Messages in this thread | | | Date | Tue, 17 Mar 2009 17:38:20 +0100 (CET) | From | Ralf Nyren <> | Subject | RE: Sierra Wireless (MC8780) HSDPA speed issue |
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Hi,
Three devices appear, ttyUSB0, ttyUSB1, ttyUSB2.
Response from ATI command is as follows:
ttyUSB0: (this is the device providing high speed connection) Sierra Wireless, Inc. MC8780 APP1
ttyUSB1: no response here, I understand this device is for the proprietary protocol...
ttyUSB2: (this is the device with the speed "problem") Manufacturer: Sierra Wireless, Inc. Model: MC8780 Revision: F1_0_0_10AP C:/WS/FW/F1_0_0_10AP/MSM7200R3/SRC/AMSS 2007/11/08 10:51:15 IMEI: 354219010190864 IMEI SV: 7 FSN: D332567166610 3GPP Release 6 +GCAP: +CGSM,+DS,+ES
From my experience there are very few commands which gives any output at all on ttyUSB0. AT+CSQ and AT+COPS? gives output on ttyUSB0 but commands like AT*CNTI=0 only give output on ttyUSB2.
Hope that's the information you're looking for.
Best regards, Ralf
On Tue, 17 Mar 2009, Rory Filer wrote:
> Hi Ralf, > > I wonder whether you could do a little experiment for me. Issue the following AT command to both ports you've identified: > > ATI > > And note which of the AT ports provides the most information. They will both respond, but one will be more verbose than the others. > > Another thing of interest is to record how many files appear in response to the following command: > > ls /dev/ttyU* > > when the modem is running, of course. > > Question - at what point should we stop including linux-kernel in this thread, if at all? > > Regards > > Rory > > -----Original Message----- > From: Ralf Nyren [mailto:ralf@nyren.net] > Sent: Tuesday, March 17, 2009 8:54 AM > To: Rory Filer > Cc: Greg KH; Stephen Clark; linux-kernel@vger.kernel.org; Kevin Lloyd > Subject: RE: Sierra Wireless (MC8780) HSDPA speed issue > > Hi again, > > Problem solved this time, well sort of anyway. > > This is a bit embarrassing, was quite sure I had tested this before but oh well... > > According to the FAQ at sierrawireless.com you should make the data connection > on /dev/ttyUSB2 when using a MC8780 modem, /dev/ttyUSB0 is used for AT commands > queries. This works nicely except for the speed problem. Now _changing_ so the > data connection is established on /dev/ttyUSB0 instead solves the speed > problem. I have successfully reached average download speeds above 400KB/s. > > Just to make sure I tried this fix using both 1.3.2 and 1.6.0 driver. I also > tried the modified ppp_async.c with OBUFSIZE=4096. The cell appeared to be > rather busy during the tests but as far as I can see both drivers and OBUFSIZE > gave about the same speed, i.e. 300-400KB/s at my current location. No issue > with the kernel that is. > > My only remaining problem is that I can't issue commands like AT+CSQ, AT+COPS? > to determine signal strength and ISP while the connection is up and running. > Any AT command sent to /dev/ttyUSB2 while pppd runs on /dev/ttyUSB0 causes an > immediate modem hangup. Not a big issue but it would be nice if it worked. > > The card is a builtin card in the laptop and all tests reported so far have > been performed with the same machine. Have a dual boot setup with Debian Lenny > and Windows XP. Firmware on the MC8780 card is reported as follows: > > AT+GMR > F1_0_0_10AP C:/WS/FW/F1_0_0_10AP/MSM7200R3/SRC/AMSS 2007/11/08 10:51:15 > OK > > If you think this problem could affect others as well an update to the table on > the FAQ page would be nice: > http://www.sierrawireless.com/faq/ShowFAQ.aspx?ID=607 > > Thanks for all valuable help and support. Just let me know if you need someone > to test future firmware/driver updates. > > Best regards, Ralf > > > On Mon, 16 Mar 2009, Rory Filer wrote: > >> Hi Ralf, >> >> Actually the Windows and Linux models are the same from the modem's point of view, but the PPP client is inside the NDIS driver. >> >> I've pasted in the response from our UMTS engineer below, but I'm not sure how much help it will be; here it is: >> >> -----Begin Included... >> There is no specific AT command that would limit the data rate on the device - except for AT!HSDCAT but I do not think that he would be using this. Other commands such as AT+CGEQREQ probably would not help, so they should clear them. >> >> From the email below it seems that he used the same device on Windows so the device configuration should be OK. The location could be an issue but I would assume that he tried using the device with Windows at the same location. >> >> One problem that I have seen with USB is that the USB modem throughput will be low if there are other devices on the same USB hub of the laptop >> ----End Included >> >> There it is. If you could get your hands on another machine and put Linux on it - or maybe temporarily make your windows machine into Dual Boot with Ubuntu (using wubi) and see how that compares that might help, but I am out of useful ideas at this point. >> >> Regards >> >> Rory >> >> >> >> -----Original Message----- >> From: Ralf Nyren [mailto:ralf@nyren.net] >> Sent: Monday, March 16, 2009 5:48 AM >> To: Greg KH >> Cc: Rory Filer; Stephen Clark; linux-kernel@vger.kernel.org; Kevin Lloyd >> Subject: Re: Sierra Wireless (MC8780) HSDPA speed issue >> >> Thanks Rory, >> >> I have tried changing OBUFSIZE in ppp_async.c (still kernel 2.6.28.7), first >> 512 and then 4096. However the speed "limit" of about 100KB/s remains the same. >> So perhaps there's some setup/firmware issue with the hardware. If I understand >> things correctly the Windows driver uses a proprietary protocol to init the card >> while in Linux you use the AT command interface. Could be something there which >> makes a difference I guess. >> >> Best regards, Ralf >> >> On Sun, 15 Mar 2009, Greg KH wrote: >> >>> On Sun, Mar 15, 2009 at 03:30:54PM -0700, Rory Filer wrote: >>>> Hi Ralf >>>> >>>> Using the driver we sent you on a call-box (i.e. with a "perfect" >>>> simulated network connection) on Ubuntu 8.04 we were seeing ~4 Mbps on >>>> the downlink. So I would rule out any problem with the driver and >>>> conclude it must be something in either PPP/Linux or in the modem. In >>>> order to rule out the modem, I've got a question into one of our UMTS >>>> engineers and will send you a reply when we get the answer. >>>> >>>> We did play around a little with 2.4 kernels of Linux and discovered >>>> there is a buffer in PPP_ASYNC.C which, when its size is increased, >>>> doubled the throughput. If you are savvy enough with Linux, you might >>>> want to try playing with that. We stopped short of any thorough >>>> testing of changing this array size, but were pleased with the result. >>>> If I recall properly, the size of this array is (was, in 2.4) 256 >>>> bytes. Doubling it gave an immediate improvement. We were guessing >>>> that the small size of this buffer was fine in the "old days" when >>>> modems peaked at ~56 kbps. Even 8 years ago that was the fastest you >>>> could go with a GPRS product, now our new HSPA+ products yields 21 >>>> Mbps on Telstra's network! Quite a difference. >>> >>> Ah, the OBUFSIZE #define in drivers/net/ppp_async.c? >>> >>> Anyone care to bump this size up and see if that helps out? >>> >>> thanks, >>> >>> greg k-h >>> >> >> > >
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