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authorPeter Rosin <peda@axentia.se>2017-11-27 17:31:00 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-12-05 11:24:34 +0100
commiteafbee43b7ec603c002e34597ab5f8fc170d7ab4 (patch)
tree738ada8ac5766c53daa3c9f728d6bc7997b0de3d /Documentation
parent8588eb0ce6a639be06110d7bbc8f59d8468ed9b7 (diff)
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hwmon: (jc42) optionally try to disable the SMBUS timeout
commit 68615eb01f82256c19e41967bfb3eef902f77033 upstream. With a nxp,se97 chip on an atmel sama5d31 board, the I2C adapter driver is not always capable of avoiding the 25-35 ms timeout as specified by the SMBUS protocol. This may cause silent corruption of the last bit of any transfer, e.g. a one is read instead of a zero if the sensor chip times out. This also affects the eeprom half of the nxp-se97 chip, where this silent corruption was originally noticed. Other I2C adapters probably suffer similar issues, e.g. bit-banging comes to mind as risky... The SMBUS register in the nxp chip is not a standard Jedec register, but it is not special to the nxp chips either, at least the atmel chips have the same mechanism. Therefore, do not special case this on the manufacturer, it is opt-in via the device property anyway. Signed-off-by: Peter Rosin <peda@axentia.se> Acked-by: Rob Herring <robh@kernel.org> Signed-off-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/devicetree/bindings/hwmon/jc42.txt4
1 files changed, 4 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/hwmon/jc42.txt b/Documentation/devicetree/bindings/hwmon/jc42.txt
index 07a250498fbb..f569db58f64a 100644
--- a/Documentation/devicetree/bindings/hwmon/jc42.txt
+++ b/Documentation/devicetree/bindings/hwmon/jc42.txt
@@ -34,6 +34,10 @@ Required properties:
- reg: I2C address
+Optional properties:
+- smbus-timeout-disable: When set, the smbus timeout function will be disabled.
+ This is not supported on all chips.
+
Example:
temp-sensor@1a {