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DM816x USB ports

Bitlord
Intellectual 565 points

Hi guys,

I believe there is a bug in the kernel source for the musb PHY. Two files: arch/arm/plat-omap/include/plat/usb.h and arch/arm/mach-omap2/usb-musb.c.

usb.h, line 337 defines TI816X_PHY_TXRISETUNE as 1. It get applied in usb-musb.c, line ~139 but never shifted correctly compared to the reference manual (sec 24.9.8.3) This also applies for TI816X_PHY_TXVREFTUNE and TI816X_PHY_TXPREEMTUNE.

Also, we are experiencing some electrical inconsistencies on the USB ports and would like to adjust some of the parameters. Is it possible to get more information on the actual bit values? For instance, TXFSLSTUNE is 4 bit wide and it adjusts the impedance but by how much and would a larger number result in more impedance?

Best,

Andreas