Re: [ECOS] hal_diag serial driver: using XON/XOFF flow control?

[Heiko Panther <heiko dot panther at web dot de>]

> > Am I overlooking something? If not, I would like to implement
> > XON/XOFF for the HAL diag driver. Looks like getting the received
> > character to the serial driver needs some architectural change in
> > the common HAL. Am I better off with reimplementing flow control
> > inside the hal diag driver? What do you suggest?
>
> The HAL serial support is intended solely for polled IO in RedBoot and
> for diagnostic output. If you want to have an interrupt driven, flow
> controlled serial device then implement a proper device driver, don't
> try to hack the HAL driver. There is plenty of documentation on how to
> do this and there are plenty of example in the source repository.

I now believe the simple answer to my question is: "Implement the XON/XOFF flow control inside the HAL driver."

Reason: If I enable CTRLC-Interrupts, I accept that all other received characters are lost. So I don't need to buffer anything, just look for XON/XOFF in addition to CTRLC. The character send routine then spins while TX is throttled (as the hardware flow control would do).

The code can go into the cyg_hal_plf_serial_getc_nonblock() routine, so it works for both polling and interrupt operation. It should not be neccessary to put the XON/XOFF through to /dev/haldiag, because it doesn't do buffering anyway, so it wouldn't help to let it know.

Heiko

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