Re: [hpoj-devel] patch to improve scan speed/robustness

[Gerhard F. <ger...@fu...>]

David Paschal wrote:

> That's most likely the fault of the lower-level code.
> In order to support multiple instances of xojpanel or other PML
> clients, there needs to be a mechanism for multiplexing PML requests
> from different clients and routing
> the replies correctly.  Currently, starting up a second PML client
> attempts to open a second PML connection to the peripheral.
> ieee12844.c either doesn't properly handle the peripheral's refusal
> of the second open, and/or it doesn't properly handle multiple
> simultaneous opens period.  The latter is likely
> because I've gotten into trouble before while playing around
> with the scan and echo channels at the same time.

David,

can you remember the problem with MLCConfigSocket?
If a 2nd connection to the same peripheral port was attempted, then
ieee12844.c sent a 2nd MLCConfigSocket although this violates the
protocol. Therefore the 2nd connection to the same peripheral port
always failed.
The driver should remember to which ports it already has sent
MLCConfigSocket and also the negotiated parameters, and should not
send it at the 2nd connect attempt.
Do you remeber: Some time ago you told me about the problem, and I told
you, that I know, but that I hadn't it implemented yet.
Do you have already fixed this problem?

But even if this problem is fixed, then I'm not sure whether the
OfficeJet will a) accept a 2nd simultaneous PML connection and b)
whether the OJ will correclty multiplex the PML requests/responses/traps
over the two connections. According to the PML spec one could assume,
that PML devices _are_ generally capable to do this. But I wouldn't
believe it before I've seen that it works ...
If it works (with all OJ models), then maybe you can omit a separate PML
multiplexor on the host, if not, then you will definitely need it.

Gerhard

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