On Tue, 6 Dec 2011, Geert Uytterhoeven wrote:
> Hi Finn,
>
> On Tue, Dec 6, 2011 at 16:13, Finn Thain <fthain@xxxxxxxxxxxxxxxxxxx> wrote:
> > +static void pmz_interrupt_control(struct uart_pmac_port *uap, int enable)
> > +{
> > + if (enable) {
> > + uap->curregs[1] |= INT_ALL_Rx | TxINT_ENAB;
> > + if (!ZS_IS_EXTCLK(uap))
> > + uap->curregs[1] |= EXT_INT_ENAB;
> > + } else {
> > + uap->curregs[1] &= ~(EXT_INT_ENAB | TxINT_ENAB | RxINT_MASK);
>
> Should there be a call to zssync() here?
I don't think so. Though I should have mentioned the change in the patch
header.
> The old code always did that after disabling interrupts.
pmz_load_zsregs(), pmz_set_termios() and pmz_suspend() don't do it.
sunzilog only does it on sparc64 and only when writing to the data
register or writing command modifiers to the control register ("On 64-bit
sparc we only need to flush single writes to ensure completion.")
I can't find any purpose for control register reads in the chip manual.
The zssync() calls following some WR1 writes originate here:
http://git.kernel.org/?p=linux/kernel/git/tglx/history.git;a=commitdiff;h=9e9d9f693c7def3900725c04c6b64311655eea51
So I don't see any need for control register reads but hopefully Ben can
say for sure.
Reading the patch now I notice that I dropped a pmz_maybe_update_regs() or
pmz_load_zsregs() in the suspend path. I will send a new patch.
Finn
>
> > + }
> > + write_zsreg(uap, R1, uap->curregs[1]);
> > +}
> > +
> > static struct tty_struct *pmz_receive_chars(struct uart_pmac_port *uap)
> > {
> > struct tty_struct *tty = NULL;
> > @@ -339,9 +351,7 @@ static struct tty_struct *pmz_receive_ch
> >
> > return tty;
> > flood:
> > - uap->curregs[R1] &= ~(EXT_INT_ENAB | TxINT_ENAB | RxINT_MASK);
> > - write_zsreg(uap, R1, uap->curregs[R1]);
> > - zssync(uap);
>
> Cfr. e.g. here.
>
> > + pmz_interrupt_control(uap, 0);
> > pmz_error("pmz: rx irq flood !\n");
> > return tty;
> > }
>
> Gr{oetje,eeting}s,
>
> Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
> -- Linus Torvalds
>
