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authorSeymour, Shane M <shane.seymour@hpe.com>2015-10-12 04:31:17 +0000
committerJames Bottomley <JBottomley@Odin.com>2015-11-09 17:17:27 -0800
commitd9b43a10f0d04564c6e05de3728c3cbba64c644d (patch)
tree5661a5a688a92e9260af7e7d5cea0a04acca5cf3 /Documentation/ABI/testing/sysfs-driver-st
parentc59ab4e5afade13fdb65efc99c07fb8455aecba5 (diff)
st: allow debug output to be enabled or disabled via sysfs
Change st driver to allow enabling or disabling debug output via sysfs file /sys/bus/scsi/drivers/st/debug_flag. Previously the only way to enable debug output was: 1. loading the driver with the module parameter debug_flag=1 2. an ioctl call (this method was also the only way to dynamically disable debug output). To use the ioctl you need a second tape drive (if you are actively testing the first tape drive) since a second process cannot open the first tape drive if it is in use. The this change is only functional if the value of the macro DEBUG in st.c is a non-zero value (which it is by default). Signed-off-by: Shane Seymour <shane.seymour@hpe.com> Reviewed-by: Laurence Oberman <oberman.l@gmail.com> Acked-by: Kai Mäkisara <kai.makisara@kolumbus.fi> Signed-off-by: James Bottomley <JBottomley@Odin.com>
Diffstat (limited to 'Documentation/ABI/testing/sysfs-driver-st')
-rw-r--r--Documentation/ABI/testing/sysfs-driver-st12
1 files changed, 12 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-driver-st b/Documentation/ABI/testing/sysfs-driver-st
new file mode 100644
index 000000000000..ba5d77008a85
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-driver-st
@@ -0,0 +1,12 @@
+What: /sys/bus/scsi/drivers/st/debug_flag
+Date: October 2015
+Kernel Version: ?.?
+Contact: shane.seymour@hpe.com
+Description:
+ This file allows you to turn debug output from the st driver
+ off if you write a '0' to the file or on if you write a '1'.
+ Note that debug output requires that the module be compiled
+ with the #define DEBUG set to a non-zero value (this is the
+ default). If DEBUG is set to 0 then this file will not
+ appear in sysfs as its presence is conditional upon debug
+ output support being compiled into the module.

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