[ 3.5.y.z extended stable ] Patch "staging: comedi: ni_labpc: set up command4 register *after*" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    staging: comedi: ni_labpc: set up command4 register *after*

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 5746ad639b6230d3c5538cf0cc44003003651a63 Mon Sep 17 00:00:00 2001
From: Ian Abbott <abbotti at mev.co.uk>
Date: Wed, 27 Feb 2013 12:52:46 +0000
Subject: [PATCH] staging: comedi: ni_labpc: set up command4 register *after*
 command3

Commit 22056e2b46246d97ff0f7c6e21a77b8daa07f02c upstream.

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: Ian Abbott <abbotti at mev.co.uk>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/staging/comedi/drivers/ni_labpc.c | 31 ++++++++++++++++---------------
 1 file changed, 16 insertions(+), 15 deletions(-)

diff --git a/drivers/staging/comedi/drivers/ni_labpc.c b/drivers/staging/comedi/drivers/ni_labpc.c
index 5334977..5b2b966 100644
--- a/drivers/staging/comedi/drivers/ni_labpc.c
+++ b/drivers/staging/comedi/drivers/ni_labpc.c
@@ -1275,21 +1275,6 @@ static int labpc_ai_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
 		devpriv->write_byte(devpriv->command1_bits,
 				    dev->iobase + COMMAND1_REG);
 	}
-	/*  setup any external triggering/pacing (command4 register) */
-	devpriv->command4_bits = 0;
-	if (cmd->convert_src != TRIG_EXT)
-		devpriv->command4_bits |= EXT_CONVERT_DISABLE_BIT;
-	/* XXX should discard first scan when using interval scanning
-	 * since manual says it is not synced with scan clock */
-	if (labpc_use_continuous_mode(cmd) == 0) {
-		devpriv->command4_bits |= INTERVAL_SCAN_EN_BIT;
-		if (cmd->scan_begin_src == TRIG_EXT)
-			devpriv->command4_bits |= EXT_SCAN_EN_BIT;
-	}
-	/*  single-ended/differential */
-	if (aref == AREF_DIFF)
-		devpriv->command4_bits |= ADC_DIFF_BIT;
-	devpriv->write_byte(devpriv->command4_bits, dev->iobase + COMMAND4_REG);

 	devpriv->write_byte(cmd->chanlist_len,
 			    dev->iobase + INTERVAL_COUNT_REG);
@@ -1369,6 +1354,22 @@ static int labpc_ai_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
 		devpriv->command3_bits &= ~ADC_FNE_INTR_EN_BIT;
 	devpriv->write_byte(devpriv->command3_bits, dev->iobase + COMMAND3_REG);

+	/*  setup any external triggering/pacing (command4 register) */
+	devpriv->command4_bits = 0;
+	if (cmd->convert_src != TRIG_EXT)
+		devpriv->command4_bits |= EXT_CONVERT_DISABLE_BIT;
+	/* XXX should discard first scan when using interval scanning
+	 * since manual says it is not synced with scan clock */
+	if (labpc_use_continuous_mode(cmd) == 0) {
+		devpriv->command4_bits |= INTERVAL_SCAN_EN_BIT;
+		if (cmd->scan_begin_src == TRIG_EXT)
+			devpriv->command4_bits |= EXT_SCAN_EN_BIT;
+	}
+	/*  single-ended/differential */
+	if (aref == AREF_DIFF)
+		devpriv->command4_bits |= ADC_DIFF_BIT;
+	devpriv->write_byte(devpriv->command4_bits, dev->iobase + COMMAND4_REG);
+
 	/*  startup acquisition */

 	/*  command2 reg */
--
1.8.1.2