Downgrade GSM/UMTS module to USB 2.0 Fullspeed
Hello list, i'am using a GSM/UMTS Module on a PCB which is connected with USB 2.0 Hi-Speed to my imx6ul CPU. To reduce our Electromagnetic compatibility and to make my hardware colleges happy again I want to downgrade to USB Full Speed. How can I tell the Linux Kernel to Do so? I already tried this and looked around in /sys/bus/usb/devices but can't find appropirate place to force it to lower speed. dmesg | grep USB [ 175.775175] usb 1-1: new high-speed USB device number 2 using ci_hdrc [ 175.938753] usb 1-1: New USB device found, idVendor=1e2d, idProduct=005a [ 175.938797] usb 1-1: New USB device strings: Mfr=1, Product=2, SerialNumber=0 [ 176.021420] cdc_acm 1-1:1.0: ttyACM0: USB ACM device [ 176.068150] cdc_acm 1-1:1.2: ttyACM1: USB ACM device [ 176.102410] cdc_acm 1-1:1.4: ttyACM2: USB ACM device [ 176.131074] cdc_acm 1-1:1.6: ttyACM3: USB ACM device [ 176.172841] cdc_acm 1-1:1.11: ttyACM4: USB ACM device [ 176.208768] cdc_acm 1-1:1.13: ttyACM5: USB ACM device /sys/bus/usb/devices# lsusb -t /: Bus 01.Port 1: Dev 1, Class=root_hub, Driver=ci_hdrc/1p, 480M |__ Port 1: Dev 2, If 0, Class=, Driver=cdc_acm, 480M |__ Port 1: Dev 2, If 1, Class=, Driver=cdc_acm, 480M |__ Port 1: Dev 2, If 2, Class=, Driver=cdc_acm, 480M |__ Port 1: Dev 2, If 3, Class=, Driver=cdc_acm, 480M |__ Port 1: Dev 2, If 4, Class=, Driver=cdc_acm, 480M |__ Port 1: Dev 2, If 5, Class=, Driver=cdc_acm, 480M |__ Port 1: Dev 2, If 6, Class=, Driver=cdc_acm, 480M |__ Port 1: Dev 2, If 7, Class=, Driver=cdc_acm, 480M |__ Port 1: Dev 2, If 8, Class=, Driver=, 480M |__ Port 1: Dev 2, If 9, Class=, Driver=, 480M |__ Port 1: Dev 2, If 10, Class=, Driver=, 480M |__ Port 1: Dev 2, If 11, Class=, Driver=cdc_acm, 480M |__ Port 1: Dev 2, If 12, Class=, Driver=cdc_acm, 480M |__ Port 1: Dev 2, If 13, Class=, Driver=cdc_acm, 480M |__ Port 1: Dev 2, If 14, Class=, Driver=cdc_acm, 480M |__ Port 1: Dev 2, If 15, Class=, Driver=, 480M Best Regards, Oliver
On Wed, Jan 18, 2017 at 05:05:34PM +0100, Oliver Graute wrote:
Hello list,
i'am using a GSM/UMTS Module on a PCB which is connected with USB 2.0 Hi-Speed to my imx6ul CPU. To reduce our Electromagnetic compatibility and to make my hardware colleges happy again I want to downgrade to USB Full Speed.
How can I tell the Linux Kernel to Do so?
You can't. It's up to the device to tell the host what "speed" it is running at. See the USB spec for all of the crazy details. I suggest you modify the firmware of your modem to do this, that's the only way it is going to work (note, your device needs to be able to support full speed, it might not be able to do that.) good luck! greg k-h
On 18/01/17, Greg KH wrote:
On Wed, Jan 18, 2017 at 05:05:34PM +0100, Oliver Graute wrote:
Hello list,
i'am using a GSM/UMTS Module on a PCB which is connected with USB 2.0 Hi-Speed to my imx6ul CPU. To reduce our Electromagnetic compatibility and to make my hardware colleges happy again I want to downgrade to USB Full Speed.
How can I tell the Linux Kernel to Do so?
You can't. It's up to the device to tell the host what "speed" it is running at. See the USB spec for all of the crazy details.
ok thx for this important hint
I suggest you modify the firmware of your modem to do this, that's the only way it is going to work (note, your device needs to be able to support full speed, it might not be able to do that.)
I know that the cinterion gsm module support full speed. I have to check their docs how to force the module into fullspeed. Best Regards, Oliver
Hello Oliver, Am 18.01.2017 um 17:05 schrieb Oliver Graute:
Hello list,
i'am using a GSM/UMTS Module on a PCB which is connected with USB 2.0 Hi-Speed to my imx6ul CPU. To reduce our Electromagnetic compatibility and to make my hardware colleges happy again I want to downgrade to USB Full Speed.
i think this topic fits better into the i.MX Community [1] Regards Stefan [1] - https://community.nxp.com/community/imx
participants (3)
-
Greg KH -
Oliver Graute -
Stefan Wahren