Re: [coldsync-hackers] coldsync 1.5.3 nov 27 snapshot

[Andrew Arensburger <arensb+CShackers@ooblick.com>]

On Wed, 29 Nov 2000, Greg KH wrote:
> On Wed, Nov 29, 2000 at 08:21:44PM -0500, Andrew Arensburger wrote:
> > 	Yeah, you're going to continue seeing "Bad CRC" errors under Linux
> > until the serial device is fixed (or until you comment out that fprintf()
> > :-) ). When it gets a malformed packet like that, ColdSync doesn't
> > acknowledge it and waits for the Palm to resend it, just as it's always
> > done.
> 
> Hm, I'm all ears as to what needs to be fixed in the Linux serial driver :)
> 
> Seriously, what's the problem?  Why do you think that the serial driver
> (or the usb visor) driver drops bytes at the beginning?

	It's not the USB driver: I've gotten this on the plain old serial
port.
	In brief, ColdSync (and pilot-link) under Linux appear to get a
lot of dropped characters from the serial port. I'm afraid to look at the
pilot-link source, but all ColdSync does is
	open()
	cfsetspeed(B9600)
	cfmakeraw()
	cfsetspeed()
	read() and write()
	close()

	I haven't noticed any definite pattern to the dropped bytes; it's
not doing tab-expansion or CRLF->LF conversion. It did seem to me that the
dropped sequences were usually 1-3 bytes long; I didn't see any longer
than 5 or 6. At one point, there appeared to be a 16-byte period (i.e., it
would get 14 correct bytes, drop 2, get 14 more, drop 2, and so forth).
The value 0x0d appeared to be dropped more often than other values.
	(Bear in mind, however, that I am a homo sapiens; members of my
species are very good at noticing patterns even where there aren't any.)

> I'd be glad to fix this in the kernel, if that's what's needed.

	This might be a kernel problem. I took a brief glance, but didn't
stay long enough to go into full kernel-dive mode (besides, there's a huge
installed base with the current kernel, and I should cope with that). I
did see a comment that said something like, "If the user wants it raw,
turn off overrun checking as well". Dunno if that means anything, though.

-- 
Andrew Arensburger                      This message *does* represent the
arensb@ooblick.com			views of ooblick.com
Reading this posting obligates you to concur with all opinions therein.


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