[PATCH rtems-libbsd] rtemsbsd: Use a separate header for test devices

[Kinsey Moore]

On 7/8/2021 19:43, Chris Johns wrote:
> On 9/7/21 7:32 am, Kinsey Moore wrote:
>> On 7/8/2021 10:36, Kinsey Moore wrote:
>>> The solutions to the remainder of the problem are:
>>>
>>> 1) Use a different, smarter PHY driver and avoid use of ukphy when multiple
>>> interfaces are present
>>>
>>> ** This could possibly solve the general problem for ethernet interfaces and
>>> replace the ukphy driver for new multi-interface hardware
>>>
>>> ** Lets nexus-devices.h contain all interfaces that exist on the hardware,
>>> possibly applicable to Zynq7000 and versal as well
> The problem here is some PHYs are covered by NDAs and a PHY that uses just the
> IEEE defined registers, ie UKPHY, is a good solution for a number of cases.
>
> I do not think the PHY drivers are the issue here.
Now that I've had time to identify the root cause of the spurious PHY 
detections, I agree. I thought I had seen the PHY presence detection 
code in ukphy when it was actually in mii.c.
>>> 4) Embed FDT somewhere that defines what interfaces get configured
>>>
>>> ** Pulls in extra dependencies
>>>
>>> ** Doesn't solve the test issue without generation/embedding of a FDT
>>>
>>> ** Allows the application to have exactly what it wants via a relatively
>>> standard mechanism
>>>
>>> ** Lets nexus-devices.h contain all interfaces that exist on the hardware,
>>> possibly applicable to Zynq7000 and versal as well
> I wonder if it is worth considering how a user would add and remove interfaces
> using this approach before we head down this path?
Eventually having this path as an option would be nice, but I don't 
think that it should be required and thus is a non-starter for basic 
functionality.
>>> I'm starting to lean toward option #1. It allows all interfaces to be defined
>>> and the primary interface for testing can be selected by the existing test
>>> configuration in config.inc. Applications can check the available interfaces
>>> for connectivity or they can prune the nexus devices in their own copy instead
>>> of pulling in nexus-devices.h.
>> I looked a little further into what it would take to make a smarter version of
>> ukphy and ukphy isn't actually the issue here. The code in mii.c that detects
>> whether a PHY exists at all has a bug in it where PHY read timeouts aren't
>> detected and handled and so the 0xffffffff result of the failed read slips
>> through the bad-PHY check. I'm working up and verifying the patch for that now.
>> Fixing that should hopefully allow for all interfaces to be enabled without issue.
> The mii.c only comes into play when the probe passes and we are attaching the
> device.
>
> I was thinking of a MII probe call ...
>
> #if __rtems__
> int mii_probe()
> {
>    for (phy = 0; phy < 31; phy++) {
>      WR4(sc, CGEM_PHY_MAINT,
>        CGEM_PHY_MAINT_CLAUSE_22 | CGEM_PHY_MAINT_MUST_10 |
>        CGEM_PHY_MAINT_OP_READ |
>        (phy << CGEM_PHY_MAINT_PHY_ADDR_SHIFT) |
>        (reg << CGEM_PHY_MAINT_REG_ADDR_SHIFT));
>
>      /* Wait for completion. */
>      tries=0;
>      for (tries = 0; tries < 5; ++tries) {
>        if ((RD4(sc, CGEM_NET_STAT) & CGEM_NET_STAT_PHY_MGMT_IDLE) != 0) {
>          return OK;
>        }
>        DELAY(2);
>      }
>    }
>    return NOT_FOUND;
> }
> #endif
>
> This only works if the MAC can be accessed this early in a boot and dos not need
> anything else to be enabled. Maybe the enables are easy as well, I have not looked.
>
> For an interface with no PHY and not being used the MII probe delay is 192msec
> which I think is just OK, maybe (??), but more than I would like.

I have a patch set just about ready that resolves the test configuration 
leakage, resolves the issue in mii.c that's causing spurious PHY 
detection (and the interfaces with no PHYs go away because they fail to 
attach), and resolves another bug with the default network test 
configuration exposed by having multiple interfaces with the functional 
one being later in the sequence. Only the functional interface(s) appear 
in the output of ifconfig.


Kinsey