This makes a whole lot more sense now, because I swear I had it working on
those GPIO ports at one point. I think I had exported pins manually while
testing things. Thanks for the help!

On Wed, Apr 29, 2020 at 2:59 PM John Allwine <[email protected]> wrote:

> That did it! I exported pin 8.43:
>
> echo 226 > /sys/class/gpio/export
>
> And now the PRUs can write to the set and clear addresses for GPIO8.
>
> I also exported 8.26:
>
> echo 124 > /sys/class/gpio/export
>
> And now the PRUs can write to the set and clear addresses for GPIO4.
>
> On Wed, Apr 29, 2020 at 11:42 AM Jason Kridner <[email protected]>
> wrote:
>
>>
>>
>> On Wed, Apr 29, 2020 at 12:38 PM Charles Steinkuehler <
>> [email protected]> wrote:
>>
>>> Regarding your bus errors, I don't see anything in the TRM that
>>> indicates the PRU shouldn't be able to talk to all of the GPIO banks.
>>>
>>> I have, however, seen bus errors on uninitialized GPIO banks which come
>>> up disabled by default.  Check to make sure at least one GPIO pin is
>>> exported by the Linux Kernel (either manually or via device tree) and
>>> see if the bus errors go away.
>>>
>>
>> I'll double-down on that feedback. I forwarded this to the team at TI and
>> they said it is likely that the GPIO bank doesn't have its clock enabled. I
>> inquired what the minimal action to enable the clock would be, but haven't
>> heard back yet. Enabling one of the GPIOs in the bank in Linux seems like a
>> sure way to do it.
>>
>> I'll get back when I can find anything more minimal than that.
>>
>>
>>>
>>>
>>> On 4/28/2020 4:45 PM, John Allwine wrote:
>>> > Using that test, I was able to quickly check to see which GPIO ports I
>>> was
>>> > able to write to from the PRU. GPIO 1, 4 and 8 errored. GPIO 2 doesn't
>>> have
>>> > any pins mapped to P8 or P9 headers, so that leaves GPIO 3, 5, 6 and 7
>>> that
>>> > I can use for hal_pru_generic. The P8 and P9 pins that are mapped to
>>> GPIO 4
>>> > and 8 can all be mapped to direct outputs on certain PRUs. I'll need to
>>> > document how each pin can be used, but it seems like just about all
>>> the P8
>>> > and P9 pins can be used as long as you know which PRU to run it on for
>>> > direct outputs and which are suitable to be used as GPIO outputs.
>>> >
>>> > On Tue, Apr 28, 2020 at 1:59 PM John Allwine <[email protected]>
>>> > wrote:
>>> >
>>> >> Ok, I have a more localized test that triggers the exception:
>>> >>
>>> >>
>>> https://github.com/PocketNC/cloud9-examples/blob/test-pru-gpio-access/BeagleBone/AI/pru/doNothingToGPIO8.pru1_1.c
>>> >>
>>> >> Two stack traces can be seen in dmesg after running that on the PRU.
>>> If it
>>> >> has something to do with the device tree, this is the overlay I'm
>>> using:
>>> >>
>>> >>
>>> https://github.com/PocketNC/BeagleBoard-DeviceTrees/blob/pocketnc-ai-test/src/arm/am5729-beagleboneai-pocketnc-pro.dts
>>> >>
>>> >> On Tue, Apr 28, 2020 at 1:20 PM John Allwine <[email protected]>
>>> wrote:
>>> >>
>>> >>> Are there any ramifications of the PRU writing 0 to both the set and
>>> >>> clear addresses of GPIO8 (0x48053190 and 0x48053194), when the
>>> device tree
>>> >>> has several overlapping pins allocated to being direct outputs on
>>> the PRU?
>>> >>> The issue seems to arise when I write to those two addresses on the
>>> PRU, as
>>> >>> well as the set and clear addresses of GPIO4 (0x48059190 and
>>> 0x48059194).
>>> >>> What could cause that to trigger an exception in the kernel?
