I've confirmed that all desired functionality with PRU and IOs is restored, with full access to all the exposed PRU0 (output) pins. Thanks for the help.
I revisited the elinux.org BB pages, and understand what is being described there (for the most part) -- but not why. Is there a group/list/forum where the discussion and decisions leading to u-boot overlays (replacing the "old way") is available? Here's what I'm trying to understand: What is benefit of u-boot overlays over the "old way"? Is it that custom capes can be specified for loading by u-boot, rather than the script workaround that is referred to in the elinux:BB page? For "non-custom" overlays, how is it different (other than syntax) to enable u-boot overlays and then provide directives to enable/disable as u-boot overlays -- compared to using the previous capemgr.enable_partno=XXX method? With u-boot overlays, is it still possible to specify the dtb (not overlay) that is loaded, rather than what is auto-detected? The biggest confusion I have is with the overarching strategy: my understanding is that DeviceTree exists specifically to avoid a multitude of board files and other junk compiled into the kernel for each platform derivative. It's been a challenge but I can appreciate the vision and value once there. This was done by creating a way to specify the specific hardware configuration in a data model (and provide parameters to more generic drivers in the kernel to make it all work). IIUC, doesn't building capes (by way of overlays) into u-boot go against that concept? Building a new u-boot to add an overlay is easier than adding to the kernel (and not polluting mainline). But why not have u-boot look in a designated location for a specified overlay which it knows nothing about, only to load it? [realizing that I may have just "just..." discounted a huge technical problem in the way this question is formed - not intentionally, but from lack of more detailed understanding of how the pieces all fit together] On Friday, March 23, 2018 at 6:12:11 PM UTC-7, RobertCNelson wrote: > > On Fri, Mar 23, 2018 at 7:59 PM, ags <[email protected] <javascript:>> > wrote: > > That *seems* to have fixed it. Will need to run a test to be sure. It > does > > allow me to configure the audio pin as pruout, and I do see gpio entries > and > > the uio events in sysfs. > > > > I was wondering if it was the old U-Boot - I presume the old one doesn't > > understand uboot overlays?? > > That is correct.. > > > > > (was I correct to remove "cape_universal=enable" from the kernel command > > line entry in uEnv.txt (or does it not matter once uboot overlays are > > enabled?) > > it'll actually get ignored... > > > > > The syntax of the directives I added to uEnv.txt look (to me) like they > are > > hard-coded into u-boot -- is that correct? That is, rather than generic > > directives that look like: > > > > enable_uboot_overlay=<some overlay found in /lib/firmware> > > enable_uboot_overlay=<some other overlay found in /lib/firmware> > > disable_uboot_overlay=<yet another...> > > > > we now have: > > > > enable_uboot_overlays=1 # OK, that seems generic... tell > > u-boot to handle overlays > > > > disable_uboot_overlay_audio=1 . # "audio" is hardcoded in the > directive > > itself > > onboard devices: > > > https://elinux.org/Beagleboard:BeagleBoneBlack_Debian#U-Boot_Disable_on-board_devices > > > (these change cape-universal)... > > > uboot_overlay_pru=/lib/firmware/AM335X-PRU-UIO-00A0.dtbo # > u-boot > > even knows about prus? > > pru is special: > > https://elinux.org/Beagleboard:BeagleBoneBlack_Debian#U-Boot_PRU_Options > > > enable_uboot_cape_universal=1 > > # ... and cape_universal? > > Correct, although i'm working on a project to have that auto-enabled.. > > Regards, > > -- > Robert Nelson > https://rcn-ee.com/ > -- 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]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/77780e48-089a-4bb6-b883-ee95a589fe8d%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
