>From what I've found, the "no children" error refers to a pruss entry in
the device tree that looks like this:
fragment@1 {
target = <&pruss>;
__overlay__ {
status = "okay";
pinctrl-names = "default";
pinctrl-0 = <&your_pru_pins>;
};
};
This used to work just fine, but now it needs to have one or more entries
below pinctrl-0 describing your pins, like this:
fragment@1 {
target = <&pruss>;
__overlay__ {
status = "okay";
pinctrl-names = "default";
pinctrl-0 = <&your_pru_pins>;
my_pins{
pin-names = "name1", "name2" ... ;
gpios = <&gpioX PN 0
&gpioY PN 0
... >;
};
# possibly more like above
};
};
depending on which gpio groups and PNs(pin numbers) you'd like the pruss to
be associated with.
I am not sure how you specify that you don't want ANY pins though, unless
you would then just not have the pinctrl entries above and only the status
= "okay" line. That is probably it, since this is how the
"enable-uio-pruss" device tree file I have seems to work and gets no "no
children" errors. At any rate, this does
work on 4.9, and would likely work on 4.4 or maybe even 4.1. I believe the
code that produces this "no children" error is looking for entries like
this in the device tree if you say you want some kind of pinctrl. I did
see the patch that needs to be commented out if you want your old device
tree files to work, but I can't remember where it is. I'm sure someone can
point right to it.
On Tuesday, April 5, 2016 at 9:22:20 AM UTC-4, frank brewer wrote:
>
> I saw others also had this problem at 4.1.x kernel as well, but seems like
> it is fixed with a patch. However I still get this problem, could you
> please help me?
>
>
> debian@arm:~/test$ sudo ./testLED
> prussdrv_open() failed
>
>
>
> debian@arm:~/test$ dmesg | grep -i pru
> [ 209.806504] bone_capemgr bone_capemgr: part_number 'EBB-PRU-Example',
> version 'N/A'
> [ 209.806653] bone_capemgr bone_capemgr: slot #4: 'Override Board
> Name,00A0,Override Manuf,EBB-PRU-Example'
> [ 209.812435] bone_capemgr bone_capemgr: slot #4: dtbo
> 'EBB-PRU-Example-00A0.dtbo' loaded; overlay id #0
> [ 209.857210] pruss_uio 4a300000.pruss: No children
>
> debian@arm:~/test$ lsb_release -irc
> Distributor ID: Debian
> Release: 8.4
> Codename: jessie
>
> debian@arm:~/test$ uname -or
> 4.1.20-bone-rt-r20 GNU/Linux
>
> debian@arm:~/chp13/ledButton$ cat $SLOTS
> 0: PF---- -1
> 1: PF---- -1
> 2: PF---- -1
> 3: PF---- -1
> 4: P-O-L- 0 Override Board Name,00A0,Override Manuf,EBB-PRU-Example
>
> debian@arm:~/chp13/ledButton$ lsmod
> Module Size Used by
> uio_pruss 4582 0
>
>
>
>
>
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