On Thursday 17 December 2015 12:58:06 Mauro Carvalho Chehab wrote: > > Can you clarify how the 'topology_version' is used here? Is that > > the version of the structure layout that decides how we interpret the > > rest, or is it a number that is runtime dependent? > > No, topology_version is just a mononotonic counter that starts on 0 > and it is incremented every time a graph object is added or removed. > > It is meant to be used to track if the topology changes after a previous > call to this ioctl. > > On existing media controller embedded device hardware, it should > always be zero, but on devices that allow dynamic hardware changes > (some embedded DTV hardware allows that - also on devices with FPGA, > with RISC CPUs or hot-pluggable devices) should use it to know if the > hardware got modified. > > This is also needed on multi-function devices where different drivers > are used for each function. That's the case of au0828, with uses a > media driver for video, and the standard USB Audio Class driver for > audio. As the drivers are independent, the topology_version will > be zero when the first driver is loaded, but it will change during > at probe time on second driver. It will also be increased if one > of the drivers got unbind. Ok, got it. Thanks for the explanation. Arnd -- 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
