Patch "staging: comedi: adv_pci1710: fix AI INSN_READ for non-zero channel" has been added to the 3.19-stable tree

This is a note to let you know that I've just added the patch titled

staging: comedi: adv_pci1710: fix AI INSN_READ for non-zero channel

to the 3.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
staging-comedi-adv_pci1710-fix-ai-insn_read-for-non-zero-channel.patch
and it can be found in the queue-3.19 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Ian Abbott <[email protected]>
Date: Fri, 27 Feb 2015 16:04:42 +0000
Subject: staging: comedi: adv_pci1710: fix AI INSN_READ for non-zero channel

From: Ian Abbott <[email protected]>

commit abe46b8932dd9a6dfc3698e3eb121809b7b9ed28 upstream.

Reading of analog input channels by the INSN_READ comedi instruction is broken for all except channel 0. pci171x_ai_insn_read() calls pci171x_ai_read_sample() with the wrong value for the third parameter. It is supposed to be the current index in a channel list (which is always of length 1 in this case, so the index should be 0), but instead it is passing the actual channel number. pci171x_ai_read_sample() checks the channel number encoded in the raw sample value read from the hardware matches the channel number stored in the specified index of the previously set up channel list and returns -ENODATA if it doesn't match. Since the index should always be 0 in this case, the match will fail unless the channel number is also 0. Fix it by passing 0 as the channel index.

Note that when the bug first appeared, it was pci171x_ai_dropout() that was called with the wrong parameter value. pci171x_ai_dropout() got replaced with pci171x_ai_read_sample() in commit 7fd2dae2500d ("staging: comedi: adv_pci1710: introduce pci171x_ai_read_sample()").

---
 drivers/staging/comedi/drivers/adv_pci1710.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

@@ -455,7 +455,6 @@ static int pci171x_insn_read_ai(struct c
 				struct comedi_insn *insn, unsigned int *data)
 {
 	struct pci1710_private *devpriv = dev->private;
-	unsigned int chan = CR_CHAN(insn->chanspec);
 	int ret = 0;
 	int i;
 

@@ -477,7 +476,7 @@ static int pci171x_insn_read_ai(struct c
 			break;
 
 		val = inw(dev->iobase + PCI171x_AD_DATA);
-		ret = pci171x_ai_dropout(dev, s, chan, val);
+		ret = pci171x_ai_dropout(dev, s, 0, val);
 		if (ret)
 			break;
 

Patches currently in stable-queue which might be from [email protected] are

queue-3.19/staging-comedi-adv_pci1710-fix-ai-insn_read-for-non-zero-channel.patch