On 12/23/2014 11:10 AM, 'dl4mea' via BeagleBoard wrote: > > >> Make sure the ttyO4 driver is loaded via the device-tree (use the >> dtb-rebuilder if needed), and setup the pin multiplexing with the >> installed-by-default "universal" overlay. The intent is to provide >> user-mode control of pin multiplexing so you should be able to enable >> just the Rx/Tx pins or whatever combination of data and handshake pins >> are needed for your application. >> > > Hello Charles, > > I am about in the same situation. As far as I have understood the > "installed-by-default 'universal'" overlay is bound into the Kernel. Am I > right? > In that case, I see that the one bound into Robert's latest builds is > intended for BB-Black, and exports all pins that are not HDMI and not eMMC. > Also right? > However, I want to run the 3.14 on BB-White, and am in special need for > P8.03 P8.04 and P8.05, which are not exported as they are eMMC on the > BB-Black. > What is your recommendation for this situation?
IIRC, on a 'White U-Boot should be loading a different device tree without the HDMI and eMMC sections included. Even on a 'Black you can handle the eMMC pins just like the HDMI (don't have the eMMC hard-code the pinmux values, but use a default pinmux-helper setting instead). This wasn't done for eMMC on the 'Black because of the potential for corrupting data. If a ham-fisted user switches some HDMI pins to the wrong mode, the video display might become unusable, but do the same thing with an eMMC pin and you're almost certainly looking at serious data corruption. Anyway, you'll need to fold the eMMC pinmux pins into the 'bone (white) overlay and you can then use config-pin to setup multiplexing as desired. This hasn't been implemented yet mostly due to a lack of time (and a focus more on moving forward with the 'Black than legacy support for the 'White). Send a pull-request if you get this working and it can be added to the default kernel builds. -- Charles Steinkuehler [email protected] -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" 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.
