linux-kernel - Re: [PATCH v7 7/8] mfd: cros_ec: spi: Add a DT property to delay asserting the CS

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Date:	Mon, 15 Jun 2015 13:25:05 +0100
From:	Lee Jones <lee.jones@...aro.org>
To:	Javier Martinez Canillas <javier.martinez@...labora.co.uk>
Cc:	Samuel Ortiz <sameo@...ux.intel.com>,
	Olof Johansson <olof@...om.net>,
	Doug Anderson <dianders@...omium.org>,
	Bill Richardson <wfrichar@...omium.org>,
	Simon Glass <sjg@...gle.com>,
	Gwendal Grignou <gwendal@...gle.com>,
	Stephen Barber <smbarber@...omium.org>,
	Filipe Brandenburger <filbranden@...gle.com>,
	Todd Broch <tbroch@...omium.org>,
	Alexandru M Stan <amstan@...omium.org>,
	Heiko Stuebner <heiko@...ech.de>,
	linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org,
	devicetree@...r.kernel.org, Chris Zhong <zyw@...k-chips.com>
Subject: Re: [PATCH v7 7/8] mfd: cros_ec: spi: Add a DT property to delay
 asserting the CS

On Tue, 09 Jun 2015, Javier Martinez Canillas wrote:

> From: Alexandru M Stan <amstan@...omium.org>
> 
> 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 <amstan@...omium.org>
> Reviewed-by: Doug Anderson <dianders@...omium.org>
> Signed-off-by: Chris Zhong <zyw@...k-chips.com>
> Signed-off-by: Javier Martinez Canillas <javier.martinez@...labora.co.uk>
> Tested-by: Heiko Stuebner <heiko@...ech.de>
> Acked-by: Lee Jones <lee.jones@...aro.org>
> Acked-by: Olof Johansson <olof@...om.net>

Applied, thanks.

> ---
> 
> Changes since v6:
>  - Add Olof Johansson Acked-by tag
> 
> Changes since v5: None.
> 
> Changes since v4: None.
> 
> Changes since v3:
>  - Split DT binding and driver change as suggested by Lee Jones.
>  - Add tested-by tag from Heiko Stuebner
>  - Add acked-by tag from Lee Jones.
> 
> Changes since v2: None
> 
> Changes since v1: None, new patch
> ---
>  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 8009c3d87f33..1777916e9e28 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

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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