This is a note to let you know that I've just added the patch titled
staging: comedi: ni_mio_common: fix E series ni_ai_insn_read() data
to my staging git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git
in the staging-next branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will also be merged in the next major kernel release
during the merge window.
If you have any questions about this process, please let me know.
>From 857a661020a2de3a0304edf33ad656abee100891 Mon Sep 17 00:00:00 2001
From: Ian Abbott <abbotti@xxxxxxxxx>
Date: Mon, 14 Nov 2016 20:16:22 +0000
Subject: staging: comedi: ni_mio_common: fix E series ni_ai_insn_read() data
Commit 0557344e2149 ("staging: comedi: ni_mio_common: fix local var for
32-bit read") changed the type of local variable `d` from `unsigned
short` to `unsigned int` to fix a bug introduced in
commit 9c340ac934db ("staging: comedi: ni_stc.h: add read/write
callbacks to struct ni_private") when reading AI data for NI PCI-6110
and PCI-6111 cards. Unfortunately, other parts of the function rely on
the variable being `unsigned short` when an offset value in local
variable `signbits` is added to `d` before writing the value to the
`data` array:
d += signbits;
data[n] = d;
The `signbits` variable will be non-zero in bipolar mode, and is used to
convert the hardware's 2's complement, 16-bit numbers to Comedi's
straight binary sample format (with 0 representing the most negative
voltage). This breaks because `d` is now 32 bits wide instead of 16
bits wide, so after the addition of `signbits`, `data[n]` ends up being
set to values above 65536 for negative voltages. This affects all
supported "E series" cards except PCI-6143 (and PXI-6143). Fix it by
ANDing the value written to the `data[n]` with the mask 0xffff.
Fixes: 0557344e2149 ("staging: comedi: ni_mio_common: fix local var for 32-bit read")
Signed-off-by: Ian Abbott <abbotti@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
----
Needs backporting to stable kernels 3.18 onwards.
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/staging/comedi/drivers/ni_mio_common.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/drivers/staging/comedi/drivers/ni_mio_common.c b/drivers/staging/comedi/drivers/ni_mio_common.c
index 95435395c746..a974ab772937 100644
--- a/drivers/staging/comedi/drivers/ni_mio_common.c
+++ b/drivers/staging/comedi/drivers/ni_mio_common.c
@@ -1875,7 +1875,7 @@ static int ni_ai_insn_read(struct comedi_device *dev,
return -ETIME;
}
d += signbits;
- data[n] = d;
+ data[n] = d & 0xffff;
}
} else if (devpriv->is_6143) {
for (n = 0; n < insn->n; n++) {
@@ -1924,9 +1924,8 @@ static int ni_ai_insn_read(struct comedi_device *dev,
data[n] = dl;
} else {
d = ni_readw(dev, NI_E_AI_FIFO_DATA_REG);
- /* subtle: needs to be short addition */
d += signbits;
- data[n] = d;
+ data[n] = d & 0xffff;
}
}
}
--
2.10.2
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