Bus 002 Device 007: ID 2c7c:0296 Quectel Wireless Solutions Co., Ltd. > BG96 CAT-M1/NB-IoT modem > Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub > Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub > > Sending the AT reset command afterward works fine, and the modem keeps > connected. On this try, is the modem "firstly disconnect and then connect" or it "keeps connects before and after" you sending the AT reset command? >From your next email, I am seeing it's a "firstly disconnect and then connect" in that try, I want to understand what's the modem behavior of AT reset command, both on SW(host driver, force a disconnect?) and HW(modem side, it actually physically disconnect and then connect?). Li Jun > > Previously, this board used a vendor-based 4.14 kernel and such a > problem did not happen. > > Kernels 5.10 and 4.14 have the same 'auto' option selected by default. > > Also tested kernel 6.1 and it behaves the same as 5.10.158. > > What can be done so that the reset modem command does not cause the > modem to disappear by default? > > Thanks, > > Fabio Estevam
