[Linux-kernel-mentees] [RFC, WIP, v6 00/10] media: vidtv: implement a virtual DVB driver
Shuah Khan
skhan at linuxfoundation.org
Thu May 28 23:57:06 UTC 2020
On 5/20/20 1:03 AM, Daniel W. S. Almeida wrote:
> From: "Daniel W. S. Almeida" <dwlsalmeida at 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
>
> This should currently be able to feed PSI and PCM audio data to
> userspace.
>
> I appreciate any feedback!
>
> 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 (10):
> media: vidtv: add Kconfig entry
> media: vidtv: implement a tuner driver
You can collapse patch 1 and 2. I don't see why you need two
separate patches.
> media: vidtv: implement a demodulator driver
> media: vidtv: add a bridge driver
> media: vidtv: add wrappers for memcpy and memset
> media: vidtv: add MPEG TS common code
> media: vidtv: implement a PSI generator
> media: vidtv: implement a PES packetizer
> media: vidtv: Implement a SMPTE 302M encoder
> media: vidtv: Add a MPEG Transport Stream Multiplexer
>
> arch/Kconfig | 2 +-
Why do you need this change. It is part of patch 04 with no
explanation on why this change is necessary.
> drivers/media/dvb-core/dvbdev.c | 1 +
Same here.
> drivers/media/test-drivers/Kconfig | 10 +
> 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 | 511 ++++++++
> .../media/test-drivers/vidtv/vidtv_bridge.h | 41 +
> .../media/test-drivers/vidtv/vidtv_channel.c | 339 ++++++
> .../media/test-drivers/vidtv/vidtv_channel.h | 66 ++
> .../media/test-drivers/vidtv/vidtv_common.c | 86 ++
> .../media/test-drivers/vidtv/vidtv_common.h | 34 +
> .../media/test-drivers/vidtv/vidtv_demod.c | 444 +++++++
> .../media/test-drivers/vidtv/vidtv_demod.h | 41 +
> .../media/test-drivers/vidtv/vidtv_encoder.h | 103 ++
> drivers/media/test-drivers/vidtv/vidtv_mux.c | 434 +++++++
> drivers/media/test-drivers/vidtv/vidtv_mux.h | 105 ++
> drivers/media/test-drivers/vidtv/vidtv_pes.c | 450 +++++++
> drivers/media/test-drivers/vidtv/vidtv_pes.h | 186 +++
> drivers/media/test-drivers/vidtv/vidtv_psi.c | 1055 +++++++++++++++++
> drivers/media/test-drivers/vidtv/vidtv_psi.h | 420 +++++++
> .../media/test-drivers/vidtv/vidtv_s302m.c | 636 ++++++++++
> .../media/test-drivers/vidtv/vidtv_s302m.h | 119 ++
> drivers/media/test-drivers/vidtv/vidtv_ts.c | 157 +++
> drivers/media/test-drivers/vidtv/vidtv_ts.h | 120 ++
> .../media/test-drivers/vidtv/vidtv_tuner.c | 408 +++++++
> .../media/test-drivers/vidtv/vidtv_tuner.h | 26 +
> 27 files changed, 5814 insertions(+), 1 deletion(-)
> 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
>
thanks,
-- Shuah
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