Re: [PATCH 2/5] pcm990 baseboard: add camera bus width switch setting

From: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
To: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Linux Media Mailing List <linux-media@vger.kernel.org>
Subject: Re: [PATCH 2/5] pcm990 baseboard: add camera bus width switch setting
Date: Thu, 9 Apr 2009 23:44:21 +0200 (CEST)	[thread overview]
Message-ID: <Pine.LNX.4.64.0904092339320.4841@axis700.grange> (raw)
In-Reply-To: <20090312141819.GN425@pengutronix.de>

Hi Sascha,

something, that skipped both of us:

On Thu, 12 Mar 2009, Sascha Hauer wrote:

> Some Phytec cameras have a I2C GPIO expander which allows it to
> switch between different sensor bus widths. This was previously
> handled in the camera driver. Since handling of this switch
> varies on several boards the cameras are used on, the board
> support seems a better place to handle the switch
> 
> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
> ---
>  arch/arm/mach-pxa/pcm990-baseboard.c |   53 ++++++++++++++++++++++++++++------
>  1 files changed, 44 insertions(+), 9 deletions(-)
> 
> diff --git a/arch/arm/mach-pxa/pcm990-baseboard.c b/arch/arm/mach-pxa/pcm990-baseboard.c
> index 34841c7..fd8f786 100644
> --- a/arch/arm/mach-pxa/pcm990-baseboard.c
> +++ b/arch/arm/mach-pxa/pcm990-baseboard.c
> @@ -381,14 +381,49 @@ static struct pca953x_platform_data pca9536_data = {
>  	.gpio_base	= NR_BUILTIN_GPIO + 1,
>  };
>  
> -static struct soc_camera_link iclink[] = {
> -	{
> -		.bus_id	= 0, /* Must match with the camera ID above */
> -		.gpio	= NR_BUILTIN_GPIO + 1,
> -	}, {
> -		.bus_id	= 0, /* Must match with the camera ID above */
> -		.gpio	= -ENXIO,
> +static int gpio_bus_switch;
> +
> +static int pcm990_camera_set_bus_param(struct soc_camera_link *link,
> +		unsigned long flags)
> +{
> +	if (gpio_bus_switch <= 0) {
> +		if (flags == SOCAM_DATAWIDTH_10)
> +			return 0;
> +		else
> +			return -EINVAL;
> +	}
> +
> +	if (flags & SOCAM_DATAWIDTH_8)
> +		gpio_set_value(gpio_bus_switch, 1);
> +	else
> +		gpio_set_value(gpio_bus_switch, 0);
> +
> +	return 0;
> +}
> +
> +static unsigned long pcm990_camera_query_bus_param(struct soc_camera_link *link)
> +{
> +	int ret;
> +
> +	if (!gpio_bus_switch) {
> +		ret = gpio_request(NR_BUILTIN_GPIO + 1, "camera");

There's no gpio_free() now... So, for example, you cannot unload the 
extender driver any more, unloading i2c adapter driver (i2c-pxa) produces 
ugly stuff like

pca953x 0-0041: gpiochip_remove() failed, -16

So, we either have to request and free the GPIO in each query / set, or we 
need an explicit .free_bus() call in soc_camera_link. None of the two 
really pleases me, but maybe the latter is slightly less ugly, what do you 
think?

Thanks
Guennadi

> +		if (!ret) {
> +			gpio_bus_switch = NR_BUILTIN_GPIO + 1;
> +			gpio_direction_output(gpio_bus_switch, 0);
> +		} else
> +			gpio_bus_switch = -EINVAL;
>  	}
> +
> +	if (gpio_bus_switch > 0)
> +		return SOCAM_DATAWIDTH_8 | SOCAM_DATAWIDTH_10;
> +	else
> +		return SOCAM_DATAWIDTH_10;
> +}
> +
> +static struct soc_camera_link iclink = {
> +	.bus_id	= 0, /* Must match with the camera ID above */
> +	.query_bus_param = pcm990_camera_query_bus_param,
> +	.set_bus_param = pcm990_camera_set_bus_param,
>  };
>  
>  /* Board I2C devices. */
> @@ -399,10 +434,10 @@ static struct i2c_board_info __initdata pcm990_i2c_devices[] = {
>  		.platform_data = &pca9536_data,
>  	}, {
>  		I2C_BOARD_INFO("mt9v022", 0x48),
> -		.platform_data = &iclink[0], /* With extender */
> +		.platform_data = &iclink, /* With extender */
>  	}, {
>  		I2C_BOARD_INFO("mt9m001", 0x5d),
> -		.platform_data = &iclink[0], /* With extender */
> +		.platform_data = &iclink, /* With extender */
>  	},
>  };
>  #endif /* CONFIG_VIDEO_PXA27x ||CONFIG_VIDEO_PXA27x_MODULE */
> -- 
> 1.5.6.5
> 
> -- 
> Pengutronix e.K.                           |                             |
> Industrial Linux Solutions                 | http://www.pengutronix.de/  |
> Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
> Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |
> 

---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer