| Message ID | 20200608191333.1784963-1-dwlsalmeida@gmail.com |
|---|---|
| Headers | show |
| Series | media: vidtv: implement a virtual DVB driver | expand |
Hi Mauro, On 6/8/20 1:13 PM, Daniel W. S. Almeida wrote: > From: "Daniel W. S. Almeida" <dwlsalmeida@gmail.com> > > This series is work in progress. It represents the current work done on a > virtual DVB driver for the Linux media subsystem. I am new to the media > subsystem and to kernel development in general. > > This driver aims to: > - Serve as template for new DVB driver writers > - Help userspace application writers in general > - Push fake audio/video to userspace for testing > purposes > - Push debug information to userspace via debugfs > The Virtual Digital TV Driver (vidtv) Any feedback on this patch series for Daniel. He has been waiting for reviews and feedback from media developers for a while now. Please review the patches and give him feedback and help him with next steps. thanks, -- Shuah
Em Fri, 24 Jul 2020 17:43:55 -0600 Shuah Khan <skhan@linuxfoundation.org> escreveu: > Hi Mauro, > > On 6/8/20 1:13 PM, Daniel W. S. Almeida wrote: > > From: "Daniel W. S. Almeida" <dwlsalmeida@gmail.com> > > > > This series is work in progress. It represents the current work done on a > > virtual DVB driver for the Linux media subsystem. I am new to the media > > subsystem and to kernel development in general. > > > > This driver aims to: > > - Serve as template for new DVB driver writers > > - Help userspace application writers in general > > - Push fake audio/video to userspace for testing > > purposes > > - Push debug information to userspace via debugfs > > The Virtual Digital TV Driver (vidtv) > > Any feedback on this patch series for Daniel. He has been waiting for > reviews and feedback from media developers for a while now. > > Please review the patches and give him feedback and help him with > next steps. I'll seek for some time to look and review them next week. What's the current status of it? Is it probing properly and working fine, or are there any known bugs at the code? Thanks, Mauro
From: "Daniel W. S. Almeida" <dwlsalmeida@gmail.com> This series is work in progress. It represents the current work done on a virtual DVB driver for the Linux media subsystem. I am new to the media subsystem and to kernel development in general. This driver aims to: - Serve as template for new DVB driver writers - Help userspace application writers in general - Push fake audio/video to userspace for testing purposes - Push debug information to userspace via debugfs The Virtual Digital TV Driver (vidtv) Background ---------- Vidtv is a virtual DVB driver that aims to serve as a reference for driver writers by serving as a template. It also validates the existing media DVB APIs, thus helping userspace application writers. Currently, it consists of: - A fake tuner driver, which will report a bad signal quality if the chosen frequency is too far away from a table of valid frequencies for a particular delivery system. - A fake demod driver, which will constantly poll the fake signal quality returned by the tuner, simulating a device that can lose/reacquire a lock on the signal depending on the CNR levels. - A fake bridge driver, which is the module responsible for modprobing the fake tuner and demod modules and implementing the demux logic. This module takes parameters at initialization that will dictate how the simulation behaves. - Code reponsible for encoding a valid MPEG Transport Stream, which is then passed to the bridge driver. This fake stream contains some hardcoded content. For now, we have a single, audio-only channel containing a single MPEG