|author||Rhyland Klein <firstname.lastname@example.org>||2013-12-09 12:36:09 +0100|
|committer||Lee Jones <email@example.com>||2014-01-21 08:28:06 +0000|
mfd: cros ec: spi: Add delay for raising CS
The EC has specific timing it requires. Add support for an optional delay after raising CS to fix timing issues. This is configurable based on a DT property "google,cros-ec-spi-msg-delay". If this property isn't set, then no delay will be added. However, if set it will cause a delay equal to the value passed to it to be inserted at the end of a transaction. Signed-off-by: Rhyland Klein <firstname.lastname@example.org> Reviewed-by: Bernie Thompson <email@example.com> Reviewed-by: Andrew Bresticker <firstname.lastname@example.org> Acked-by: Mark Rutland <email@example.com> Signed-off-by: Thierry Reding <firstname.lastname@example.org> Signed-off-by: Lee Jones <email@example.com>
Diffstat (limited to 'Documentation')
1 files changed, 9 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/mfd/cros-ec.txt b/Documentation/devicetree/bindings/mfd/cros-ec.txt
index 5f229c5f6da9..8009c3d87f33 100644
@@ -17,6 +17,15 @@ Required properties (SPI):
- compatible: "google,cros-ec-spi"
- reg: SPI chip select
+Optional properties (SPI):
+- google,cros-ec-spi-msg-delay: Some implementations of the EC require some
+ additional processing time in order to accept new transactions. If the delay
+ between transactions is not long enough the EC may not be able to respond
+ properly to subsequent transactions and cause them to hang. This property
+ specifies the delay, in usecs, introduced between transactions to account
+ for the time required by the EC to get back into a state in which new data
+ can be accepted.
Required properties (LPC):
- compatible: "google,cros-ec-lpc"
- reg: List of (IO address, size) pairs defining the interface uses