On Mon, 2012-06-18 at 09:29 +0200, Hans Verkuil wrote: > On Mon June 18 2012 06:49:58 David Dillow wrote: > > What does the V4L2 API spec say about tuning frequency being persistent > > when there are no users of a video capture device? Is MythTV wrong to > > have that assumption, or is cx231xx wrong to not restore the frequency > > when a user first opens the device? > > Tuner standards and frequencies must be persistent. So cx231xx is wrong. > Actually, all V4L2 settings must in general be persistent (there are > some per-filehandle settings when dealing with low-level subdev setups or > mem2mem devices). Is there a document somewhere I can reference; I need to go through the cx231xx driver and make sure it is doing the right things and it would be handy to have a checklist. > > Either way, I think MythTV should keep the device open until it is done > > with it, as that would avoid added latency from putting the tuner to > > sleep and waking it back up. But, I think we should address the issue in > > the driver if it is not living up to the guarantees of the API. > > From what I can tell it is a bug in the tda tuner (not restoring the frequency) > and cx231xx (not setting the initial standard and possibly frequency). Ok, I'll break this up and have a go at a proper fix. Thanks for the pointers on the persistence of parameters. Dave -- 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