>>> >>>
>>> >>> On Tue, Apr 28, 2020 at 12:19 PM John Allwine <[email protected]>
>>> wrote:
>>> >>>
>>> >>>> It seems that even if I hardcode the addresses in there (to
>>> eliminate
>>> >>>> the possibility that my registers were getting overwritten
>>> somewhere), that
>>> >>>> I get the bus error.  Does enabling the OCP Master port work the
>>> same way
>>> >>>> as on the BBB? It's supposedly being set here:
>>> >>>>
>>> https://github.com/PocketNC/machinekit-hal/blob/c8b38386d87abc45baa33593681cbae46d996980/src/hal/drivers/hal_pru_generic/pru_generic.p#L174-L176
>>> >>>>
>>> >>>> On Tue, Apr 28, 2020 at 11:47 AM John Allwine <[email protected]>
>>> wrote:
>>> >>>>
>>> >>>>> It's the hal_pru_generic code. It definitely smells like a bus
>>> error.
>>> >>>>> In fact, if I comment out the lines that write to the GPIO, it
>>> stops
>>> >>>>> happening, so it seems like I have the wrong addresses in there,
>>> but I'm
>>> >>>>> struggling figuring out how that could be.
>>> >>>>>
>>> >>>>> These lines are where the GPIO ports are written to in memory:
>>> >>>>>
>>> >>>>>
>>> https://github.com/PocketNC/machinekit-hal/blob/c8b38386d87abc45baa33593681cbae46d996980/src/hal/drivers/hal_pru_generic/pru_wait.p#L214-L217
>>> >>>>>
>>> >>>>> Theoretically, the addresses should be set to the clear addresses
>>> of
>>> >>>>> GPIO3, GPIO5, GPIO6 and GPIO7:
>>> >>>>>
>>> >>>>> Addresses defined here:
>>> >>>>>
>>> >>>>>
>>> https://github.com/PocketNC/machinekit-hal/blob/c8b38386d87abc45baa33593681cbae46d996980/src/hal/support/pru/pru.h#L303-L307
>>> >>>>>
>>> >>>>> Loaded into registers here:
>>> >>>>>
>>> >>>>>
>>> https://github.com/PocketNC/machinekit-hal/blob/c8b38386d87abc45baa33593681cbae46d996980/src/hal/drivers/hal_pru_generic/pru_generic.p#L261-L264
>>> >>>>>
>>> >>>>>
>>> >>>>>
>>> >>>>>
>>> >>>>>
>>> >>>>>
>>> >>>>>
>>> >>>>> On Tue, Apr 28, 2020 at 10:50 AM Jason Kridner <
>>> >>>>> [email protected]> wrote:
>>> >>>>>
>>> >>>>>> What is the code running on PRUSS2 PRU1?
>>> >>>>>>
>>> >>>>>> This line kinda spells out an illegal access by that PRU or of
>>> that
>>> >>>>>> PRU:
>>> >>>>>> MASTER PRUSS2 PRU1 TARGET L4_PER1_P3 (Idle): Data Access in
>>> Supervisor
>>> >>>>>> mode during Functional access
>>> >>>>>>
>>> >>>>>> Looks like the error is from here:
>>> >>>>>>
>>> https://github.com/beagleboard/linux/blob/7a920684860a790099061b67961d0b5ffa033fdf/drivers/bus/omap_l3_noc.c#L135
>>> >>>>>>
>>> >>>>>> Looks like a bus exception to me.
>>> >>>>>>
>>> >>>>>> On Tue, Apr 28, 2020 at 11:46 AM <[email protected]> wrote:
>>> >>>>>>
>>> >>>>>>> I'm getting this stack trace in dmesg, but I'm unsure what it
>>> means
>>> >>>>>>> or how to figure out what it means. As far as I can tell, the
>>> code running
>>> >>>>>>> on the PRU is working. I'm generating a 100Khz signal on a
>>> direct output,
>>> >>>>>>> and am able to successfully measure this signal. The Beaglebone
>>> is locking
>>> >>>>>>> up, though, and I believe this stack trace is being spammed so
>>> heavily that
>>> >>>>>>> the logging is taking over the CPU and my ssh shell gets locked
>>> out.
