DVB core enhancements - comments please?

Here is my list of needed DVB core related changes. Feel free to comment - what are not needed or what you would like to see instead. I will try to implement what I can (and what I like most interesting :).

general validly checking for demodulator callback input values
--------------------------------------------------
* currently each driver needs to validate those
* values are highly hooked up to used television standard
* we can do almost all validly checking inside core
* we can also check if call is possible to perform in given condition
* for example BER is not valid when demod is unlocked

suspend / resume support
--------------------------------------------------
* support is currently quite missing, all what is done is on interface drivers
* needs power management
* streaming makes it hard
* quite a lot work to get it working in case of straming is ongoing

use Kernel power management instead of own
--------------------------------------------------
* there seems to be Kernel services for power-management
* study if it is wise to use Kernel services instead of own
* own PM is still working very well, at least I dont know any problems

SDR - Softaware Defined Radio support DVB API
--------------------------------------------------
* http://comments.gmane.org/gmane.linux.drivers.video-input-infrastructure/44461
* there is existing devices that are SDR (RTL2832U "rtl-sdr")
* SDR is quite near what is digital TV streaming
* study what is needed
* new delivery system for frontend API called SDR?
* some core changes needed, like status (is locked etc)
* how about demuxer?
* stream conversion, inside Kernel?
* what are new parameters needed for DVB API?

DTMB standard support for DVB API
--------------------------------------------------
* it is Chinese DTV standard
* I already ran RFC but have been too busy for implementing it :]

LNA (low-noise amplifier) support for DVB API
--------------------------------------------------
* there is quite a lot of devices having LNA
* currently not supported => LNA is configured off typically

offer polling method for statistics
--------------------------------------------------
* many static counters could not be read as a "one go"
* typical cycle is : start measurement => wait => read counters
* some drivers starts own internal work-queue for polling (complexity)
* some drivers blocks IOCTL when taking measurement (bad)

fix frontend properties
--------------------------------------------------
* those has been broken since MFE => SFE change
* currently implemented as a properties per driver
* need to be properties per delivery system
* are broken because driver/chip could support multiple DTV standards

regards
Antti

Em 27-06-2012 21:33, Antti Palosaari escreveu:

Quoted 11 lines

SDR - Softaware Defined Radio support DVB API
--------------------------------------------------
* http://comments.gmane.org/gmane.linux.drivers.video-input-infrastructure/44461
* there is existing devices that are SDR (RTL2832U "rtl-sdr")
* SDR is quite near what is digital TV streaming
* study what is needed
* new delivery system for frontend API called SDR?
* some core changes needed, like status (is locked etc)
* how about demuxer?
* stream conversion, inside Kernel?
* what are new parameters needed for DVB API?

Let's not mix APIs: the radio control should use the V4L2 API, as this is not DVB. The V4L2 API has already everything needed for radio. The only missing part ther is the audio stream. However, there are a few drivers that provide audio via the radio device node, using read()/poll() syscalls, like pvrusb. On this specific driver, audio comes through a MPEG stream. As SDR provides audio on a different format, it could make sense to use VIDIOC_S_STD/VIDIOC_G_STD to set/retrieve the type of audio stream, for SDR, but maybe it better to just add capabilities flag at VIDIOC_QUERYCTL or VIDIOC_G_TUNER to indicate that the audio will come though the radio node and if the format is MPEG or SDR.

Quoted 14 lines · Mauro Carvalho Chehab

Em 27-06-2012 21:33, Antti Palosaari escreveu:

Quoted 4 lines

SDR - Softaware Defined Radio support DVB API
--------------------------------------------------
*
http://comments.gmane.org/gmane.linux.drivers.video-input-infrastructu

Quoted 8 lines

re/44461 * there is existing devices that are SDR (RTL2832U "rtl-sdr")
* SDR is quite near what is digital TV streaming
* study what is needed
* new delivery system for frontend API called SDR?
* some core changes needed, like status (is locked etc)
* how about demuxer?
* stream conversion, inside Kernel?
* what are new parameters needed for DVB API?

Quoted 11 lines

Let's not mix APIs: the radio control should use the V4L2 API, as this is not DVB. The V4L2 API has already everything needed for radio. The only missing part ther is the audio stream. However, there are a few drivers that provide audio via the radio device node, using read()/poll() syscalls, like pvrusb. On this specific driver, audio comes through a MPEG stream. As SDR provides audio on a different format, it could make sense to use VIDIOC_S_STD/VIDIOC_G_STD to set/retrieve the type of audio stream, for SDR, but maybe it better to just add capabilities flag at VIDIOC_QUERYCTL or VIDIOC_G_TUNER to indicate that the audio will come though the radio node and if the format is MPEG or SDR.

SDR is not a radio in mean of V4L2 analog audio radios. SDR can receive all kind of signals, analog audio, analog television, digital radio, digital television, cellular phones, etc. You can even receive DVB-T, but hardware I have is not capable to receive such wide stream.

