From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1161443AbcHENnz (ORCPT <rfc822;w@1wt.eu>);
	Fri, 5 Aug 2016 09:43:55 -0400
Received: from foss.arm.com ([217.140.101.70]:56514 "EHLO foss.arm.com"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1161130AbcHENnx (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
	Fri, 5 Aug 2016 09:43:53 -0400
Date: Fri, 5 Aug 2016 14:43:43 +0100
From: Mark Rutland <mark.rutland@arm.com>
To: Fabien Lahoudere <fabien.lahoudere@collabora.co.uk>
Cc: Mark Brown <broonie@kernel.org>, Rob Herring <robh+dt@kernel.org>,
        "open list:SPI SUBSYSTEM" <linux-spi@vger.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
	<devicetree@vger.kernel.org>,
        open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/1] generic spidev devices must be registered
Message-ID: <20160805134342.GD25152@leverpostej>
References: <1470402714-10798-1-git-send-email-fabien.lahoudere@collabora.co.uk>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <1470402714-10798-1-git-send-email-fabien.lahoudere@collabora.co.uk>
User-Agent: Mutt/1.5.21 (2010-09-15)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Fri, Aug 05, 2016 at 03:11:53PM +0200, Fabien Lahoudere wrote:
> Adding spidev in the compatible list, let configure spidev from device tree
> instead of C source code.

I'm not keen on this.

It ties the hardware description to today's use-case, and leaves the DT
without information regarding the particuarl device. The binding is also
written in terms of the userspace interface, which is backwards.

So NAK to this as-is.

Thanks,
Mark.

> 
> Signed-off-by: Fabien Lahoudere <fabien.lahoudere@collabora.co.uk>
> ---
>  Documentation/devicetree/bindings/spi/spidev.txt | 16 ++++++++++++++++
>  drivers/spi/spidev.c                             |  1 +
>  2 files changed, 17 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/spi/spidev.txt
> 
> diff --git a/Documentation/devicetree/bindings/spi/spidev.txt b/Documentation/devicetree/bindings/spi/spidev.txt
> new file mode 100644
> index 0000000..23200f2
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/spi/spidev.txt
> @@ -0,0 +1,16 @@
> +* SPIDEV
> +
> +spidev is a device driver to access to SPI devices using normal userspace I/O calls.
> +To make an SPI device compatible with this drivers add:
> +
> +Required properties:
> +- compatible : should be "spidev".
> +
> +Example:
> +
> +spidev0: spi@0 {
> +	compatible = "spidev";
> +	reg = <0>;
> +	spi-max-frequency = <1000000>;
> +	status = "okay";
> +};
> diff --git a/drivers/spi/spidev.c b/drivers/spi/spidev.c
> index 2e05046..d780491 100644
> --- a/drivers/spi/spidev.c
> +++ b/drivers/spi/spidev.c
> @@ -696,6 +696,7 @@ static struct class *spidev_class;
>  static const struct of_device_id spidev_dt_ids[] = {
>  	{ .compatible = "rohm,dh2228fv" },
>  	{ .compatible = "lineartechnology,ltc2488" },
> +	{ .compatible = "spidev" },
>  	{},
>  };
>  MODULE_DEVICE_TABLE(of, spidev_dt_ids);
> -- 
> 2.7.4
>