Alan wrote:
> > There are three different fixes:
> > 1. Fix for THRE errata
>
> That should be handled anyway. The current code actually spots this and
> uses a backup timer for dodgy UARTS
Thanks, I'll retest without this fix on the current l-m.o git master and see
if it still solves our errata.
> > 2. Fix for Busy Detect on LCR write
> > 3. Workaround for interrupt/data concurrency issue
>
> > case UPIO_MEM:
> > +#ifdef CONFIG_PMC_MSP
> > + /* Save the LCR value so it can be re-written when a
> > + * Busy Detect interrupt occurs. */
> > + if (dwapb_offset == UART_LCR)
> > + up->dwapb_lcr = value;
> > +#endif
> > writeb(value, up->port.membase + offset);
> > +#ifdef CONFIG_PMC_MSP
> > + /* Re-read the IER to ensure any interrupt disabling has
> > + * completed before proceeding with ISR. */
> > + if (dwapb_offset == UART_IER)
> > + value = serial_in(up, dwapb_offset);
> > +#endif
> > break;
>
> This I would hope you can hide in the platform specific
> serial_in/serial_out functions. If you write the UART_LCR save it in
> serial_out(), if you read IER etc.
I couldn't find hooks for platform specific serial_in/out functions.
Do you mean using the up->port.iotype's in serial_in/out from 8250.c?
>
> > +#ifdef CONFIG_PMC_MSP
> > + } else if ((iir & UART_IER_BUSY) == UART_IER_BUSY) {
> > + /*
> > + * The MSP (DesignWare APB UART) serial
> subsystem has a
> > + * non-standard interrupt condition (0x7) which
> means
> > + * that the LCR was written while the UART was
> busy, so
> > + * the LCR was not actually written. It is
> cleared by
> > + * reading the special non-standard extended
> UART status
> > + * register.
>
> Ditto... spot this case and whack it in your serial methods.
A serial_in(up, UART_IIR) calls occur in more places that just the interrupt
handler (i.e. autoconfig*, serial8250_start_tx, etc). We will need to check
if we are in an interrupt on each IIR read, hopefully that won't be too much
overhead!
>
> And we might want to add a void * for board specific insanity to the 8250
> structures if we really have to so you can hang your brain damage
> privately off that ?
Sounds good to me, it would give us a location to store the address of the
UART_STATUS_REG required by this UART variant.
Marc
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