On Tue, Sep 26, 2017 at 03:32:23PM +0300, Dmitry Osipenko wrote: > On 26.09.2017 09:54, Greg Kroah-Hartman wrote: > > On Tue, Sep 26, 2017 at 01:15:41AM +0300, Dmitry Osipenko wrote: > >> This driver provides accelerated video decoding to NVIDIA Tegra20 SoC's, > >> it is a result of reverse-engineering efforts. Driver has been tested on > >> Toshiba AC100 and Acer A500, it should work on any Tegra20 device. > >> > >> In userspace this driver is utilized by libvdpau-tegra [0] that implements > >> VDPAU interface, so any video player that supports VDPAU can provide > >> accelerated video decoding on Tegra20 on Linux. > > > > Why not use the v4l2 api instead? Doesn't that provide the same needed > > user/kernel api here instead of creating yet-another-custom ioctl? > > > > 1) The HW doesn't generalize for the common API. Like for example, it isn't > capable of unpacking bitstream encoded with CABAC (Context-adaptive binary > arithmetic coding), so unpacking should be done in software and then VDE HW > isn't capable of decoding such a stream in a fully-automated manner, software > would have to feed engine with a chunks of macroblocks untill the whole frame is > decoded. That lameness is partially hidden in the BLOB's firmware, that firmware > actually is just a driver BTW. > > 2) We want to have decoding integrated with the presentation of the decoded > video frame. So having v4l interface for decoding would be just an extra > unnecessary shim, increasing CPU / memory resources usage and complexity of the > code. > > 3) The decoding and presentation are already implemented using VDPAU API and > proven to work decently in that way. This sounds like something you should be talking over with the media driver developers, why are they not even cc:ed on this submission? I need their ack on this new api before I can take this. thanks, greg k-h -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
