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Ian Abbott 15d5193104 staging: comedi: ni_mio_common: fix AO timer off-by-one regression
As reported by Éric Piel on the Comedi mailing list (see
<https://groups.google.com/forum/#!topic/comedi_list/ueZiR7vTLOU/discussion>),
the analog output asynchronous commands are running too fast with a
period 50 ns shorter than it should be.  This affects all boards with AO
command support that are supported by the "ni_pcimio", "ni_atmio", and
"ni_mio_cs" drivers.

This is a regression bug introduced by commit 080e6795cb ("staging:
comedi: ni_mio_common: Cleans up/clarifies ni_ao_cmd"), specifically,
this line in `ni_ao_cmd_set_update()`:

		/* following line: N-1 per STC */
		ni_stc_writel(dev, trigvar - 1, NISTC_AO_UI_LOADA_REG);

The `trigvar` variable value comes from a call to `ni_ns_to_timer()`
which converts a timer period in nanoseconds to a hardware divisor
value. The function already reduces the divisor by 1 as required by the
hardware, so the above line should not reduce it further by 1.  Fix it
by replacing `trigvar` by `trigvar - 1` in the above line, and remove
the misleading comment.

Reported-by: Éric Piel <piel@delmic.com>
Fixes: 080e6795cb ("staging: comedi: ni_mio_common: Cleans up/clarifies ni_ao_cmd")
Cc: Éric Piel <piel@delmic.com>
Cc: Spencer E. Olson <olsonse@umich.edu>
Cc: <stable@vger.kernel.org> # 4.7+
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-07-16 09:13:53 +02:00
Documentation This series converts a number of top-level documents to the RST format 2017-07-15 12:58:58 -07:00
arch Merge branch 'work.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-07-15 12:00:42 -07:00
block Merge branch 'for-linus' of git://git.kernel.dk/linux-block 2017-07-11 15:36:52 -07:00
certs modsign: add markers to endif-statements in certs/Makefile 2017-07-14 11:01:37 +10:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2017-07-14 22:49:50 -07:00
drivers staging: comedi: ni_mio_common: fix AO timer off-by-one regression 2017-07-16 09:13:53 +02:00
firmware firmware/Makefile: force recompilation if makefile changes 2017-05-08 17:15:10 -07:00
fs Add wait_for_random_bytes() and get_random_*_wait() functions so that 2017-07-15 12:44:02 -07:00
include Add wait_for_random_bytes() and get_random_*_wait() functions so that 2017-07-15 12:44:02 -07:00
init random: do not ignore early device randomness 2017-07-12 16:26:00 -07:00
ipc ipc/util.h: update documentation for ipc_getref() and ipc_putref() 2017-07-12 16:26:02 -07:00
kernel Merge branch 'work.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-07-15 12:00:42 -07:00
lib Add wait_for_random_bytes() and get_random_*_wait() functions so that 2017-07-15 12:44:02 -07:00
mm Merge branch 'work.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-07-15 12:00:42 -07:00
net Add wait_for_random_bytes() and get_random_*_wait() functions so that 2017-07-15 12:44:02 -07:00
samples Merge branch 'akpm' (patches from Andrew) 2017-07-13 12:38:49 -07:00
scripts Kbuild updates for v4.13 (2nd) 2017-07-13 13:37:57 -07:00
security KEYS: DH: validate __spare field 2017-07-14 11:01:38 +10:00
sound sound fixes for 4.13-rc1 2017-07-14 12:44:00 -07:00
tools Merge branch 'akpm' (patches from Andrew) 2017-07-14 21:57:25 -07:00
usr ramfs: clarify help text that compression applies to ramfs as well as legacy ramdisk. 2017-07-06 16:24:30 -07:00
virt Second batch of KVM updates for v4.13 2017-07-15 10:18:16 -07:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Add hch to .get_maintainer.ignore 2015-08-21 14:30:10 -07:00
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore kbuild: Add support to generate LLVM assembly files 2017-04-25 08:13:52 +09:00
.mailmap power supply and reset changes for the v4.12 series (part 2) 2017-05-12 12:02:21 -07:00
COPYING
CREDITS avr32: remove support for AVR32 architecture 2017-05-01 09:27:15 +02:00
Kbuild kbuild: Consolidate header generation from ASM offset information 2017-04-13 05:43:37 +09:00
Kconfig
MAINTAINERS Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus 2017-07-15 10:59:54 -07:00
Makefile Linux v4.13-rc1 2017-07-15 15:22:10 -07:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

README

Linux kernel
============

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.