On Thu, Nov 30, 2017 at 6:50 PM, <[email protected]> wrote:
> Hi,
>
> I'm just getting started on this great platform and I've got some questions
> about capes/overlays on which I thought perhaps someone could share their
> expertise.
>
> Most of the documentation you find online still refers to cape manager and
> slots, which is slightly confusing for beginners. I did find this page [1]
> and I understand (I think) that there is no longer a cape manager and that
> u-boot does the loading of capes.
>
> So first questions:
>
> - Is this assumption correct?
Yes,
> - I do understand the concept of the device tree and loading overlays,
> but... what is the difference between overlays, capes and virtual capes?
> I've seen all mentioned in various places, but nowhere could I find a
> description of each. I've also seen "manual overlays" mentioned. Do they all
> actually refer to the same thing?
Yes,
> - How can one see which capes/overlays are loaded once the system has booted
> up in the new uboot overlays world?
Plug in a USB serial debug cable into the debug header, U-Boot is very
verbose about what loads..
>
> I'm starting to look at the PRUSS and how to use them, and I'm not sure
> which overlays should be loaded to enable them, or if access to them is
> already enabled by default. On /boot/uEnv.txt there seem to be a couple of
> options, one of which is commented out. I notice the difference in the
> naming ('*-RPROC-*', vs. *-UIO-* commented out), so I'm guessing that the
> RPROC PRUSS overlay is loaded and the UIO one is not.
>
> But could someone elaborate a bit more on this?
>
> ###PRUSS OPTIONS
> ###pru_rproc (4.4.x-ti kernel)
> uboot_overlay_pru=/lib/firmware/AM335X-PRU-RPROC-4-4-TI-00A0.dtbo
> ###pru_uio (4.4.x-ti & mainline/bone kernel)
> #uboot_overlay_pru=/lib/firmware/AM335X-PRU-UIO-00A0.dtbo
"uio" has been used since 3.8.x
"pru_rproc" is TI's design, really only used with the "v4.4.x-ti" kernel.
We try to eaisly allow you to swap betwen uio and pru_rproc
> Finally, on my /boot/uEnv.txt file I can see these lines, which I understand
> are for older kernels. As a humble piece of feedback from a newcomer, these
> make the file more confusing for options that no longer apply. Would it not
> make sense to remove them for new images?
>
> ##Example v3.8.x
> #cape_disable=capemgr.disable_partno=
> #cape_enable=capemgr.enable_partno=
>
> ##Example v4.1.x
> #cape_disable=bone_capemgr.disable_partno=
> #cape_enable=bone_capemgr.enable_partno=
Nope, as people still use 3.8.x and 4.1.x+ (pre u-boot overlays)..
Regards,
--
Robert Nelson
https://rcn-ee.com/
--
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