That chip supports natively DVB-T TS but change be switched to SDR mode. Is it even possible to switch from DVB API (DVB-T delivery system) to V4L2 API at runtime?

Quoted 26 lines · On Friday 29 June 2012 08:03:16 Antti Palosaari wrote:

Quoted 14 lines · Mauro Carvalho Chehab

Em 27-06-2012 21:33, Antti Palosaari escreveu:

Quoted 4 lines

SDR - Softaware Defined Radio support DVB API
--------------------------------------------------
*
http://comments.gmane.org/gmane.linux.drivers.video-input-infrastructu

Quoted 8 lines

re/44461 * there is existing devices that are SDR (RTL2832U "rtl-sdr")
* SDR is quite near what is digital TV streaming
* study what is needed
* new delivery system for frontend API called SDR?
* some core changes needed, like status (is locked etc)
* how about demuxer?
* stream conversion, inside Kernel?
* what are new parameters needed for DVB API?

Quoted 11 lines

Let's not mix APIs: the radio control should use the V4L2 API, as this is not DVB. The V4L2 API has already everything needed for radio. The only missing part ther is the audio stream. However, there are a few drivers that provide audio via the radio device node, using read()/poll() syscalls, like pvrusb. On this specific driver, audio comes through a MPEG stream. As SDR provides audio on a different format, it could make sense to use VIDIOC_S_STD/VIDIOC_G_STD to set/retrieve the type of audio stream, for SDR, but maybe it better to just add capabilities flag at VIDIOC_QUERYCTL or VIDIOC_G_TUNER to indicate that the audio will come though the radio node and if the format is MPEG or SDR.

Quoted 8 lines

SDR is not a radio in mean of V4L2 analog audio radios. SDR can receive all kind of signals, analog audio, analog television, digital radio, digital television, cellular phones, etc. You can even receive DVB-T, but hardware I have is not capable to receive such wide stream.

That chip supports natively DVB-T TS but change be switched to SDR mode. Is it even possible to switch from DVB API (DVB-T delivery system) to V4L2 API at runtime?

It could be possible that neither the DVB-API nor the V4L2 API is the right user-interface for such devices. The output of such devices is the acquisition of raw (digitalized) data of a signal and here signal is meant in the sense of anything which can be digitalized (e.g.: sensors, tuners, ADCs).

Such device will surely be have a device-specific (user-space?) library to do the post/pre-processing before putting this data into a generic format.

That said, IMO, the rtl-sdr driver should sit on the DVB-API. Maybe V4L2 provides a device-specific control path (to configure the hardware) if not somewhere else, or something new needs to be created.

That said, IMO, the rtl-sdr driver should sit on the DVB-API. Maybe V4L2

Quoted 26 lines · Mauro Carvalho Chehab

Quoted 14 lines

Em 27-06-2012 21:33, Antti Palosaari escreveu:

Quoted 4 lines

SDR - Softaware Defined Radio support DVB API
--------------------------------------------------
*
http://comments.gmane.org/gmane.linux.drivers.video-input-infrastructu

Quoted 8 lines

re/44461 * there is existing devices that are SDR (RTL2832U "rtl-sdr")
* SDR is quite near what is digital TV streaming
* study what is needed
* new delivery system for frontend API called SDR?
* some core changes needed, like status (is locked etc)
* how about demuxer?
* stream conversion, inside Kernel?
* what are new parameters needed for DVB API?

Quoted 11 lines

Let's not mix APIs: the radio control should use the V4L2 API, as this is not DVB. The V4L2 API has already everything needed for radio. The only missing part ther is the audio stream. However, there are a few drivers that provide audio via the radio device node, using read()/poll() syscalls, like pvrusb. On this specific driver, audio comes through a MPEG stream. As SDR provides audio on a different format, it could make sense to use VIDIOC_S_STD/VIDIOC_G_STD to set/retrieve the type of audio stream, for SDR, but maybe it better to just add capabilities flag at VIDIOC_QUERYCTL or VIDIOC_G_TUNER to indicate that the audio will come though the radio node and if the format is MPEG or SDR.

Quoted 8 lines

SDR is not a radio in mean of V4L2 analog audio radios. SDR can receive all kind of signals, analog audio, analog television, digital radio, digital television, cellular phones, etc. You can even receive DVB-T, but hardware I have is not capable to receive such wide stream.

That chip supports natively DVB-T TS but change be switched to SDR mode. Is it even possible to switch from DVB API (DVB-T delivery system) to V4L2 API at runtime?

It could be possible that neither the DVB-API nor the V4L2 API is the right user-interface for such devices. The output of such devices is the acquisition of raw (digitalized) data of a signal and here signal is meant in the sense of anything which can be digitalized (e.g.: sensors, tuners, ADCs).

Such device will surely be have a device-specific (user-space?) library to do the post/pre-processing before putting this data into a generic format.