>>> >>>>>>>
>>> >>>>>>> I'm using this device tree overlay:
>>> >>>>>>>
>>> https://github.com/PocketNC/BeagleBoard-DeviceTrees/blob/pocketnc-ai-test/src/arm/am5729-beagleboneai-pocketnc-pro.dts
>>> >>>>>>>
>>> >>>>>>> The code I'm running is implemented in PRU Assembly that is
>>> assembled
>>> >>>>>>> with pasm. pasm outputs a .bin file and I need a .elf file for
>>> running it
>>> >>>>>>> with remoteproc, so I'm jumping through some hoops to do that
>>> conversion.
>>> >>>>>>> The elf file does seem to work, but I'm not sure if I need to do
>>> more to
>>> >>>>>>> ensure I'm specifying what resources I need access to or
>>> something like
>>> >>>>>>> that. I can go into more detail if need be.
>>> >>>>>>>
>>> >>>>>>> The stack trace is below. Any ideas about what is going on are
>>> >>>>>>> appreciated!
>>> >>>>>>>
>>> >>>>>>> [  168.153783] ------------[ cut here ]------------
>>> >>>>>>> [  168.153829] WARNING: CPU: 0 PID: 0 at
>>> >>>>>>> drivers/bus/omap_l3_noc.c:147 l3_interrupt_handler+0x27c/0x39c
>>> >>>>>>> [  168.153851] 44000000.ocp:L3 Custom Error: MASTER PRUSS2 PRU1
>>> >>>>>>> TARGET L4_PER1_P3 (Idle): Data Access in Supervisor mode during
>>> Functional
>>> >>>>>>> access
>>> >>>>>>> [  168.153865] Modules linked in: xt_conntrack ipt_MASQUERADE
>>> >>>>>>> nf_nat_masquerade_ipv4 rpmsg_rpc rpmsg_proto bnep btsdio
>>> bluetooth
>>> >>>>>>> ecdh_generic brcmfmac pvrsrvkm(O) brcmutil cfg80211
>>> uio_pruss_shmem evdev
>>> >>>>>>> joydev stmpe_adc omap_remoteproc virtio_rpmsg_bus rpmsg_core
>>> 8021q garp mrp
>>> >>>>>>> stp llc iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4
>>> nf_nat
>>> >>>>>>> usb_f_acm nf_conntrack u_serial usb_f_ecm usb_f_mass_storage
>>> iptable_mangle
>>> >>>>>>> iptable_filter usb_f_rndis u_ether libcomposite cmemk(O)
>>> uio_pdrv_genirq
>>> >>>>>>> uio spidev pruss_soc_bus pru_rproc pruss pruss_intc ip_tables
>>> x_tables
>>> >>>>>>> [  168.154474] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G
>>> W  O
>>> >>>>>>>    4.14.108-ti-r119 #1
>>> >>>>>>> [  168.154490] Hardware name: Generic DRA74X (Flattened Device
>>> Tree)
>>> >>>>>>> [  168.154538] [<c0113180>] (unwind_backtrace) from [<c010d690>]
>>> >>>>>>> (show_stack+0x20/0x24)
>>> >>>>>>> [  168.154575] [<c010d690>] (show_stack) from [<c0ce54f4>]
>>> >>>>>>> (dump_stack+0x80/0x94)
>>> >>>>>>> [  168.154609] [<c0ce54f4>] (dump_stack) from [<c013f5b8>]
>>> >>>>>>> (__warn+0xf8/0x110)
>>> >>>>>>> [  168.154636] [<c013f5b8>] (__warn) from [<c013f628>]
>>> >>>>>>> (warn_slowpath_fmt+0x58/0x74)
>>> >>>>>>> [  168.154667] [<c013f628>] (warn_slowpath_fmt) from [<c0741e10>]
>>> >>>>>>> (l3_interrupt_handler+0x27c/0x39c)
>>> >>>>>>> [  168.154703] [<c0741e10>] (l3_interrupt_handler) from
>>> [<c01abcbc>]
>>> >>>>>>> (__handle_irq_event_percpu+0xbc/0x280)
