On Fri, 2 Jun 2006 15:44:35 -0700 Greg KH <[EMAIL PROTECTED]> wrote: | On Fri, Jun 02, 2006 at 03:41:21PM -0700, Pete Zaitcev wrote: | > On Fri, 2 Jun 2006 13:50:14 -0700, Greg KH <[EMAIL PROTECTED]> wrote: | > > On Fri, Jun 02, 2006 at 12:03:14AM -0300, Luiz Fernando N.Capitulino wrote: | > | > > > 2. The new pl2303's set_termios() can (still) sleep. Serial Core's | > > > documentation says that that method must not sleep, but I couldn't find | > > > where in the Serial Core code it's called in atomic context. So, is this | > > > still true? Isn't the Serial Core's documentation out of date? | > > | > > If this is true then we should just stop the port right now, as the USB | > > devices can not handle this. They need to be able to sleep to | > > accomplish this functionality. | > > | > > Russell, is this a requirement of the serial layer? Why? | > | > Shouldn't it be all right to schedule the change at the moment of | > that call and have it happen later? Resisting a temptation to abuse | > keventd and schedule_work and using a tasklet may help with latency | > enough to make this tolerable. | | Some devices require more than one usb message to set all of the proper | termios bits in the device. Creating a way to queue them up and fire | them off later, and handle errors if something happened in the middle, | after we told userspace the termios change succeeded, might get quite | messy :(
But set_termios() returns nothing, and look what termios man page says about tcsetattr() return value: """ Note that tcsetattr() returns success if any of the requested changes could be successfully carried out. Therefore, when making multiple changes it may be necessary to follow this call with a further call to tcgetattr() to check that all changes have been performed successfully. """ Also, why do they need to sleep? Did you note that my version of set_mctrl() is atomic? -- Luiz Fernando N. Capitulino _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
