Subject: Re: com.c patch to track PPS
To: Bill Studenmund <>
From: Jonathan Stone <jonathan@DSG.Stanford.EDU>
List: tech-kern
Date: 02/06/2000 21:48:24
In message <>
Bill  Studenmund writes:

>One problem I saw with what I suggest, which is present both in the older
>com driver and in the MI zs driver, is the
>		if (ISSET(~rr0, cs->cs_rr0_mask)) {
>line (snippet taken from the zs driver). It's in the delta code, and drops
>transmission if any of the bits in cs_rr0_mask are cleared.
>Given the case of transmitting when DCD is asserted, that's wrong.

Isn't DCD active low?  There was some confusion over what "assert"
means, the PPS-api says "assert" is when you have carrier.

But yep, thats one reason I left the sc_msr_mask alone.  The other is
that I think the com driver takes interrupts for DCD changes even if
MSR_DCD is off in sc_msr_mask.

>What I think we really need is:
>a mask of bits we care about for PPS - (sc_ppsmask for com, zst_ppsmask
>	for zs)
>a mask of bits we want interrupts for - (sc_msr_mask for com, cs_rr0_mask
>	for zs)
>a mask of bits we use for flow control - currently overloaded to the
>	above.

Very close :->. Looks like our messages crossed.