Em 25-11-2011 13:58, Manu Abraham escreveu: > On Fri, Nov 25, 2011 at 8:52 PM, Hans Verkuil <hverkuil@xxxxxxxxx> wrote: >> On Friday, November 25, 2011 14:48:02 Mauro Carvalho Chehab wrote: >>> Em 25-11-2011 10:00, Andreas Oberritter escreveu: >>>> On 24.11.2011 19:47, Mauro Carvalho Chehab wrote: >>>>> Em 24-11-2011 16:13, Manu Abraham escreveu: >>>>>> On Thu, Nov 24, 2011 at 11:38 PM, Mauro Carvalho Chehab >>>>>> <mchehab@xxxxxxxxxx> wrote: >>>>>>> Em 24-11-2011 16:01, Manu Abraham escreveu: >>>>>>>> On Thu, Nov 24, 2011 at 11:14 PM, Hans Verkuil <hverkuil@xxxxxxxxx> wrote: >>>>>>>>> On Thursday, November 24, 2011 18:08:05 Andreas Oberritter wrote: >>>>>>>>>> Don't break existing Userspace APIs for no reason! It's OK to add the >>>>>>>>>> new API, but - pretty please - don't just blindly remove audio.h and >>>>>>>>>> video.h. They are in use since many years by av7110, out-of-tree drivers >>>>>>>>>> *and more importantly* by applications. Yes, I know, you'd like to see >>>>>>>>>> those out-of-tree drivers merged, but it isn't possible for many >>>>>>>>>> reasons. And even if they were merged, you'd say "Port them and your >>>>>>>>>> apps to V4L". No! That's not an option. >>>>>>>>> >>>>>>>>> I'm not breaking anything. All apps will still work. >>>>>>>>> >>>>>>>>> One option (and it depends on whether people like it or not) is to have >>>>>>>>> audio.h, video.h and osd.h just include av7110.h and add a #warning >>>>>>>>> that these headers need to be replaced by the new av7110.h. >>>>>>>> >>>>>>>> >>>>>>>> That won't work with other non av7110 hardware. >>>>>>> >>>>>>> There isn't any non-av7110 driver using it at the Kernel. Anyway, we can put >>>>>>> a warning at the existing headers as-is, for now, putting them to be removed >>>>>>> for a new kernel version, like 3.4. >>>>>> >>>>>> >>>>>> No, that's not an option. The to-be merged saa716x driver depends on it. >>>>> >>>>> If the driver is not merged yet, it can be changed. >>>>> >>>>>> A DVB alone device need not depend V4L2 for it's operation. >>>>> >>>>> Why not? DVB drivers with IR should implement the input/event/IR API. DVB drivers with net >>>>> should implement the Linux Network API. >>>> >>>> DVB doesn't specify IR. There's no such thing like a DVB IR device. >>>> >>>> IP over DVB is implemented transparently. No driver needs to do anything >>>> but register its device's MAC address, therefore no driver implements >>>> the Linux Network API. >>>> >>>>> There is nothing wrong on using the ALSA API for audio and the V4L2 API for video, >>>>> as both API fits the needs for decoding audio and video streams, and new features >>>>> could be added there when needed. >>>> >>>> Yes. There's nothing wrong with it and I'm not complaining. I don't care >>>> about the implementation of the API in ivtv either. Just don't remove >>>> the API from dvb-core, period. >>>> >>>>> Duplicated API's that become legacy are removed with time. Just to mention two >>>>> notable cases, this happened with the old audio stack (OSS), with the old Wireless >>>>> stack. >>>> >>>> I can still use iwconfig and linux/wireless.h is still available on my >>>> system. >>> >>> Yes, but both iwconfig and the API changed. >>> >>>> ALSA still provides OSS emulation and the real OSS stack was marked >>>> deprecated but still present for ages. >>> >>> OSS driver submission stopped years ago. I remember it clearly as they denied cx88-oss >>> driver submission (2004 or 2005). The saa7134-oss and bttv-oss drivers were dropped in 2007[1] >>> in favor of the alsa drivers. The only hardware that are still there at OSS are the >>> legacy ones that probably no alsa developer has anymore. >>> >>> [1] http://kerneltrap.org/mailarchive/linux-kernel/2007/11/9/398438/thread >>> >>>> In contrast, you want to remove a >>>> stable API and introduce a new *completely untested* API between 3.3 and >>>> 3.4. >>> >>> Please read the patches