The extra rom[0] check is flagging valid temperatures as invalid when
there is already a CRC data transmission check.
w1_therm_read_bin()
if (rom[8] == crc && rom[0])
verdict = 1;
Requiring rom[0] to be non-zero will flag as invalid temperature
conversions when the low byte is zero, specifically the temperatures 0C,
16C, 32C, 48C, -16C, -32C, and -48C.
The CRC check is produced on the device for the previous 8 bytes and is
required to ensure the data integrity in transmission. I don't see why the
extra check for rom[0] being non-zero is in there. Evgeniy Polyakov didn't
know either. Just for a check I unplugged the sensor, executed a
temperature conversion, and read the results. The read was all ff's, which
also failed the CRC, so it doesn't need to protect against a disconnected
sensor.
I have more extensive patches in the work, but these two trivial ones will
do for today. I would like to hear from people who use the ds2490 USB to
one wire dongle. 1 if you would be willing to test the patches as I
currently only have the one sensor on a short parisite powered wire, 2 if
there is any cheap sources for the ds2490.
Signed-off-by: David Fries <david@fries.net>
Acked-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Correct the decoding of negative C temperatures. The code did a binary OR
of two bytes to make a 16 bit value, but assignd it to an integer. This
caused the value to not be sign extended and to loose that it was a
negative number in the assignment.
Before the patch (in my freezer),
w1_slave
ed fe 4b 46 7f ff 03 10 e4 : crc=e4 YES
ed fe 4b 46 7f ff 03 10 e4 t=4078
With the patch,
e3 fe 4b 46 7f ff 0d 10 81 : crc=81 YES
e3 fe 4b 46 7f ff 0d 10 81 t=-17
Signed-off-by: David Fries <david@fries.net>
Acked-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Well, first of all, I don't want to change so many files either.
What I do:
Adding a new parameter "struct bin_attribute *" in the
.read/.write methods for the sysfs binary attributes.
In fact, only the four lines change in fs/sysfs/bin.c and
include/linux/sysfs.h do the real work.
But I have to update all the files that use binary attributes
to make them compatible with the new .read and .write methods.
I'm not sure if I missed any. :(
Why I do this:
For a sysfs attribute, we can get a pointer pointing to the
struct attribute in the .show/.store method,
while we can't do this for the binary attributes.
I don't know why this is different, but this does make it not
so handy to use the binary attributes as the regular ones.
So I think this patch is reasonable. :)
Who benefits from it:
The patch that exposes ACPI tables in sysfs
requires such an improvement.
All the table binary attributes share the same .read method.
Parameter "struct bin_attribute *" is used to get
the table signature and instance number which are used to
distinguish different ACPI table binary attributes.
Without this parameter, we need to offer different .read methods
for different ACPI table binary attributes.
This is impossible as there are various ACPI tables on different
platforms, and we don't know what they are until they are loaded.
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
sysfs is now completely out of driver/module lifetime game. After
deletion, a sysfs node doesn't access anything outside sysfs proper,
so there's no reason to hold onto the attribute owners. Note that
often the wrong modules were accounted for as owners leading to
accessing removed modules.
This patch kills now unnecessary attribute->owner. Note that with
this change, userland holding a sysfs node does not prevent the
backing module from being unloaded.
For more info regarding lifetime rule cleanup, please read the
following message.
http://article.gmane.org/gmane.linux.kernel/510293
(tweaked by Greg to not delete the field just yet, to make it easier to
merge things properly.)
Signed-off-by: Tejun Heo <htejun@gmail.com>
Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
A patch to use ARRAY_SIZE macro already defined in kernel.h
Signed-off-by: Ahmed S. Darwish <darwish.07@gmail.com>
Acked-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Use mutexes instead of semaphores.
Patch tested on x86_64 and i386 with test bus master driver.
Signed-off-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
There are three types of messages between w1 core and userspace:
1. Events. They are generated each time new master or slave device found
either due to automatic or requested search.
2. Userspace commands. Includes read/write and search/alarm search comamnds.
3. Replies to userspace commands.
From: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
David Fries
Zhang Rui
Tejun Heo
Evgeniy Polyakov
Ahmed S. Darwish
Al Viro