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Hans Verkuil
8ab75e3ecd
Using the V4L2 core lock is a very robust method that is usually very good at doing the right thing. But some drivers, particularly USB drivers, may want to prevent the core from taking the lock for specific ioctls, particularly buffer queuing ioctls. The reason is that certain commands like S_CTRL can take a long time to process over USB and all the time the core has the lock, preventing VIDIOC_DQBUF from proceeding, even though a frame may be ready in the queue. This introduces unwanted latency. Since the buffer queuing commands often have their own internal lock it is often not necessary to take the core lock. Drivers can now say that they don't want the core to take the lock for specific ioctls. As it is a specific opt-out it makes it clear to the reviewer that those ioctls will need more care when reviewing. Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com> Acked-by: Hans de Goede <hdegoede@redhat.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
tlg2300 release notes ==================== This is a v4l2/dvb device driver for the tlg2300 chip. current status ============== video - support mmap and read().(no overlay) audio - The driver will register a ALSA card for the audio input. vbi - Works for almost TV norms. dvb-t - works for DVB-T FM - Works for radio. --------------------------------------------------------------------------- TESTED APPLICATIONS: -VLC1.0.4 test the video and dvb. The GUI is friendly to use. -Mplayer test the video. -Mplayer test the FM. The mplayer should be compiled with --enable-radio and --enable-radio-capture. The command runs as this(The alsa audio registers to card 1): #mplayer radio://103.7/capture/ -radio adevice=hw=1,0:arate=48000 \ -rawaudio rate=48000:channels=2 --------------------------------------------------------------------------- KNOWN PROBLEMS: about preemphasis: You can set the preemphasis for radio by the following command: #v4l2-ctl -d /dev/radio0 --set-ctrl=pre_emphasis_settings=1 "pre_emphasis_settings=1" means that you select the 50us. If you want to select the 75us, please use "pre_emphasis_settings=2"