staging: comedi: adq12b: fix ctreg (ai channel/range) programming
authorH Hartley Sweeten <hsweeten@visionengravers.com>
Wed, 28 May 2014 23:34:47 +0000 (16:34 -0700)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Wed, 18 Jun 2014 21:34:44 +0000 (14:34 -0700)
commitf93b399b137062b9108b2bd4cbc5f849d983c19f
tree786d8130103b95f1e659bbf7c678b00e2c99a037
parentd9c4261f6a35bf9067ba0fdaf8ed4775ee0c5cea
staging: comedi: adq12b: fix ctreg (ai channel/range) programming

This driver only updates the ctreg (ai channel/range) register if the
desired channel or range has changed since the last analog input read
operation. It does this becuase the hardware requires an udelay to
allow the multiplexor to settle. Unfortunatly the current code never
updates the 'last_channel' and 'last_range' in the private data so
the ctreg gets updated every time.

Fix this and simplify it a bit by just storing the last ctreg value
in the private data.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/staging/comedi/drivers/adq12b.c