From: abel deuring <adeur...@gmx.net> Subject: Re: [sane-devel] Re: Avision backend Date: Thu, 17 Jan 2002 20:34:55 +0100
> Rene Rebe wrote: > > > > > - hpusbscsi+sane+avision will not handle large transfers. It is > > > > necessary to > > > > use a large SANE_SG_BUFFERSIZE. Is it easy to fix? > > > > > > use sanei_scsi_open_extended instead of sanei_scsi_open. The former > > > function has one more parameter, the buffer size. On return, you should > > > check, if you got the buffer size you wanted. If > > > sanei_scsi_open_extended returns a too small value for your purposes, > > > you can call an appropriate DBG statement and return an error to the > > > caller. > > > > Ok. The only problem we have is: that the calibration data seems to > > get rather big (200kB - 400kB?) and it _seems_ that it has to be > > transfered with one SCSI command. (From the windows-log they seem to > > be also using a single command ...). I'm not such a SCSI freak - so is > > it possible to devide a SCSI command into single small ones? > > Theoretically, it should be possible to read/write data in smaller > chunks. OTOH, I remeber that Oliver Rauch increased the default SCSI > buffer size for, uuuhhh, was it Irix?, because some Umax scanner wants > to read or write something like calibration data in exactly one block. Hm. It seem that the Avision scanner want to transfer the data in one chunck too ... - I'll have a look on the win-driver trace again ... > But anyway, my point regarding sanei_scsi_open_extended was that this > function gives you better control over the buffer size, at least under > Linux. So, if the scanner allows to read/write the calibration data with > more than command, you can easily adjust the number of required commands > -- and if the scanner needs exactly SCSI command for the data, you can > avoid the usage of environment variable SANE_SG_BUFFERSIZE. Before the > Linux SG driver allowed to set the buffer size at run time, and before I > had set the default Sane buffer size to 128 kB, we had quite a few > questions on the meiling list, how to adjust the buffer size. So, if you > set the proper buffer size without using SANE_SG_BUFFERSIZE, you make > like easier for many users and you avoid some questions. I'll try to play with this, too. Thanks. > Abel > _______________________________________________ > Sane-devel mailing list > sane-de...@www.mostang.com > http://www.mostang.com/mailman/listinfo/sane-devel > k33p h4ck1n6 René -- René Rebe (Registered Linux user: #248718 <http://counter.li.org>) eMail: rene.r...@gmx.net r...@rocklinux.org Homepage: http://drocklinux.dyndns.org/rene/ Anyone sending unwanted advertising e-mail to this address will be charged $25 for network traffic and computing time. By extracting my address from this message or its header, you agree to these terms.
