staging: comedi: ni_labpc: set up command4 register *after* command3
Tuomas <tvainikk _at_ gmail _dot_ com> reported problems getting meaningful output from a Lab-PC+ in differential mode for AI cmds, but AI insn reads gave correct readings. He tracked it down to two problems, one of which is addressed by this patch. It seems that writing to the command3 register after writing to the command4 register in `labpc_ai_cmd()` messes up the differential reference bit setting in the command4 register. Set up the command4 register after the command3 register (as in `labpc_ai_rinsn()`) to avoid the problem. Thanks to Tuomas for suggesting the fix. Signed-off-by: NIan Abbott <abbotti@mev.co.uk> Cc: <stable@vger.kernel.org> # 3.7.x, 3.8.x Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
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