[Linux-kernel-mentees] [RFC, WIP, v3 0/6] media: vidtv: implement a virtual DVB driver

Daniel W. S. Almeida dwlsalmeida at gmail.com
Mon Apr 6 23:20:49 UTC 2020

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 applies on top of this branch
for now, as these changes have not been applied to the media tree yet.
The changes in this branch have reorganized where test drivers go in
the subsystem. The dummy driver written by Emard was left untouched.

As for vidtv, we currently have a tuner driver, a demodulator driver, a
bridge driver and some MPEG PSI code. This should be, therefore, a
minimum viable example for what this driver intends to become in the

I appreciate any feedback given. Thank you.

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 (6):
  media: vidtv: add Kconfig entry
  media: vidtv: implement a tuner driver
  media: vidtv: implement a demodulator driver
  media: vidtv: implement a PSI generator
  media: vidtv: move config structs into a common header
  media: vidtv: add a bridge driver

 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     |   6 +
 .../media/test_drivers/vidtv/vidtv_bridge.c   | 736 ++++++++++++++
 .../media/test_drivers/vidtv/vidtv_bridge.h   |  51 +
 .../media/test_drivers/vidtv/vidtv_common.c   |  44 +
 .../media/test_drivers/vidtv/vidtv_common.h   | 105 ++
 .../media/test_drivers/vidtv/vidtv_demod.c    | 493 +++++++++
 .../media/test_drivers/vidtv/vidtv_demod.h    |  34 +
 drivers/media/test_drivers/vidtv/vidtv_psi.c  | 960 ++++++++++++++++++
 drivers/media/test_drivers/vidtv/vidtv_psi.h  | 294 ++++++
 .../media/test_drivers/vidtv/vidtv_tuner.c    | 403 ++++++++
 13 files changed, 3148 insertions(+)
 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_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_psi.c
 create mode 100644 drivers/media/test_drivers/vidtv/vidtv_psi.h
 create mode 100644 drivers/media/test_drivers/vidtv/vidtv_tuner.c


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