Elementary Stream, which in turn contains a SMPTE 302m encoded sine-wave. Note that this particular encoder was chosen because it is the easiest way to encode PCM audio data in a MPEG Transport Stream. Building vidtv -------------- vidtv is a test driver and thus is **not** enabled by default when compiling the kernel. In order to enable compilation of vidtv: - Enable **DVB_TEST_DRIVERS**, then - Enable **DVB_VIDTV** When compiled as a module, expect the following .ko files: - dvb_vidtv_tuner.ko - dvb_vidtv_demod.ko - dvb_vidtv_bridge.ko Running vidtv ------------- When compiled as a module, run:: modprobe dvb_vidtv_bridge That's it! The bridge driver will initialize the tuner and demod drivers as part of its own initialization. You can optionally define some command-line arguments to vidtv, see the documentation for more info. Testing vidtv with v4l-utils ============================ Start by installing v4l-utils and then modprobing vidtv:: modprobe dvb_vidtv_bridge If the driver is OK, it should load and its probing code will run. This will pull in the tuner and demod drivers. Using dvb-fe-tool ----------------- The first step to check whether the demod loaded successfully is to run:: $ dvb-fe-tool This should return what is currently set up at the demod struct, i.e.:: static const struct dvb_frontend_ops vidtv_demod_ops = { .delsys = { SYS_DVBT, SYS_DVBT2, SYS_DVBC_ANNEX_A, SYS_DVBS, SYS_DVBS2, }, .info = { .name = "Dummy demod for DVB-T/T2/C/S/S2", .frequency_min_hz = 51 * MHz, .frequency_max_hz = 2150 * MHz, .frequency_stepsize_hz = 62500, .frequency_tolerance_hz = 29500 * kHz, .symbol_rate_min = 1000000, .symbol_rate_max = 45000000, .caps = FE_CAN_FEC_1_2 | FE_CAN_FEC_2_3 | FE_CAN_FEC_3_4 | FE_CAN_FEC_4_5 | FE_CAN_FEC_5_6 | FE_CAN_FEC_6_7 | FE_CAN_FEC_7_8 | FE_CAN_FEC_8_9 | FE_CAN_QAM_16 | FE_CAN_QAM_64 | FE_CAN_QAM_32 | FE_CAN_QAM_128 | FE_CAN_QAM_256 | FE_CAN_QAM_AUTO | FE_CAN_QPSK | FE_CAN_FEC_AUTO | FE_CAN_INVERSION_AUTO | FE_CAN_TRANSMISSION_MODE_AUTO | FE_CAN_GUARD_INTERVAL_AUTO | FE_CAN_HIERARCHY_AUTO, } .... Using dvb-scan -------------- In order to tune into a channel and read the PSI tables, we can use dvb-scan. For this, one should provide a configuration file known as a 'scan file', here's an example:: [Channel] FREQUENCY = 330000000 MODULATION = QAM/AUTO SYMBOL_RATE = 6940000 INNER_FEC = AUTO DELIVERY_SYSTEM = DVBC/ANNEX_A NOTE: The parameters depend on the video standard you're testing. NOTE: Vidtv is a fake driver and does not validate much of the information in the scan file. Just specifying 'FREQUENCY' and 'DELIVERY_SYSTEM' should be enough for DVB-T/DVB-T2. For DVB-S/DVB-C however, you should also provide 'SYMBOL_RATE'. Assuming this channel is named 'channel.conf', you can then run:: $ dvbv5-scan dresden_dvbc_channel.conf Using dvb-zap ------------- dvbv5-zap is a command line tool that can be used to record MPEG-TS to disk. The typical use is to tune into a channel and put it into record mode. The example below - which is taken from the documentation - illustrates that:: $ dvbv5-zap -c dvb_channel.conf "trilhas sonoras" -r using demux '/dev/dvb/adapter0/demux0' reading channels from file 'dvb_channel.conf' service has pid type 05: 204 tuning to 573000000 Hz audio pid 104 dvb_set_pesfilter 104 Lock (0x1f) Quality= Good Signal= 100.00% C/N= -13.80dB UCB= 70 postBER= 3.14x10^-3 PER= 0 DVR interface '/dev/dvb/adapter0/dvr0' can now be opened The channel can be watched by playing the contents of the DVR interface, with some player that recognizes the MPEG-TS format, such as *mplayer* or *vlc*. By playing the contents of the stream one can visually inspect the workings of