From: Dave Taht <dave.taht@gmail.com>
To: esr@thyrsus.com
Cc: thumbgps-devel@lists.bufferbloat.net,
Andrew McGregor <andrewmcgr@gmail.com>
Subject: Re: [Thumbgps-devel] USB handshake signals and Linux
Date: Wed, 14 Mar 2012 11:57:06 -0700 [thread overview]
Message-ID: <CAA93jw55jC9F4Dtsp9Nf74R3AFg8SisBZE=X_UD+i38Ckf6SEA@mail.gmail.com> (raw)
In-Reply-To: <20120314184258.GA30210@thyrsus.com>
On Wed, Mar 14, 2012 at 11:42 AM, Eric S. Raymond <esr@thyrsus.com> wrote:
> Patrick Maupin <pmaupin@gmail.com>:
>> The FTDI devices have a latency timer that allows you to control this
>> somewhat.
>
In a private chat late last night andrew mentioned that the ftdi devices
were extensively reprogrammable, in that they came as a usb device
but were really, underneath, just a bunch of gpios...
> I found a couple of hits on the search "PL2303 latency timer" that
> implies it has one too. But I doubt the value of the latency timer
> will be relevant for handshake-line notifications; see below.
>
>> But even better, if we're going to use the PPS signal, they
>> essentially guarantee that they will send ASAP on modem control signal
>> change. We might need to characterize "ASAP" but I would hope that it
>> doesn't vary too much.
>
> Probably not. Trying to buffer a handshake state change doesn't make
> any sense. I'm not surprised that the FTDI gives them realtime
> priority and I *will* be surprised if the PL2303 (or any other
> adapter) doesn't do likewise.
> --
> <a href="http://www.catb.org/~esr/">Eric S. Raymond</a>
> _______________________________________________
> Thumbgps-devel mailing list
> Thumbgps-devel@lists.bufferbloat.net
> https://lists.bufferbloat.net/listinfo/thumbgps-devel
--
Dave Täht
SKYPE: davetaht
US Tel: 1-239-829-5608
http://www.bufferbloat.net
next prev parent reply other threads:[~2012-03-14 18:57 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-14 10:49 Eric S. Raymond
2012-03-14 12:55 ` Ron Frazier (NTP)
2012-03-14 12:58 ` Ron Frazier (NTP)
2012-03-14 18:13 ` Patrick Maupin
2012-03-14 18:42 ` Eric S. Raymond
2012-03-14 18:57 ` Dave Taht [this message]
2012-03-14 20:09 ` Patrick Maupin
2012-03-15 3:33 ` Patrick Maupin
2012-03-15 4:23 ` Eric S. Raymond
[not found] <CAFv7OigTLhw24i+jRshv0YgLogyx_GEREAOkP7tieeH1Nr5WzA@mail.gmail.com>
2012-03-15 14:37 ` tz
2012-03-15 14:52 ` Ron Frazier (NTP)
2012-03-15 17:57 ` Eric S. Raymond
2012-03-15 18:31 ` Eric S. Raymond
2012-03-15 18:54 ` Patrick Maupin
2012-03-15 19:36 ` Eric S. Raymond
2012-03-15 19:55 ` Patrick Maupin
2012-03-15 19:14 ` tz
2012-03-15 19:50 ` Eric S. Raymond
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