From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Lawyer Subject: Re: serial port speeds >115k; PnP modem ID must contain modem substring Date: Sun, 23 Feb 2003 23:11:36 -0800 Sender: linux-serial-owner@vger.kernel.org Message-ID: <20030224071136.GA495@lafn.org> References: <20030221200939.GA1543@jats9> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from localhost (mail@host-66-81-195-49.rev.o1.com [66.81.195.49]) by zoon.lafn.org (8.12.3/8.11.3) with ESMTP id h1O7OJ9D062835 for ; Sun, 23 Feb 2003 23:24:19 -0800 (PST) (envelope-from dave@lafn.org) Received: from dave by localhost with local (Exim 3.36 #1 (Debian)) id 18nCm0-00008T-00 for ; Sun, 23 Feb 2003 23:11:36 -0800 Content-Disposition: inline In-Reply-To: List-Id: linux-serial@vger.kernel.org To: linux-serial@vger.kernel.org On Sun, Feb 23, 2003 at 09:59:57PM -0800, rich+ml@lclogic.com wrote: > 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. 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? > > == Rich > > On Fri, 21 Feb 2003, Tim wrote: > > > Date: Fri, 21 Feb 2003 15:09:39 -0500 > > From: Tim > > To: linux-serial@vger.kernel.org > > Subject: serial port speeds >115k; PnP modem ID must contain modem > > substring > > > > I have a Diamond/Supra v90 ISA modem (model SUP2124) in my > > Linux system running 2.4.20. I've noticed that for the > > type of file I commonly access (large html text table) 115k > > port speed seems to be a significant bottleneck. (These > > files compress to <10% of raw size. Transfer speed is > > reported as ~10.5kByte/s, even if I reduce my modem speed > > from the typical 45kbps to 28.8.) The modem documentation > > says it is capable of 230k port speed, so I tried specifying > > 230400 in my ppp config, which resulted in 9600 baud port > > speed; stty returns an error. > > > > At this point in my education, my guess is that the modem is > > being treated like a 16550A without extended FIFOs or 230k > > port speed. If my modem was detected as a modem by Linux, > > would setserial -a show something more? > > > > # setserial -a /dev/ttyS3 > > /dev/ttyS3, Line 3, UART: 16550A, Port: 0x02e8, IRQ: 10 > > Baud_base: 115200, close_delay: 50, divisor: 0 > > closing_wait: 3000 > > Flags: spd_normal skip_test > > > > I am not a programmer, but have been looking at the comments > > in serial.c: > > > > There seems to be an ISA PnP device device search, the success > > of which depends on finding the string "modem" in PnP id: > > dev->name or dev->bus->name must contain "modem" substring; > > > > However, the modem in this system was installed with PnP > > disabled and does not have modem in its string: > > # ANSI string -->SupraExpress 56i Voice<-- > > > > What are the consequences of failing this test? If the > > string were changed, could the test succeed with the modem > > jumper not in PnP mode? > > > > 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? > > > > I now have CONFIG_SERIAL=y. > > If I compile serial as a module, are there parameters that > > can be added to modules.conf to enable available features > > beyond what a 16550A has, or perhaps someone has patches > > that would enable these features? > > > > TIA, > > Tim. > > > > - David Lawyer