This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

AM37x EHCI-HCD problems

Hi,

We are using VAR-SOM-OM37 module and want to use up to eight external displays with a mcp2210 chip from Mikrochip on USB host via an USB hub. My problem is, that if more than one device is plugged, (i guess) the driver seems to be too slow to handle the write process to the displays. If i plug in the hub on the OTG port, then musb_hdrc is loaded and all displays work fine, but it could be faster.

We can't upgrade from kernel 2.6.32 by now, but is there any way to speed up the USB host side?

Kind regards,

Silke

  • Hi Silke,

    I will bring this to the attention of the factory team.

  • Hi Biser,

    thanks for your answer!

    Some further information: Using OTG, musb_hdrc driver is loaded, using host, ehci-omap is loaded

    usb 2-1.3.7.2: new full speed USB device using ehci-omap and address 6
    usb 2-1.3.7.2: New USB device found, idVendor=04d8, idProduct=00de
    usb 2-1.3.7.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
    usb 2-1.3.7.2: Product: MCP2210 USB to SPI Master
    usb 2-1.3.7.2: Manufacturer: Microchip Technology Inc.
    usb 2-1.3.7.2: SerialNumber: 0000134680

    MCP2210 is a full speed device. I've read, that ehci can only work with high speed devices - could this be the problem? If one device is plugged ("behind" an external 2.0 Hub) on the host, then everything works fine but if two or more are plugged, then it seems that there are some timing conflicts. 

    With OTG, all 8 devices run quite good, but it could be a bit faster.

    BR, Silke