Le samedi 28 mars 2015 à 17:07 +0100, Paul Kocialkowski a écrit : > I've been trying to use the Cubieboard2 USB OTG/DRC port (the mini USB > one) in U-Boot and it seems that VBUS is always enabled on it (by > measuring the voltage on the pin of the mini USB connector that is close > to the ethernet connector, it always reads 5V). > > The schematics mention a TCS9708 USB switch for OTG that I cannot seem > to find on the actual board (I see only 2 TCS9708, one for each USB host > port). Hence, I'm worried that the schematics don't actually match the > board and that the OTG VBUS is always at 5V. > > The TCS9708 should be controlled by the PB9 GPIO, but toggling it > doesn't change anything. The VBUS detection GPIO (PH5) always shows 1.
Apparently, the TCS9708 is not populated and the resistor marked R93 on the schematics and R27 on the layout is populated instead (with NC value). > Is this behaviour reproducible on every such board? If so, should we > somewhat bypass the VBUS detection code in U-Boot so that the OTG port > becomes usable in host mode too? In that configuration, it's probably not very wise to use the board in OTG device mode. I think something ought to be done to reflect this in U-Boot and in the upcoming OTG/DRC Linux kernel support. The kernel is more problematic since the board switches between host and device "on the fly" (while in U-Boot, MUSB has to be selected at build-time so there is no immediate problem for users that use the provided config as-is). -- Paul Kocialkowski, Replicant developer Replicant is a fully free Android distribution running on several devices, a free software mobile operating system putting the emphasis on freedom and privacy/security. Website: http://www.replicant.us/ Blog: http://blog.replicant.us/ Wiki/tracker/forums: http://redmine.replicant.us/ -- You received this message because you are subscribed to the Google Groups "linux-sunxi" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
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