linux-kernel - Re: [PATCH 04/05] input: RMI4 F01 device control

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Date:	Thu, 31 Jan 2013 00:08:59 -0800
From:	Dmitry Torokhov <dmitry.torokhov@...il.com>
To:	Christopher Heiny <cheiny@...aptics.com>
Cc:	Jean Delvare <khali@...ux-fr.org>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	Linux Input <linux-input@...r.kernel.org>,
	Allie Xiong <axiong@...aptics.com>,
	Vivian Ly <vly@...aptics.com>,
	Daniel Rosenberg <daniel.rosenberg@...aptics.com>,
	Alexandra Chin <alexandra.chin@...synaptics.com>,
	Joerie de Gram <j.de.gram@...il.com>,
	Wolfram Sang <w.sang@...gutronix.de>,
	Mathieu Poirier <mathieu.poirier@...aro.org>,
	Linus Walleij <linus.walleij@...ricsson.com>
Subject: Re: [PATCH 04/05] input: RMI4 F01 device control

Hi Chris,

On Fri, Jan 18, 2013 at 05:12:44PM -0800, Christopher Heiny wrote:
> In addition to the changes described in 0/0 of this patchset, this patch
> includes device serialization updated to conform to the latest RMI4
> specification.

I was looking at the various aspects of the RMI4 patchset, trying to
fix the issues that I see, but there is one big issue that I simply do
not have time to tackle - the driver is completely broken on big endian
architectures due to reliance on bitfileds when exchanging the data with
the device.

Consider the following structures:

>  struct f01_device_status {
> -	u8 status_code:4;
> +	enum rmi_device_status status_code:4;
>  	u8 reserved:2;
>  	u8 flash_prog:1;
>  	u8 unconfigured:1;
> @@ -159,4 +136,113 @@ struct f01_device_control_0 {
>  	u8 configured:1;
>  } __attribute__((__packed__));
>  
> +/**
> + * @reset - set this bit to force a firmware reset of the sensor.
> + */
> +struct f01_device_commands {
> +	u8 reset:1;
> +	u8 reserved:7;
> +};
> +

To make this work on BE boxes you either need to add #ifdefs to the
structures reversing the order of fields or use bit shifts and masks to
get/set specific bits in bytes.

I tried converting F01 code (you can see the [likely broken as I can't
test] result in my tree), but I really do not have time for F11.

Thanks.

-- 
Dmitry
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