[PATCH RFC] arm: omap3evm: Add support for an MT9M032 based camera board.

Thu Jan 20 17:23:07 EST 2011

Hi Laurent,

On Wed, Jan 19, 2011 at 12:38:09AM +0100, Laurent Pinchart wrote:
> Hi Martin,
> 
> Thanks for the patch.
> 
> On Tuesday 18 January 2011 23:32:16 Martin Hostettler wrote:
> > Adds board support for an MT9M032 based camera to omap3evm.
> > 
> > Sigend-off-by: Martin Hostettler <martin at neutronstar.dyndns.org>
> > ---
> >  arch/arm/mach-omap2/Makefile                |    1 +
> >  arch/arm/mach-omap2/board-omap3evm-camera.c |  177 ++++++++++++++++++++++++
> >  2 files changed, 178 insertions(+), 0 deletions(-)
> >  create mode 100644 arch/arm/mach-omap2/board-omap3evm-camera.c
> 
> Is there a special reason to add camera support to a separate file ?

No it's just that the other code i looked at did it in the same way. I don't
really know what's the best way to handle this board code...

> 
> Of course not all OMAP3 EVM systems will use an MT9M032 sensor, so some kind 
> of modularity (and if possible runtime configuration) will be needed.

My 0th version did have a Kconfig option, but i got advise (off-list) that i
should be doing it unconditionally and leave the design for compile or runtime
selection to the developer who adds code for another option.

> 
> [snip]
> 
> > diff --git a/arch/arm/mach-omap2/board-omap3evm-camera.c
> > b/arch/arm/mach-omap2/board-omap3evm-camera.c new file mode 100644
> > index 0000000..ea82a49
> > --- /dev/null
> > +++ b/arch/arm/mach-omap2/board-omap3evm-camera.c
> > @@ -0,0 +1,177 @@
> 
> [snip]
> 
> 
> > +/*
> > + * Copyright (C) 2010-2011 Lund Engineering
> > + * Contact: Gil Lund <gwlund at lundeng.com>
> > + * Author: Martin Hostettler <martin at neutronstar.dyndns.org>
> > + *
> > + * This program is free software; you can redistribute it and/or
> > + * modify it under the terms of the GNU General Public License
> > + * version 2 as published by the Free Software Foundation.
> > + *
> > + * This program is distributed in the hope that it will be useful, but
> > + * WITHOUT ANY WARRANTY; without even the implied warranty of
> > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> > + * General Public License for more details.
> > + *
> > + * You should have received a copy of the GNU General Public License
> > + * along with this program; if not, write to the Free Software
> > + * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
> > + * 02110-1301 USA
> > + */
> > +
> > +#include <linux/i2c.h>
> > +#include <linux/init.h>
> > +#include <linux/platform_device.h>
> > +
> > +#include <asm/gpio.h>
> > +#include <plat/mux.h>
> > +#include "mux.h"
> > +
> > +#include "../../../drivers/media/video/isp/isp.h"
> > +#include "../../../drivers/media/video/mt9m032.h"
> 
> mt9m032.h should be moved to include/media (the same is true for isp.h as 
> well, I'll probably split it and move the part required by board files to 
> include/media/omap3isp.h).

Ok, sounds sensible.

