On Thu, 30 Sep 1999, Benjamin Herrenschmidt wrote:

I've heard of various possible issues with DMA hardware on the serial
ports and G3 macs. There seem to be a problem with the Heathrow
generation of Apple ASICs. (This was reported to me by people who made a
special device that was plugged into those ports, with a custom driver
under MacOS). They told me some characters end up beeing garbled when
reaching the SCC. I'll do some testings with your driver and my
powerbook's internal modem this week end to see if this problem actually
occurs or not.

I suppose that can happen if DBDMA's FIFO wasn't flushed properly for
some reason.  Do you know if the problem occurs on receiving side (from
SCC to DMA) or transmitting side (from DMA to SCC)?  How many chars were
garbled?  If the FIFO were the cause of the problem, the number should be
between 1 and 7.


Takashi Oe


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