From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tim Subject: port speeds >115k Date: Mon, 24 Feb 2003 12:57:38 -0500 Sender: linux-serial-owner@vger.kernel.org Message-ID: <20030224175738.GA349@jats9> References: <20030224071136.GA495@lafn.org> <20030221200939.GA1543@jats9> <20030221200939.GA1543@jats9> <20030221.235743.8.0.whitnl73@juno.com> <20030222092008.GA492@lafn.org> <20030221200939.GA1543@jats9> <20030221224119.GD350@lafn.org> <20030221200939.GA1543@jats9> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20030222092008.GA492@lafn.org> <20030221.235743.8.0.whitnl73@juno.com> <20030221224119.GD350@lafn.org> <20030221200939.GA1543@jats9> <20030223104525.A206@lnx2.w8mch.ampr.org> <20030224071136.GA495@lafn.org> List-Id: linux-serial@vger.kernel.org To: linux-serial@vger.kernel.org [cc's not required] > > > stty returns an error. > > > > What error? Quote exactly please. stty -F /dev/ttyS3 230400 stty: /dev/ttyS3: unable to perform all requested operations > > If the doco says it can run faster than 115200, it should also tell > > what you have to do to make it do so. > > Yes. It will likely say (or imply) to use a driver they supply for > Windows only. ^^^^^^^^^^^ Ha! ~"All our 56k modems are capable of supporting 230k ... go find a driver from someone else", actually. Or try to ID the chipset & find the datasheet. > > > If my modem was detected as a modem by Linux, > > > would setserial -a show something more? > > > > It was detected as a serial port. Linux does not detect modems at > > startup. I guess all that modem stuff in serial.c is just for PnP addr/irq init. > > There seems to be a "quickie test to see how big the FIFO is". > > How can I cause the results of that test to be logged? > Is this test done by some Linux utility? grep quickie drivers/char/serial.c > > Internal modems usually just have a simulated uart for software > > compatibility and baud rate is irrelevant (same for parity, stop bits, > > FIFO, etc). Set to 5 baud and see if you get same performance. Well I noticed stty makes no dif in an xterm, or the getty on a vc, but with http://members.gate-way.net/delt/test/500k.html my hardware ISA modem behaves like: CARRIER PORT AVG.RATE ======= ==== ======== 46k 115k 10.5kB/s 26k 115k 10.5kB/s 14k 115k 10.5kB/s 46k 57k 5.3kB/s For viewing large html text tables with a fast browser like Dillo, 230k could ~double the speed of the whole process. > I set to 300 baud and couldn't connect. Then at 1200 baud it connected but > download speeds were around 60 bytes/sec. I estimated the received rate > from the /proc dir and it was close to 1200 baud. So mine must have a > real UART. > > Some modems brag that they can do 230.4k baud. This is a serial port > speed. So it seems like a real UART. So what percent of internal > modems will operate at a high baud rate when one specifies low baud rate? I've seen non-rigorous test results on the net indicating that some softmodems have no port-speed bottleneck. It'd be great to have a GPL HSP modem for Linux, now that GHz CPUs are the norm. This groveling for 230kbits/s through a device sitting directly on the system bus, and being hobbled by hostile hw/sw producers is hard to take. Wonder what the absolute minimum hardware for a modem is...