> 
> > +#include "devices.h"
> > +
> > +#define EVM_TWL_GPIO_BASE OMAP_MAX_GPIO_LINES
> > +#define GPIO98_VID_DEC_RES	98
> > +#define nCAM_VD_SEL		157
> > +
> > +#define MT9M032_I2C_BUS_NUM	2
> > +
> > +
> > +enum omap3evmdc_mux {
> > +	MUX_TVP5146,
> > +	MUX_CAMERA_SENSOR,
> > +	MUX_EXP_CAMERA_SENSOR,
> > +};
> > +
> > +/**
> > + * omap3evm_set_mux - Sets mux to enable signal routing to
> > + *                           different peripherals present on new EVM
> > board + * @mux_id: enum, mux id to enable
> > + *
> > + * Returns 0 for success or a negative error code
> > + */
> > +static int omap3evm_set_mux(enum omap3evmdc_mux mux_id)
> > +{
> > +	/* Set GPIO6 = 1 */
> > +	gpio_set_value_cansleep(EVM_TWL_GPIO_BASE + 6, 1);
> > +	gpio_set_value_cansleep(EVM_TWL_GPIO_BASE + 2, 0);
> > +
> > +	switch (mux_id) {
> > +	case MUX_TVP5146:
> > +		gpio_set_value_cansleep(EVM_TWL_GPIO_BASE + 2, 0);
> > +		gpio_set_value(nCAM_VD_SEL, 1);
> > +		break;
> > +
> > +	case MUX_CAMERA_SENSOR:
> > +		gpio_set_value_cansleep(EVM_TWL_GPIO_BASE + 2, 0);
> > +		gpio_set_value(nCAM_VD_SEL, 0);
> > +		break;
> > +
> > +	case MUX_EXP_CAMERA_SENSOR:
> > +		gpio_set_value_cansleep(EVM_TWL_GPIO_BASE + 2, 1);
> > +		break;
> > +
> > +	default:
> > +		pr_err("omap3evm-camera: Invalid mux id #%d\n", mux_id);
> > +		return -EINVAL;
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> 
> > +static int __init camera_init(void)
> > +{
> > +	omap_mux_init_gpio(nCAM_VD_SEL, OMAP_PIN_OUTPUT);
> > +	if (gpio_request(nCAM_VD_SEL, "nCAM_VD_SEL") < 0) {
> > +		pr_err("omap3evm-camera: Failed to get GPIO nCAM_VD_SEL(%d)\n",
> > +		       nCAM_VD_SEL);
> > +		goto err;
> 
> You can return -EINVAL directly here. This removes the need for the 'err' 
> label.

I like to have all error handling work the same way. So one return for error
and one return for success. At least if it's as trivial as here.

> 
> > +	}
> > +	if (gpio_direction_output(nCAM_VD_SEL, 1) < 0) {
> > +		pr_err("omap3evm-camera: Failed to set GPIO nCAM_VD_SEL(%d)
> > direction\n", +		       nCAM_VD_SEL);
> > +		goto err_vdsel;
> > +	}
> > +
> > +	if (gpio_request(EVM_TWL_GPIO_BASE + 2, "T2_GPIO2") < 0) {
> > +		pr_err("omap3evm-camera: Failed to get GPIO T2_GPIO2(%d)\n",
> > +		       EVM_TWL_GPIO_BASE + 2);
> > +		goto err_vdsel;
> > +	}
> > +	if (gpio_direction_output(EVM_TWL_GPIO_BASE + 2, 0) < 0) {
> > +		pr_err("omap3evm-camera: Failed to set GPIO T2_GPIO2(%d) direction\n",
> > +		       EVM_TWL_GPIO_BASE + 2);
> > +		goto err_2;
> > +	}
> > +
> > +	if (gpio_request(EVM_TWL_GPIO_BASE + 8, "nCAM_VD_EN") < 0) {
> > +		pr_err("omap3evm-camera: Failed to get GPIO nCAM_VD_EN(%d)\n",
> > +		       EVM_TWL_GPIO_BASE + 8);
> > +		goto err_2;
> > +	}
> > +	if (gpio_direction_output(EVM_TWL_GPIO_BASE + 8, 0) < 0) {
> > +		pr_err("omap3evm-camera: Failed to set GPIO nCAM_VD_EN(%d) direction\n",
> > +		       EVM_TWL_GPIO_BASE + 8);
> > +		goto err_8;
> > +	}
> > +
> > +	omap3evm_set_mux(MUX_CAMERA_SENSOR);
> > +
> > +
> > +	return omap3_init_camera(&isp_platform_data);
> 
> If this call fails, shouldn't you free the GPIOs ?

Yes, indeed.

> 
> > +
> > +err_8:
> > +	gpio_free(EVM_TWL_GPIO_BASE + 8);
> > +err_2:
> > +	gpio_free(EVM_TWL_GPIO_BASE + 2);
> > +err_vdsel:
> > +	gpio_free(nCAM_VD_SEL);
> > +err:
> > +	return -EINVAL;
> > +}
> > +
> > +device_initcall(camera_init);
> 
> If the code is kept in its own file, you should make camera_init non-static 
> (and rename it) and call it from the OMAP3 EVM initialization function 
> instead.

If it's agreed that that's the right way i can do this.

regards,
 - Martin Hostettler