Markus, Em Ter, 2007-08-14 às 16:31 +0200, Markus Rechberger escreveu: > Following patch adds the possibility to implement tuner drivers in > userspace.
As you asked me about userspace driver, at Linux Conf Europe, let me give you my feedback about it. On Linux, userspace-to-kernelspace APIs are meant to be forever. This means that, once a newer API is created, this should remain supported for all future versions. So, such APIs should be carefully analyzed and accepted by the community, before going to mainstream. I don't see any technical reason why tuner drivers should be moved to userspace. Looking at xc3028 device, the driver is very simple and doesn't require any special treatment that it isn't possible to be done at kernel. There are already some implementations on kernelspace that works fine. On the other hand, a TV driver without a tuner is a broken driver. With parts of the driver being at userspace, this means to add undesired complexity at the drivers architecture, while not bringing any benefit. If you look at V4L history, the first drivers started at userspace, being migrated to kernelspace, where we have the proper scenario for managing those devices. Another aspect that should be analyzed is what is desired by the community: kernelspace tuners or userspace tuners. Keeping support for both at long term doesn't seem reasonable. The Linux community should decide what is the better way. Currently, only you are pushing for userspace tuners, mainly due to non-technical reasons. Almost all the other developers are comfortable with kernelspace tuners. So, creating an userspace interface just to make you happy is not the way we should go. A final aspect is that having an userspace driver for tuner will mean that the kernel driver will depend on an userspace counterpart in order to work. This will allow a vendor with bad intentions to release a partially broken userspace driver, with limited capabilities, and a closed source driver for full support. This model is likely to occur, if you take a look at the past. For example: ATI and Nvidia closed source drivers, several soft modem drivers, some network drivers, ... With all those issues, I'm against to add an userspace interface for tuners. Cheers, Mauro _______________________________________________ linux-dvb mailing list linux-dvb@linuxtv.org http://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb
