On Wed, 21 Feb 2007 16:48:26 +0000, Alan <[email protected]> wrote:
> > +#ifdef CONFIG_CPU_TX49XX
> > + /* TX4925 BUG WORKAROUND. Accessing SIOC register
> > + * immediately after soft reset causes bus error. */
> > + iob();
> > + udelay(1);
> > +#endif
>
> Given this costs 1uS in a path that is not performance critical is it
> worth putting the #ifdef/#endif in instead of having one set of code that
> works for all ?
Thank you for review. I'll drop the #ifdef. Also I'll replace iob()
with mmiowb() since it is MIPS specific.
> > + while (sio_in(up, TXX9_SIFCR) & TXX9_SIFCR_SWRST)
> > + ;
>
> Suppose it doesn't clear ? Should also use cpu_relax() in busy loops
> so any processor variant with power management can do the right thing.
Then I'll put udelay() and a timeout counter for it. If udelay() was
in the busy loop, cpu_relax() is still recommended?
Here is a patch on top of the previous one. If this was OK I'll fold
it into one patch.
--- a/drivers/serial/serial_txx9.c
+++ b/drivers/serial/serial_txx9.c
@@ -277,16 +277,15 @@ static void serial_txx9_enable_ms(struct
static void serial_txx9_initialize(struct uart_port *port)
{
struct uart_txx9_port *up = (struct uart_txx9_port *)port;
+ unsigned int tmout = 10000;
sio_out(up, TXX9_SIFCR, TXX9_SIFCR_SWRST);
-#ifdef CONFIG_CPU_TX49XX
/* TX4925 BUG WORKAROUND. Accessing SIOC register
* immediately after soft reset causes bus error. */
- iob();
+ mmiowb();
udelay(1);
-#endif
- while (sio_in(up, TXX9_SIFCR) & TXX9_SIFCR_SWRST)
- ;
+ while ((sio_in(up, TXX9_SIFCR) & TXX9_SIFCR_SWRST) && --tmout)
+ udelay(1);
/* TX Int by FIFO Empty, RX Int by Receiving 1 char. */
sio_set(up, TXX9_SIFCR,
TXX9_SIFCR_TDIL_MAX | TXX9_SIFCR_RDIL_1);
-
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