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From: John Baldwin <jhb@freebsd.org>
To: lev@freebsd.org
Subject: Re: Intel D2500CC motherboard and strange RS232/UART behavior
Date: Wed, 10 Apr 2013 10:20:34 -0400
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Cc: Adrian Chadd <adrian@freebsd.org>, freebsd-current@freebsd.org,
 Poul-Henning Kamp <phk@phk.freebsd.dk>
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On Wednesday, April 10, 2013 2:28:38 am Lev Serebryakov wrote:
> Hello, John.
> You wrote 10 =E0=EF=F0=E5=EB=FF 2013 =E3., 0:58:22:
>=20
> >>   Problem is, that every uart device now is independent from each
> >>   other in good "OOP" style, and it looks like interrupt sharing we
> >>   need one interrupt handler per irq (not per device), which will now
> >>   about several UARTs. Something like "multiport" device, bot not
> >>   exactly.
> JB> No, the interrupt code itself will handle shared interrupts (it will
> JB> call all handlers).  I think in practice that uart is setting
>   And what will happen, if there is two UARTs asserting interrupt in
> same time? First one returns "FILTER_HANDLED", will second handler be
> called?

They are all called in turn.

>   ISA interrupt sharing IS NOT so simple. sio contains a lot of
>  obscure code to work.

INTR_FAST handlers in 4.x didn't use to allow sharing.  That changed
in 6.x or so.

> JB> INTR_EXCL or some such and/or uart doesn't set RF_SHAREABLE when
> JB> allocating the IRQ.  It is probably the latter.  You could try just
> JB> adding RF_SHAREABLE to the bus_alloc_resource_any() for the IRQ to
> JB> uart and see if that fixes it.
>         sc->sc_ires =3D bus_alloc_resource_any(dev, SYS_RES_IRQ, &sc->sc_=
irid,
>             RF_ACTIVE | RF_SHAREABLE);
>=20
> It is here.

Ok, then you need to figure out what is actually failing to install an
interrupt handler (e.g. does bus_alloc_resource or bus_setup_intr fail?)

=2D-=20
John Baldwin