[PATCH] devices.txt: improve entry for comedi (char major 98)

[Ian Abbott]

Describe how the comedi minor device numbers are split across comedi
devices and comedi subdevices.

Replace the current, long dead URL with an official URL for the Comedi
project.

Signed-off-by: Ian Abbott <abbotti@xxxxxxxxx>
---
 Documentation/admin-guide/devices.txt | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/Documentation/admin-guide/devices.txt b/Documentation/admin-guide/devices.txt
index e56e00655153..1c5d2281efc9 100644
--- a/Documentation/admin-guide/devices.txt
+++ b/Documentation/admin-guide/devices.txt
@@ -1647,8 +1647,17 @@
 		  0 = /dev/comedi0	First comedi device
 		  1 = /dev/comedi1	Second comedi device
 		    ...
+		 47 = /dev/comedi47	48th comedi device
 
-		See http://stm.lbl.gov/comedi.
+		Minors 48 to 255 are reserved for comedi subdevices with
+		pathnames of the form "/dev/comediX_subdY", where "X" is the
+		minor number of the associated comedi device and "Y" is the
+		subdevice number.  These subdevice minors are assigned
+		dynamically, so there is no fixed mapping from subdevice
+		pathnames to minor numbers.
+
+		See http://www.comedi.org/ for information about the Comedi
+		project.
 
   98 block	User-mode virtual block device
 		  0 = /dev/ubda		First user-mode block device
-- 
2.23.0