i.MX ProcessorsのトピックRe: USB power setting

USB power setting

srcoolz — Wed, 25 Oct 2017 01:20:44 GMT

Hello,

I am using the iMX6UL part and wanted to know how to set the USB current level. By default, USB Host provides 100mA @ 5V to begin and then after negotiations can provide upto 500mA. Is there a way in software (USB driver) to ensure that during negotiations the USB Host (iMX6UL) only allows upto 100mA and no more.

I understand that this is not USB 2.0 compliant - but in my system I'm unable to provide more than 0.5W of power to USB devices. We plan to use only USB memory stick as acceptable devices.

Can you please help me with the setup or modifications needed to the USB driver?

Thank you

Regards

Santhosh

Re: USB power setting

igorpadykov — Wed, 25 Oct 2017 03:02:44 GMT

Hi Santhosh

usb driver is described in Chapter 39 CHIPIDEA USB Driver
attached Linux Manual and from sources seems driver supports only default 100mA setting.

Best regards
igor
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Re: USB power setting

srcoolz — Wed, 25 Oct 2017 14:37:54 GMT

Hello Igor,

Thank you for your quick response. I reviewed the Manual and was unable to find the current setting. Can you please point me to the correct source file that I could review?

Additionally, I'm hoping that there is a setting in the driver which will allow the USB Host to deny the request from devices when they request additional current. (i.e. only allow max 100mA (default)).

Can you please confirm that if I'm using USB1 in HOST mode only then connecting the VBUS enable to the USB_OTG1_PWR will allows the USB PHY to control the power (On/Off) to the device?

Thank you

Regards

Santhosh