80c002ddd2
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> |
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acorn/char | ||
acpi | ||
amba | ||
ata | ||
atm | ||
auxdisplay | ||
base | ||
block | ||
bluetooth | ||
cdrom | ||
char | ||
clocksource | ||
connector | ||
cpufreq | ||
cpuidle | ||
crypto | ||
dca | ||
dio | ||
dma | ||
edac | ||
eisa | ||
firewire | ||
firmware | ||
hid | ||
hwmon | ||
i2c | ||
ide | ||
ieee1394 | ||
infiniband | ||
input | ||
isdn | ||
kvm | ||
leds | ||
lguest | ||
macintosh | ||
mca | ||
md | ||
media | ||
message | ||
mfd | ||
misc | ||
mmc | ||
mtd | ||
net | ||
nubus | ||
of | ||
oprofile | ||
parisc | ||
parport | ||
pci | ||
pcmcia | ||
pnp | ||
power | ||
ps3 | ||
rapidio | ||
rtc | ||
s390 | ||
sbus | ||
scsi | ||
serial | ||
sh | ||
sn | ||
spi | ||
ssb | ||
tc | ||
telephony | ||
uio | ||
usb | ||
video | ||
virtio | ||
w1 | ||
watchdog | ||
xen | ||
zorro | ||
Kconfig | ||
Makefile |