again. The API for the devices are still there: >>> any binary compiled for older kernels will still work with av7110 and ivtv. >>> With the patches applied, the only difference is that the header file has >>> renamed, as they were moved to device-specific headers. >>> >>> It should be noticed that, while both av7110 and ivtv uses the same ioctl's, av7110 >>> creates devices over /dev/dvb, while ivtv uses it over /dev/video?. So, in practice, >>> each driver has a different API. >>> >>> There are no plans to remove the API for av7110. >>> >>> As discussed on this thread, it seems that the agreed plans for the ivtv API is to put >>> it into the standard kernel procedure to get rid of legacy API. That means that the API >>> will be there for a few kernel versions. >>> >>> Hans proposal is to remove the ivtv API on 3.8, with seems reasonable. So, the first >>> API removal will happen in about 18 months from now (assuming about 2 months per kernel >>> version). >>> >>>>> Do you have any issues that needs to be addressed by the V4L2 API for it to fit >>>>> on your needs? >>>> >>>> I don't want to be forced to use the V4L2 API for no reason and no gain. >>> >>> As already explained on the other email, there are gains on using it, like the support >>> for other types of encoding, the pipeline setup, sub-device control, shared buffer interface >>> with GPU, proper support for SoC, etc. >>> >>> Also, currently, just one device uses it (av7110). I don't think that the chipset is >>> still manufactured. At least Google didn't help finding anything: >>> http://www.google.com/search?q=av7110&tbm=shop&hl=en >>> >>> On the other hand, there are thousands of devices using V4L2 API. >>> >>> As both API's provide support for decoded video, one API has to be deprecated in favor >>> to the other. We should select for deprecation the one that is more restrictive >>> and that has just one driver using it. >>> >>>> >>>>>> Also, it doesn't >>>>>> make any sense to have device specific headers to be used by an application, >>>>>> when drivers share more than one commonality. >>>>> >>>>> The only in-kernel driver using audio/video/osd is av7110. >>>> >>>> Once again: Manu is going to submit a new driver soon. >>> >>> The API is there for several years (since 2002?), with just one driver supporting it. >>> It shouldn't be hard to convert Manu's work to the V4L2. I can help him on converting >>> his driver to use the V4L2 API if needed. >>> >>>> You're trying to remove an API that you've never used. The people who >>>> use the API want it to stay. >>> >>> As I said, it will stay there. Nobody will remove av7110 or remove the old API from it. >>> >>> The idea is that no new driver should use it, as it is a legacy one-driver-only API. >>> >>> If your complain is about the removal of audio.h, video.h and osd.h, then my proposal is >>> to keep it there, writing a text that they are part of a deprecated API, but keeping >>> the rest of the patches and not accepting anymore any submission using them, removing >>> the ioctl's that aren't used by av7110 from them. >> >> I have no problem with that. Something along those lines was my initial idea anyway, >> but I forgot about it. >> >> I've taken a quick look at Manu's driver: it uses very few ioctls from audio.h and >> video.h and it seems that that driver uses the video device as a classic video output >> device able to handle compressed video (I presume an elementary video stream). > > > How will you handle CI+ ? The CI+ descrambler is tightly married to > the DVB decoder. > So you will move the CA API also to V4L, eventually ? No. The idea is to integrate frontend, demux and ca at the Media Controller, in order to allow complex devices to use it. This should solve the issues with: drivers/staging/media/cxd2099/ allowing to move it out of staging. Regards, Mauro -- 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
