On 03/20/2017 03:11 PM, Russell King - ARM Linux wrote: > On Mon, Mar 20, 2017 at 02:57:03PM +0100, Hans Verkuil wrote: >> On 03/20/2017 02:29 PM, Russell King - ARM Linux wrote: >>> It's what I have - remember, not everyone is happy to constantly replace >>> their distro packages with random new stuff. >> >> This is a compliance test, which is continuously developed in tandem with >> new kernel versions. If you are working with an upstream kernel, then you >> should also use the corresponding v4l2-compliance test. What's the point >> of using an old one? >> >> I will not support driver developers that use an old version of the >> compliance test, that's a waste of my time. > > The reason that people may _not_ wish to constantly update v4l-utils > is that it changes the libraries installed on their systems. > > So, the solution to that is not to complain about developers not using > the latest version, but instead to de-couple it from the rest of the > package, and provide it as a separate, stand-alone package that doesn't > come with all the extra baggage. > > Now, there's two possible answers to that: > > 1. it depends on the libv4l2 version. If that's so, then you are > insisting that people constantly move to the latest libv4l2 because > of API changes, and those API changes may upset applications they're > using. So this isn't really on. > > 2. it doesn't depend on libv4l2 version, in which case there's no reason > for it to be packaged with v4l-utils. Run configure with --disable-v4l2-compliance-libv4l. This avoids linking with libv4l and allows you to build it stand-alone. Perhaps I should invert this option since in most cases you don't want to run v4l2-compliance with libv4l (it's off by default unless you pass the -w option to v4l2-compliance). > > The reality is that v4l2-compliance links with libv4l2, so I'm not sure > which it is. What I am sure of is that I don't want to upgrade libv4l2 > on an ad-hoc basis, potentially causing issues with applications. > >>>> To test actual streaming you need to provide the -s option. >>>> >>>> Note: v4l2-compliance has been developed for 'regular' video devices, >>>> not MC devices. It may or may not work with the -s option. >>> >>> Right, and it exists to verify that the establised v4l2 API is correctly >>> implemented. If the v4l2 API is being offered to user applications, >>> then it must be conformant, otherwise it's not offering the v4l2 API. >>> (That's very much a definition statement in itself.) >>> >>> So, are we really going to say MC devices do not offer the v4l2 API to >>> userspace, but something that might work? We've already seen today >>> one user say that they're not going to use mainline because of the >>> crud surrounding MC. >>> >> >> Actually, my understanding was that he was stuck on the old kernel code. > > Err, sorry, I really don't follow. Who is "he"? "one user say that they're not going to use mainline because of the crud surrounding MC." > > _I_ was the one who reported the EXPBUF problem. Your comment makes no > sense. > >> In the case of v4l2-compliance, I never had the time to make it work with >> MC devices. Same for that matter of certain memory to memory devices. >> >> Just like MC devices these too behave differently. They are partially >> supported in v4l2-compliance, but not fully. > > It seems you saying that the API provided by /dev/video* for a MC device > breaks the v4l2-compliance tests? There may be tests in the compliance suite that do not apply for MC devices and for which I never check. The compliance suite was never written with MC devices in mind, and it certainly hasn't been tested much with such devices. It's only very recent that I even got hardware that has MC support... >From what I can tell from the feedback I got it seems to be OKish, but I just can't guarantee that the compliance utility is correct for such devices. In particular I doubt the streaming tests (-s, -f, etc.) will work. The -s test *might* work if the pipeline is configured correctly before running v4l2-compliance. I can't imagine that the -f option would work at all since I would expect pipeline validation errors. I've been gently pushing Helen Koike to finish her virtual MC driver (https://patchwork.kernel.org/patch/9312783/) since having a virtual driver makes writing compliance tests much easier. > _No one_ has mentioned using v4l2-compliance on the subdevs. > >> Complaining about this really won't help. We know it's a problem and unless >> someone (me perhaps?) manages to get paid to work on this it's unlikely to >> change for now. > > Like the above comment, your comment makes no sense. I'm not complaining, > I'm trying to find out the details. Must be me then, it did feel like complaining... > Yes, MC stuff sucks big time right now, the documentation is poor, there's > a lack of understanding on all sides of the issues (which can be seen by > the different opinions that people hold.) The only way to resolve these > differences is via discussion, and if you're going to start thinking that > everyone is complaining, then there's not going to be any forward progress. > Regards, Hans
