Re: [linux-usb-devel] Question about usb-serial port registration

2007-03-24 Thread Oliver Neukum
Am Samstag, 24. März 2007 04:30 schrieb Alan Stern: > Regular files work like that.  If a program has a file named "foo" open > when you do "rm foo", the open file reference won't prevent you from > creating a new file named "foo" in the same directory.  There will be no > conflict or confusion

Re: [linux-usb-devel] Question about usb-serial port registration

2007-03-23 Thread Greg KH
On Fri, Mar 23, 2007 at 01:30:45PM -0700, John wrote: > > Those aren't serial numbers in the USB sense. > > > Consider any FT 232R device, which is assigned > > one from the factory > > I see. So, aparently, Till wanted to query > for the manufacturer's assigned serial number > and somehow rememb

Re: [linux-usb-devel] Question about usb-serial port registration

2007-03-23 Thread Alan Stern
On Fri, 23 Mar 2007, Greg KH wrote: > > I don't buy the argument about needing to keep the number in use merely > > because the device node is still open. Once the node has been > > unregistered it is no longer visible to userspace. Only the existing open > > file references can be used, and a n

Re: [linux-usb-devel] Question about usb-serial port registration

2007-03-23 Thread Greg KH
On Fri, Mar 23, 2007 at 11:30:16PM -0400, Alan Stern wrote: > On Fri, 23 Mar 2007, Greg KH wrote: > > > On Fri, Mar 23, 2007 at 12:36:11PM -0700, John wrote: > > > Here two solutions are possible: > > > 1. Keep port range (ttyUSB0 and ttyUSB1 in this case) > > > reserved until all files are closed

Re: [linux-usb-devel] Question about usb-serial port registration

2007-03-23 Thread Alan Stern
On Fri, 23 Mar 2007, Greg KH wrote: > On Fri, Mar 23, 2007 at 12:36:11PM -0700, John wrote: > > Here two solutions are possible: > > 1. Keep port range (ttyUSB0 and ttyUSB1 in this case) > > reserved until all files are closed. > > This is what the current code attempts to do. > > But this means t

Re: [linux-usb-devel] Question about usb-serial port registration

2007-03-23 Thread Greg KH
On Fri, Mar 23, 2007 at 07:18:50PM -0700, John wrote: > > --- Greg KH <[EMAIL PROTECTED]> wrote: > > > As for applications that foolishly use ttyUSB0 only, > > well, they kind of deserve the breakage. > > It is pretty trivial to work around that issue > > with udev if they want to (and it's rec

Re: [linux-usb-devel] Question about usb-serial port registration

2007-03-23 Thread John
--- Greg KH <[EMAIL PROTECTED]> wrote: > As for applications that foolishly use ttyUSB0 only, > well, they kind of deserve the breakage. > It is pretty trivial to work around that issue > with udev if they want to (and it's recommended > that they fix it that way...) In this case somebody sho

Re: [linux-usb-devel] Question about usb-serial port registration

2007-03-23 Thread Greg KH
On Fri, Mar 23, 2007 at 01:35:44PM -0700, John wrote: > > I say #1 as I implemented it :) > > > > If userspace still has the device node open, then we > > need to keep the > > number still in use. > > OK, if this behavior is by design > (and it is hard to tell what is by design > and what is by a

Re: [linux-usb-devel] Question about usb-serial port registration

2007-03-23 Thread John
> I say #1 as I implemented it :) > > If userspace still has the device node open, then we > need to keep the > number still in use. OK, if this behavior is by design (and it is hard to tell what is by design and what is by accident when you look at a code without any documentation), then I will

Re: [linux-usb-devel] Question about usb-serial port registration

2007-03-23 Thread Oliver Neukum
Am Freitag, 23. März 2007 21:18 schrieb David Brownell: > > > > It seems to me that if we cannot guarantee that > > > > the devices are identical, we must make sure they > > > > have different numbers. > > That means the numbers "x" in ttyUSBx will almost never > be re-used. To me that sounds lik

Re: [linux-usb-devel] Question about usb-serial port registration

2007-03-23 Thread John
> Those aren't serial numbers in the USB sense. > Consider any FT 232R device, which is assigned > one from the factory I see. So, aparently, Till wanted to query for the manufacturer's assigned serial number and somehow remember which ttyUSBx port we assigned to it and assign the same number nex

Re: [linux-usb-devel] Question about usb-serial port registration

2007-03-23 Thread Greg KH
On Fri, Mar 23, 2007 at 08:42:28PM +0100, Till Harbaum / Lists wrote: > Hi, > > Am Freitag, 23. M?rz 2007 20:36 schrieb John: > > It seems to me that if we cannot guarantee that > > the devices are identical, we must make sure they > > have different numbers. > What about devices that have serial

Re: [linux-usb-devel] Question about usb-serial port registration

2007-03-23 Thread Greg KH
On Fri, Mar 23, 2007 at 12:36:11PM -0700, John wrote: > Here two solutions are possible: > 1. Keep port range (ttyUSB0 and ttyUSB1 in this case) > reserved until all files are closed. > This is what the current code attempts to do. > But this means that if the same device is re-plugged, > it will b

Re: [linux-usb-devel] Question about usb-serial port registration

2007-03-23 Thread David Brownell
> > > It seems to me that if we cannot guarantee that > > > the devices are identical, we must make sure they > > > have different numbers. That means the numbers "x" in ttyUSBx will almost never be re-used. To me that sounds like something that will break lots of userspace code. > > What about

Re: [linux-usb-devel] Question about usb-serial port registration

2007-03-23 Thread Till Harbaum / Lists
Hi, Am Freitag, 23. März 2007 20:58 schrieb John: > I am not sure what you mean as > "devices that have serial numbers?" USB devices can include a unique serial number allowing even devices of the same kind to be distinguished. Thus you would know that exactly the same device has been plugged in.

Re: [linux-usb-devel] Question about usb-serial port registration

2007-03-23 Thread John
> > It seems to me that if we cannot guarantee that > > the devices are identical, we must make sure they > > have different numbers. > What about devices that have serial numbers? > Wouldn't it at least > be a good idea to make their file usage persistant? I am not sure what you mean as "devices

Re: [linux-usb-devel] Question about usb-serial port registration

2007-03-23 Thread Till Harbaum / Lists
Hi, Am Freitag, 23. März 2007 20:36 schrieb John: > It seems to me that if we cannot guarantee that > the devices are identical, we must make sure they > have different numbers. What about devices that have serial numbers? Wouldn't it at least be a good idea to make their file usage persistant? T

[linux-usb-devel] Question about usb-serial port registration

2007-03-23 Thread John
Hi, Since last December me and Oliver are trying to fix a number of problems in usb-serial.c. Most of them happen when devices are plugged and unplugged and files are opened and closed in various orders. usb-serial.c registers new tty ports by calling device_register from usb_serial_probe routine,