Experimental Physics and Industrial Control System
Subject: |
I/O Interrupt Scanning |
From: |
Andrew Johnson <[email protected]> |
Date: |
Tue, 10 Jan 1995 20:49:27 GMT |
Question: Is it legal to call scanIoInit from within a get_ioint_info device
routine?
I am writing a driver which could conceivably have up to 255 different I/O
interrupt event sources (although they all come through one ISR).
At present within the device initialisation routine I check if a record is set
to I/O Interrupt scanning and call scanIoInit if it is. For a record which
started out as I/O Interrupt I can subsequently set the SCAN field to Passive,
I/O Intr or one of the periodics.
However for records which are not set to I/O Interrupt scan at initialisation, I
don't call scanIoInit, so if I later try to change the SCAN field on these
records to I/O Interrupt, get_ioint_info has to return an error and the SCAN
field will not be altered.
For performance reasons I don't want to set up the IOSCANPVT unless the database
application needs it, so I wondered whether can I call scanIoInit from within
the get_ioint_info device routine, then store and return the IOSCANPVT pointer
immediately?
- Andrew
,_}\_. Andrew Johnson, Technology Division
/ \ Royal Greenwich Observatory
~~~~~~~~| ,--/;. )~~~~ Madingley Road, Cambridge, UK
., |/ (/ U Phone: +44 (0)1223 374823
.`., /_\ . . Email: [email protected]
wwWWWww' WWW: http://cast0.ast.cam.ac.uk/~anj/
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