>>> >>>>>>> [  168.154734] [<c01abcbc>] (__handle_irq_event_percpu) from
>>> >>>>>>> [<c01abebc>] (handle_irq_event_percpu+0x3c/0x8c)
>>> >>>>>>> [  168.154761] [<c01abebc>] (handle_irq_event_percpu) from
>>> >>>>>>> [<c01abf54>] (handle_irq_event+0x48/0x6c)
>>> >>>>>>> [  168.154792] [<c01abf54>] (handle_irq_event) from [<c01aff78>]
>>> >>>>>>> (handle_fasteoi_irq+0xc8/0x17c)
>>> >>>>>>> [  168.154822] [<c01aff78>] (handle_fasteoi_irq) from
>>> [<c01aad7c>]
>>> >>>>>>> (generic_handle_irq+0x34/0x44)
>>> >>>>>>> [  168.154850] [<c01aad7c>] (generic_handle_irq) from
>>> [<c01ab390>]
>>> >>>>>>> (__handle_domain_irq+0x8c/0xfc)
>>> >>>>>>> [  168.154879] [<c01ab390>] (__handle_domain_irq) from
>>> [<c01015e0>]
>>> >>>>>>> (gic_handle_irq+0x4c/0x88)
>>> >>>>>>> [  168.154908] [<c01015e0>] (gic_handle_irq) from [<c0d02bcc>]
>>> >>>>>>> (__irq_svc+0x6c/0xa8)
>>> >>>>>>> [  168.154925] Exception stack(0xc1501ed8 to 0xc1501f20)
>>> >>>>>>> [  168.154946] 1ec0:
>>> >>>>>>>       00000001 00000000
>>> >>>>>>> [  168.154973] 1ee0: fe600000 00000000 c1500000 c1504e60 c1504dfc
>>> >>>>>>> c14cbb78 c1501f48 00000000
>>> >>>>>>> [  168.154997] 1f00: 00000000 c1501f34 c1501f14 c1501f28 c012fcb8
>>> >>>>>>> c0109768 600f0013 ffffffff
>>> >>>>>>> [  168.155031] [<c0d02bcc>] (__irq_svc) from [<c0109768>]
>>> >>>>>>> (arch_cpu_idle+0x30/0x4c)
>>> >>>>>>> [  168.155061] [<c0109768>] (arch_cpu_idle) from [<c0d02044>]
>>> >>>>>>> (default_idle_call+0x30/0x3c)
>>> >>>>>>> [  168.155092] [<c0d02044>] (default_idle_call) from [<c018cc6c>]
>>> >>>>>>> (do_idle+0x180/0x214)
>>> >>>>>>> [  168.155124] [<c018cc6c>] (do_idle) from [<c018d00c>]
>>> >>>>>>> (cpu_startup_entry+0x28/0x2c)
>>> >>>>>>> [  168.155156] [<c018d00c>] (cpu_startup_entry) from [<c0cfb4b0>]
>>> >>>>>>> (rest_init+0xdc/0xe0)
>>> >>>>>>> [  168.155194] [<c0cfb4b0>] (rest_init) from [<c1400eb8>]
>>> >>>>>>> (start_kernel+0x434/0x45c)
>>> >>>>>>> [  168.155217] ---[ end trace d9047b952a20ba7f ]---
>>> >>>>>>>
>>> >>>>>>>
>>> >>>>>>>
>>> >>>>>>> --
>>> >>>>>>> For more options, visit http://beagleboard.org/discuss
>>> >>>>>>> ---
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>>> >>>>>>> <
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>>> >
>>> >>>>>>> .
>>> >>>>>>>
>>> >>>>>>
>>> >>>>>>
>>> >>>>>> --
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>>> around
>>> >>>>>> open hardware computing
>>> >>>>>>
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>>> >
>>> >>> .
>>> >>>
>>> >> --
>>> >> For more options, visit http://beagleboard.org/discuss
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>>> >
>>> >> .
>>> >>
>>> >
>>>
>>> --
>>> Charles Steinkuehler
>>> [email protected]
>>>
>>> --
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>>
>>
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