From f44c21ff6d2dc76957ddbf26fdf442ee5a9cf3c0 Mon Sep 17 00:00:00 2001 From: Alexandru M Stan Date: Tue, 9 Jun 2015 13:04:48 +0200 Subject: [PATCH] mfd: cros_ec: spi: Add a DT property to delay asserting the CS Some ECs need a little time for waking up before they can accept SPI data at a high speed. Add a "google,cros-ec-spi-pre-delay" property to the DT binding to configure this. 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 beginning of a transaction. Signed-off-by: Alexandru M Stan Reviewed-by: Doug Anderson Signed-off-by: Chris Zhong Signed-off-by: Javier Martinez Canillas Tested-by: Heiko Stuebner Acked-by: Lee Jones Acked-by: Olof Johansson Signed-off-by: Lee Jones --- Documentation/devicetree/bindings/mfd/cros-ec.txt | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/Documentation/devicetree/bindings/mfd/cros-ec.txt b/Documentation/devicetree/bindings/mfd/cros-ec.txt index 8009c3d..1777916 100644 --- a/Documentation/devicetree/bindings/mfd/cros-ec.txt +++ b/Documentation/devicetree/bindings/mfd/cros-ec.txt @@ -18,6 +18,10 @@ Required properties (SPI): - reg: SPI chip select Optional properties (SPI): +- google,cros-ec-spi-pre-delay: Some implementations of the EC need a little + time to wake up from sleep before they can receive SPI transfers at a high + clock rate. This property specifies the delay, in usecs, between the + assertion of the CS to the start of the first clock pulse. - 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 -- 2.7.4