Subject: Re: Totally broken change to com.c
To: None <firstname.lastname@example.org>
From: Onno van der Linden <email@example.com>
Date: 10/18/2001 00:03:21
Charles M. Hannum <firstname.lastname@example.org> wrote:
> So, I'm looking at this, and there are two obvious problems:
> bus_space_write_1(iot, ioh, com_ier,sc->sc_ier)
> - iir = IIR_NOPEND;
> You can't do this. In that case where that kluge fires (a bug in some
> Winbond chips), it will cause the go to go into a loop and wedge.
> This change *must* be removed.
Maybe I'm completely missing something here. As far as I know the continue
causes the code to go to the end of the do while loop where we get
> ! } while (ISSET((iir = bus_space_read_1(iot, ioh, com_iir)), IIR_RXRDY)
> ! || ((iir & IIR_IMASK) == 0));
> This test is also wrong. The IIR is *NOT* a bit mask. Please read
> the documentation.
And here, iir is set again via the bus_space_read_1() and thus overwriting
the IIR_NOPEND from before the continue statement. So, if the
iir = IIR_NOPEND bit is meant as a no-op or delay to fix a winbond uart bug
it probably should have a comment as to why it is there.
The ((iir & IIR_IMASK) == 0) could/should be ((iir & IIR_IMASK) == IIR_MLSC).
Now, if only I had saved the email discussions I exchanged with Allen Briggs
about his broken uart and how to fix it, this respons would be somewhat