On Wed, 4 May 2011, ÀÖÃô wrote:
> Dear Guennadi:
>
> Thanks for you help,now I think I can send emails to
> <linux-media@vger.kernel.org> .there is still one thing I can not
> understand.The
> question is in the end of this email.
>
> > > > (3) There is a host only, so I think if there are two camera
> > > > sensors,when one sensor is working,another sensor will be poweroff and
> > > > can not be actived.The method to switch between them I think is to close
> > > > the sensor which is not in use.
> > > >
> > > > Can you tell me whether the CEU can connect multiple sensors or not,If
> > > > yes,are there some restrictions?
> >
> > It should work, yes. Currently soc-camera handles client devices (e.g.,
> > sensors) in the following way: first during probing it attaches each such
> > client device to the host, performs probing _and_ detaches it immediately.
> > Then at open() the same happens - only the respective sensor is attached
> > to the host, so, the CEU driver only has to deal with one sensor at a
> > time. Just make sure to not try to open both nodes at the same time.
> >
> > > > If it supports multiple sensors ,what should I do?
> >
> > Just that - write two independent sensor drivers and two platform data
> > blocks for them in your board file. Then open and operate each sensor
> > independently. You also might want to provide platform struct
> > soc_camera_link::power() and / or reset() callbacks.
>
>
> You say soc_camera will attach each sensor in the probing,but I think
> each time there is
> only one sensor can register to soc_camera subsystem.
Correct. During probing each client device will be attached to the host,
probed, and detached again.
> look at the following
> code:
>
> struct i2c_board_info ov9640_info1=
> {
> ....
> };
>
> struct soc_camera_link ov9640_link1=
> {
> .board_info=&ov9640_info1,
> ..........
> };
>
> struct platform_device ov9640_device1=
> {
> .name = "soc-camera-pdrv",
> .dev=
> {
> .platform_data = &ov9640_link1,
> }
> };
>
> struct i2c_board_info ov9640_info2=
> {
> ....
> };
>
> struct soc_camera_link ov9640_link2=
> {
> .board_info=&ov9640_info2,
> ..........
> };
>
> struct platform_device ov9640_device2=
> {
> .name = "soc-camera-pdrv", //the name is same to the
> ov_9640_device1.
> .dev=
> {
> .platform_data = &ov9640_link2,
> }
> };
>
> There are two sensors,now I want they all exist in /dev after
> linux system is
> boot.can I do this? if yes I want to use platform_device_register()
> twice.but this action is forbindden,because they have the same
> platform name,so only one sensor can registered successfully.
You should use different IDs. Look at arch/sh/boards/mach-migor/setup.c or
arch/arm/mach-mx3/mach-pcm037.c for examples.
> On the other hand if I use soc_camera subsystem to register a
> video device to let
> system create a node in /dev,like /dev/video0 or /dev/video1.I must
> call soc_camera_device_register() to register a soc_camera_device to
> soc_camera,
> then if there is a camera host is registered to soc_camera,the host
> will call scan_add_host() to probe and attach each sensor,if host can
> handle the sensor,
> device_register() will be called,finally the probe function of
> soc_camera bus------soc_camera_probe() will be called,in this function
> a video device will be register to the system,and a device node will
> be create in /dev if all information of the sensor is ok.
>
> So if you want to register a video device and create a device
> node in /dev using soc_camera,soc_camera_device_register() must be
> called.But now the only way to call soc_camera_device_register() is
> to register a platform device whose name is "soc-pdrv".
> Is my analysis right ?
>
> I do not want to use modle to load the driver,I want the two
> sensors' device node can all exist in /dev directory after the system
> is booted,what should I do.the kernel vesion I used is 2.6.36.Please
> help me.
Would also be good to use the current kernel version for any new
development. In my replies I'm targeting the newest kernel(s), and if you
encounter any problems / questions, specific to an older version, I am
afraid, I won't be able to help you. Also to mainline your work you'll
have to submit patches for the latest kernel.
Thanks
Guennadi
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/
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