Re: [PATCH] ptp: ocp: don't allow on S390

On Mon, Aug 16, 2021 at 02:15:51PM -0700, Randy Dunlap wrote:

On 8/16/21 2:09 PM, Jonathan Lemon wrote:

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On Fri, Aug 13, 2021 at 01:30:26PM -0700, Randy Dunlap wrote:

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There is no 8250 serial on S390. See commit 1598e38c0770.

There's a 8250 serial device on the PCI card.   Its been
ages since I've worked on the architecture, but does S390
even support PCI?

Yes, it does.

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Is this driver useful even without 8250 serial?

The FB timecard has an FPGA that will internally parse the
GNSS strings and correct the clock, so the PTP clock will
work even without the serial devices.

However, there are userspace tools which want to read the
GNSS signal (for holdolver and leap second indication),
which is why they are exposed.

So what do you recommend here?

Looking at 1598e38c0770, it appears the 8250 console is the 
problem.  Couldn't S390 be fenced by SERIAL_8250_CONSOLE, instead
of SERIAL_8250, which would make the 8250 driver available?

For now, just disabling the driver on S390 sounds reasonable.
-- 
Jonathan