On 08/18/2015 05:55 AM, Guillaume Gardet wrote:

Hi Stephen,

I want to add USB keyboard support to raspberry pi but I get the following error when I do 'usb start' with a keyboard plugged-in: unable to get device descriptor (error=-22)

Ethernet chip and mass storage devices are found.

I found this thread from February: http://lists.denx.de/pipermail/u-boot/2015-February/206593.html which says:

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This error is because the keyboard driver uses interrupt transfers, and
these aren't implemented in DWC2

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But in April, you added a patch series including "usb: dwc2: implement interrupt transfers". But there is also a note:

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With all these commits applied, both my USB keyboards (one LS Lenovo

and one FS Dell) work correctly when there is no USB hub between the SoC and the keyboard; We still need split transactions to be implemented for hubs to work.

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So, I guess this is expected that USB keyboard does not work on DWC2 / RPi B since it uses a USB hub (SMSC LAN9512)?

Yes, that's unfortunately expected at present.