vidtv, e.g.:: $ mplayer /dev/dvb/adapter0/dvr0 Changes in v7: Collapse commits (10->4) Add RestructuredText documentation Fix checkpatch warnings Add calls to dvb_module_release and i2c_del_adapter in the bridge driver Add kernel-doc comments Changes in v6: Addressed the following issues: - Makefile was not actually compiling everything; - The bridge driver should be a platform driver; - There are lots of warnings and other errors produced by the driver. Changes in v5: Removed all calls to WARN_ON in favor of pr_warn_ratelimited Add a #define for pr_fmt Reworked the byte swapping logic for big/little endian support: big endian fields now prepended with __beXX for 'sparse' checks bitfields now laid in reverse order if LITTLE_ENDIAN_BITFIELD is set media: vidtv: implement a tuner driver Return -EINVAL instead of -1 in vidtv_tuner_check_frequency_shift media: vidtv: implement a demodulator driver Add POLL_THRD_TIME #define Implement dvb_frontend_ops as a single struct instead of three media: vidtv: move config structs into a separate header Removed this commit, configs are now in vidtv_tuner.h and vidtv_demod.h media: vidtv: add a bridge driver module_param: all fs permissions set to 0 removed param 'chosen_delsys' module_param: removed "optional" string: all module_params are optional renamed vidtv_bridge -> vidtv_bridg: so the source code and module names are different media: vidtv: add wrappers for memcpy and memset Added kernel-docs write address is now computed internally media: vidtv: add MPEG TS common code Drop packets if the buffer is full media: vidtv: implement a PSI generator Removed vidtv_psi_ts_psi_write_stuffing() Forcibly align misaligned buffers Drop packets if buffer is full media: vidtv: implement a PES packetizer Remove vidtv_extract_bits() in favor of GENMASK() and bitwise & Forcibly align misaligned buffers media: vidtv: Implement a SMPTE 302M encoder Added kernel-docs for struct vidtv_encoder media: vidtv: Add a MPEG Transport Stream Multiplexer Added check for minimum and maximum buffer size. Drop packets if buffer is full Changes in v4: Added a PES packetizer Implemented a minimum version of the SMPTE 302m encoder for AES3 audio Fixed endianness in the PSI generator, converting fields to big endian where applicable Added a minimal TS mux abstraction Changes in v3: Added a bridge driver Renamed the driver to vidtv Renamed/reworked commits into smaller pieces Moved the driver into its own directory Fixed the code for the signal strength in the tuner Removed useless enums in the tuner driver (e.g. lock_status, power_status...) Reworked the logic for the poll_snr thread in the demodulator driver Moved MPEG related code to the bridge driver, as it controls the demux logic Changed literals to #defines, used sizeof in place of integer literals when computing the size of PSI structs Moved the MPEG PSI tables to the heap to reduce stack space usage Now using usleep_range in place of msleep_interruptible in the MPEG TS thread Wrapped memcpy and memset to protect against buffer overflow when writing to the MPEG TS buffer. Changes in v2: Attempted not to break assignments into multiple lines as much as possible. Code now passes checkpatch strict mode media: dvb_dummy_tuner: implement driver skeleton Changed snr values to mili db Return value from 0-100 to indicate how far off the requested frequency is from a valid one Use the frequency shift to interpolate between 34dB and 10dB if we can not match against the SNR lookup table Remove sleep calls for suspend/resume Fix memcpy call for the config struct media: dvb_dummy_fe.c: lose TS lock on bad snr Randomly recover the TS lock if the signal quality