On Tue, Jun 25, 2013 at 11:54:37AM +0200, Reinhard Max wrote: > Hi Greg, > > coincidentally, I also tested non-standard baudrates on a PL2303 > these days and was about to start a similar thread when I found this > one... > > On Fri, 14 Jun 2013 at 18:58, Greg KH wrote: > > >On Fri, Jun 14, 2013 at 11:20:01AM +0200, Mastro Gippo wrote: > > > >>PS: this device (at least mine) WILL support 250K baudrate, as > >>in windows I can set it in any software I use, and the output is > >>spot on, measured with a digital oscilloscope. > > > >That's good to know, which model is it? Remember, the pl2303 > >driver supports at least 3 generations of this chipset (maybe 4). > >All of them seem to work just a little bit differently. > > I've tested[1] 250kBaud and even some strange baud rates such as > 345678 and 777777 on a PL2303HX based device and got plausible > numbers (same percentage off as nearby standard rates) when > measuring the time it takes to send and receive 1000 bytes after > through a RX/TX loop. > > This looks to me like at least the HX variant does support arbitrary > baud rates and it definitely doesn't fall back to 9600 as stated in > the comment above the rounding loop. > > So, how about starting to get rid of the baud rate list by skipping > it for HX chips only until someone with a type_0 or type_1 devices > can confirm that it works there as well? How about getting some of those devices and testing it? That's the best way to do it, right? After that, patches are always gladly accepted. > BTW, newer revisions of the things that Prolific calls datasheets > have a note next to the baud rate list that says, "For special baud > rate requirements, please contact Prolific FAE for driver > customization support.", which I take as a confirmation that the > limit to standard rates is only imposed by the driver. Can you get the "real" specs from them that show the differences and how to talk to the chips properly? That would be the best, otherwise, we are just guessing, like we have for the past 10+ years, as to how this chipset works... thanks, greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
