Re: [PATCH v2 01/14] dt-bindings: remoteproc: Add TI PRUSS bindings

From: Suman Anna
Date: Wed Feb 13 2019 - 22:02:51 EST

On 2/5/19 10:41 AM, Tony Lindgren wrote:
> * Roger Quadros <rogerq@xxxxxx> [190205 09:40]:
>> On 04/02/19 18:33, Tony Lindgren wrote:
>>> shrdram2: memory@10000 {
>>> device_type = "memory";
>>> reg = <0x10000 0x3000>;
>>> };
>> Shared RAM is not so straight forward. Both PRU firmwares and both application drivers
>> might need to read/write here. The area split is decided by firmware design and there
>> is no hardware protection to prevent from stomping on each others toes.
>> We need a carveout based memory allocator at least I think that can do a
>> allocate(base_offset, size); into shared RAM.
>> This could be used by pru_rproc driver at firmware load time and by application drivers
>> at initialization time.
>> Thoughts?
> That sounds sane to me :)
>>> If the ti,pruss-gp-mux-sel and ti,pru-interrupt-map are
>>> firmware configuration options, maybe leave them out of
>>> the dts completely and make the app-node optional.
>> Yes the app-node is optional. I will mention it.
>> No, ti,pruss-gp-mux-sel and ti,pru-interrupt-map are not firmware options.
>> But these settings are application/firmware specific.
>> ti,pru-interrupt-map specifies the configuration to be used for the INTC interrupt
>> controller.
> OK. So just to see if we have a standard solution available already..
> It sounds a bit similar to what we're doing with omap-wakeupgen.c
> and stacked interrupts? I wonder if something similar might help
> here?
>> ti,pruss-gp-mux-sel is used to configure this register.
>> "Table 30-20. PRUSS_GPCFG0" in
>> "29:26 PR1_PRU0_GP_MUX_SEL"
>> It configures how the pins from the PRUSS module are routed internally
>> to the various modules.

Actually, that's not entirely accurate. This is an internal pinmux (not
controllable per pin, but rather dictates a different sets of groups of
pins at the PRUSS boundary, which are then again multiplexed at the SoC
level using the standard padconf/pinmux. It is a single register per
core into which you can set some values between 0 through 4 IIRC
(unfortunately the values are also not uniform across the various SoCs).


>> see "30.2.1 PRU-ICSS I/O Interface"
>> and "Table 30-1. PRU-ICSS1 I/O Signals"
> Well these are external signals for PRUSS processor (although not
> necessarily external signals for the SoC). So why not handle them
> with a standard pinctlr binding with #pinctrl-cells?
> Sure it may not even be the Linux pinctrl framework running on the
> main SoC handling these pins, but after all you're describing
> hardware for a processor. Maybe Linus W has some comments on this?
> Regards,
> Tony