improves media: dvb_dummy_fe.c: write PSI information into DMX buffer Split the patch into multiple header/source files Hexadecimal literals are now lower case Prefer short function names / reduce function signatures Add #defines for constants when computing section lengths Change signature for functions that take a dummy channel as argument (i.e. channels* is now channels[NUM_CHANNELS]) Daniel W. S. Almeida (4): media: vidtv: implement a tuner driver media: vidtv: implement a demodulator driver media: vidtv: add a bridge driver media: Documentation: vidtv: Add ReST documentation for vidtv .../driver-api/media/drivers/index.rst | 1 + .../driver-api/media/drivers/vidtv.rst | 415 ++++++ MAINTAINERS | 8 + drivers/media/test-drivers/Kconfig | 16 + drivers/media/test-drivers/Makefile | 1 + drivers/media/test-drivers/vidtv/Kconfig | 11 + drivers/media/test-drivers/vidtv/Makefile | 9 + .../media/test-drivers/vidtv/vidtv_bridge.c | 520 ++++++++ .../media/test-drivers/vidtv/vidtv_bridge.h | 60 + .../media/test-drivers/vidtv/vidtv_channel.c | 327 +++++ .../media/test-drivers/vidtv/vidtv_channel.h | 82 ++ .../media/test-drivers/vidtv/vidtv_common.c | 86 ++ .../media/test-drivers/vidtv/vidtv_common.h | 34 + .../media/test-drivers/vidtv/vidtv_demod.c | 440 +++++++ .../media/test-drivers/vidtv/vidtv_demod.h | 73 ++ .../media/test-drivers/vidtv/vidtv_encoder.h | 103 ++ drivers/media/test-drivers/vidtv/vidtv_mux.c | 437 +++++++ drivers/media/test-drivers/vidtv/vidtv_mux.h | 157 +++ drivers/media/test-drivers/vidtv/vidtv_pes.c | 450 +++++++ drivers/media/test-drivers/vidtv/vidtv_pes.h | 243 ++++ drivers/media/test-drivers/vidtv/vidtv_psi.c | 1160 +++++++++++++++++ drivers/media/test-drivers/vidtv/vidtv_psi.h | 674 ++++++++++ .../media/test-drivers/vidtv/vidtv_s302m.c | 643 +++++++++ .../media/test-drivers/vidtv/vidtv_s302m.h | 141 ++ drivers/media/test-drivers/vidtv/vidtv_ts.c | 165 +++ drivers/media/test-drivers/vidtv/vidtv_ts.h | 138 ++ .../media/test-drivers/vidtv/vidtv_tuner.c | 427 ++++++ .../media/test-drivers/vidtv/vidtv_tuner.h | 43 + 28 files changed, 6864 insertions(+) create mode 100644 Documentation/driver-api/media/drivers/vidtv.rst create mode 100644 drivers/media/test-drivers/vidtv/Kconfig create mode 100644 drivers/media/test-drivers/vidtv/Makefile create mode 100644 drivers/media/test-drivers/vidtv/vidtv_bridge.c create mode 100644 drivers/media/test-drivers/vidtv/vidtv_bridge.h create mode 100644 drivers/media/test-drivers/vidtv/vidtv_channel.c create mode 100644 drivers/media/test-drivers/vidtv/vidtv_channel.h create mode 100644 drivers/media/test-drivers/vidtv/vidtv_common.c create mode 100644 drivers/media/test-drivers/vidtv/vidtv_common.h create mode 100644 drivers/media/test-drivers/vidtv/vidtv_demod.c create mode 100644 drivers/media/test-drivers/vidtv/vidtv_demod.h create mode 100644 drivers/media/test-drivers/vidtv/vidtv_encoder.h create mode 100644 drivers/media/test-drivers/vidtv/vidtv_mux.c create mode 100644 drivers/media/test-drivers/vidtv/vidtv_mux.h create mode 100644 drivers/media/test-drivers/vidtv/vidtv_pes.c create mode 100644 drivers/media/test-drivers/vidtv/vidtv_pes.h create mode 100644 drivers/media/test-drivers/vidtv/vidtv_psi.c create mode 100644 drivers/media/test-drivers/vidtv/vidtv_psi.h create mode 100644 drivers/media/test-drivers/vidtv/vidtv_s302m.c create mode 100644 drivers/media/test-drivers/vidtv/vidtv_s302m.h create mode 100644 drivers/media/test-drivers/vidtv/vidtv_ts.c create mode 100644 drivers/media/test-drivers/vidtv/vidtv_ts.h create mode 100644 drivers/media/test-drivers/vidtv/vidtv_tuner.c create mode 100644 drivers/media/test-drivers/vidtv/vidtv_tuner.h