On Thu, 16 Apr 2009, Dongsoo, Nathaniel Kim wrote: > Hello Guennadi, > > > Reviewing your patch, I've got curious about a thing. > I think your soc camera subsystem is covering multiple camera > devices(sensors) in one target board, but if that is true I'm afraid > I'm confused how to handle them properly. > Because according to your patch, video_dev_create() takes camera > device as parameter and it seems to be creating device node for each > camera devices. This patch is a preparatory step for the v4l2-(sub)dev conversion. With it yes (I think) a video device will be created for every registered on the platform level camera, but only the one(s) that probed successfully will actually work, others will return -ENODEV on open(). > It means, if I have one camera host and several camera devices, there > should be several device nodes for camera devices but cannot be used > at the same time. Because typical camera host(camera interface) can > handle only one camera device at a time. But multiple device nodes > mean "we can open and handle them at the same time". > > How about registering camera host device as v4l2 device and make > camera device a input device which could be handled using > VIDIOC_S_INPUT/G_INPUT api? There are also cases, when you have several cameras simultaneously (think for example about stereo vision), even though we don't have any such cases just yet. > Actually, I'm working on S3C64xx camera interface driver with soc > camera subsystem, Looking forward to it!:-) > and I'm facing that issue right now because I've got > dual camera on my target board. Good, I think, there also has been a similar design based on a pxa270 SoC. How are cameras switched in your case? You probably have some additional hardware logic to switch between them, right? So, you need some code to control that. I think, you should even be able to do this automatically in your platform code using power hooks from the struct soc_camera_link. You could fail to power on a camera if another camera is currently active. In fact, I have to add a return code test to the call to icl->power(icl, 1) in soc_camera_open(), I'll do this for the final v4l2-dev version. Would this work for you or do you have another requirements? In which case, can you describe your use-case in more detail - should both cameras be open by applications simultaneously (looks like not), do you need a more explicit switching control, than just "first open switches," which shouldn't be the case, since you can even create a separate task, that does nothing but just keeps the required camera device open. > I hope you to consider this concept, and also want to know your opinion. Thanks Guennadi --- Guennadi Liakhovetski, Ph.D. Freelance Open-Source Software Developer -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
