Re: [PATCH] devicetree: Add video bus switch
From: Pavel Machek <hidden>
Date: 2017-02-13 09:54:27
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From: Pavel Machek <hidden>
Date: 2017-02-13 09:54:27
Also in:
linux-media, lkml
Hi!
quoted
Take a look at the wikipedia. If you do "one at a time" at 100Hz, you can claim it is time-domain multiplex. But we are plain switching the cameras. It takes second (or so) to setup the pipeline. This is not multiplex.The functionality is still the same, isn't it? Does it change what it is if the frequency might be 100 Hz or 0,01 Hz?
Well. In your living your you can have a switch, which is switch at much less than 0.01Hz. You can also have a dimmer, which is a PWM, which is switch at 100Hz or so. So yes, I'd say switch and mux are different things.
I was a bit annoyed for having to have two drivers for switching the source (one for GPIO, another for syscon / register), where both of the drivers would be essentially the same with the minor exception of having a slightly different means to toggle the mux setting.
Well, most of the video-bus-switch is the video4linux glue. Actual switching is very very small part. So.. where is the other driver? Looks like we have the same problem.
The MUX framework adds an API for controlling the MUX. Thus we'll need only a single driver that uses the MUX framework API for V4L2. As an added bonus, V4L2 would be in line with the rest of the MUX usage in the kernel. The set appears to already contain a GPIO MUX. What's needed would be to use the MUX API instead of direct GPIOs usage.
If there's a driver that already does switching for video4linux devices? Do you have a pointer? Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html