[Nut-upsdev] Fwd: Megatec - modem control lines [impact to megatec_usb]

[Carlos Rodrigues]

Hi,

Sorry for the forwarding. I sent this with the wrong "from" address
and got rejected by the list.

---------- Forwarded message ----------
From: Carlos Rodrigues <cefrodrigues at mail.telepac.pt>
Date: Jun 18, 2007 9:34 PM
Subject: Re: Megatec - modem control lines [impact to megatec_usb]
To: Arjen de Korte <nut+devel at de-korte.org>
Cc: ups-dev-list <nut-upsdev at lists.alioth.debian.org>


On 6/18/07, Carlos Rodrigues <carlos.efr at mail.telepac.pt> wrote:
> On 6/18/07, Arjen de Korte <nut+devel at de-korte.org> wrote:
> > So far, the megatec driver doesn't do anything with the modem control
> > lines at all. This may be OK if these are indeed not used by the
> > interface (for instance if only TX and RX are wired). But if they are
> > used to provide cable power this is not right. The build in NUT
> > functions don't do anything with the modem control lines and will leave
> > them in the state they are in before the driver started. If that happens
> > to be the right state, fine, but if they are not, we have a problem.
> > Therefor, I want to propose the following patch:
> >
> [snip]
> >
> > This should be backwards compatible, since we never did anything with
> > these lines before, so the state would have been 'random' until now.Note
> > that at power up, these often will be cleared so usually they will be
> > cleared, but if the port had been used before by other applications, the
> > state they're in is undefined.
> >
> > The least this patch will do, is to define a state for the modem control
> > lines.
>
> Well, in principle I don't have a problem with this. I'll test it
> later at night.

Ok, I've tested it and it seems ok. However, this needs to be done in
a way that doesn't hurt megatec_usb, so I don't think it is a good
idea to add this to the trunk as is.

--
Carlos Rodrigues



-- 
Carlos Rodrigues
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