Quoted 3 lines

That said, IMO, the rtl-sdr driver should sit on the DVB-API. Maybe V4L2 provides a device-specific control path (to configure the hardware) if not somewhere else, or something new needs to be created.

*argl* I wanted to say, ... should _not_ sit on the DVB-API...

Em 29-06-2012 08:24, Patrick Boettcher escreveu:

Quoted 36 lines · On Friday 29 June 2012 08:03:16 Antti Palosaari wrote:

Quoted 26 lines · Mauro Carvalho Chehab

Quoted 14 lines

Em 27-06-2012 21:33, Antti Palosaari escreveu:

Quoted 4 lines

SDR - Softaware Defined Radio support DVB API
--------------------------------------------------
*
http://comments.gmane.org/gmane.linux.drivers.video-input-infrastructu

Quoted 8 lines

re/44461 * there is existing devices that are SDR (RTL2832U "rtl-sdr")
* SDR is quite near what is digital TV streaming
* study what is needed
* new delivery system for frontend API called SDR?
* some core changes needed, like status (is locked etc)
* how about demuxer?
* stream conversion, inside Kernel?
* what are new parameters needed for DVB API?

Quoted 11 lines

Let's not mix APIs: the radio control should use the V4L2 API, as this is not DVB. The V4L2 API has already everything needed for radio. The only missing part ther is the audio stream. However, there are a few drivers that provide audio via the radio device node, using read()/poll() syscalls, like pvrusb. On this specific driver, audio comes through a MPEG stream. As SDR provides audio on a different format, it could make sense to use VIDIOC_S_STD/VIDIOC_G_STD to set/retrieve the type of audio stream, for SDR, but maybe it better to just add capabilities flag at VIDIOC_QUERYCTL or VIDIOC_G_TUNER to indicate that the audio will come though the radio node and if the format is MPEG or SDR.

Quoted 8 lines

SDR is not a radio in mean of V4L2 analog audio radios. SDR can receive all kind of signals, analog audio, analog television, digital radio, digital television, cellular phones, etc. You can even receive DVB-T, but hardware I have is not capable to receive such wide stream.

That chip supports natively DVB-T TS but change be switched to SDR mode. Is it even possible to switch from DVB API (DVB-T delivery system) to V4L2 API at runtime?

Quoted 8 lines

It could be possible that neither the DVB-API nor the V4L2 API is the right user-interface for such devices. The output of such devices is the acquisition of raw (digitalized) data of a signal and here signal is meant in the sense of anything which can be digitalized (e.g.: sensors, tuners, ADCs).

Such device will surely be have a device-specific (user-space?) library to do the post/pre-processing before putting this data into a generic format.

That's one more reason why using the V4L2 API is better: at the V4L2 API, the output format is represented by a 32 bits unique code. There are several standard fourcc codes there, plus several proprietary formats represented. The decoding between the proprietary formats is done via libv4l. Libv4l can be used with any pre-compiled userspace application, via LD_PRELOAD, although almost all V4L2 userspace applications[1] are using the libv4l to decode data. Adding SDR decoding there should not be hard.

[1] Radio applications don't use it yet, as almost all radio devices output audio via ALSA API, so some work will be needed there to add SDR radio support.

Quoted 3 lines

Quoted 3 lines

That said, IMO, the rtl-sdr driver should sit on the DVB-API. Maybe V4L2 provides a device-specific control path (to configure the hardware) if not somewhere else, or something new needs to be created.

Quoted 1 line

*argl* I wanted to say, ... should _not_ sit on the DVB-API...

Agreed. Tuning with the V4L2 API is more direct, as doesn't have any threads looking for DVB demod status, in order to do frequency zig-zag.

It also have support for hardware frequency scanning, which can be an interesting feature if supported.

Quoted 67 lines

Em 29-06-2012 08:24, Patrick Boettcher escreveu:

Quoted 36 lines · On Friday 29 June 2012 08:03:16 Antti Palosaari wrote:

Quoted 26 lines · Mauro Carvalho Chehab

Quoted 14 lines

Em 27-06-2012 21:33, Antti Palosaari escreveu:

Quoted 4 lines

SDR - Softaware Defined Radio support DVB API
--------------------------------------------------
*
http://comments.gmane.org/gmane.linux.drivers.video-input-infrastructu

Quoted 8 lines

re/44461 * there is existing devices that are SDR (RTL2832U "rtl-sdr")
* SDR is quite near what is digital TV streaming
* study what is needed
* new delivery system for frontend API called SDR?
* some core changes needed, like status (is locked etc)
* how about demuxer?
* stream conversion, inside Kernel?
* what are new parameters needed for DVB API?

Quoted 11 lines

Let's not mix APIs: the radio control should use the V4L2 API, as this is not DVB. The V4L2 API has already everything needed for radio. The only missing part ther is the audio stream. However, there are a few drivers that provide audio via the radio device node, using read()/poll() syscalls, like pvrusb. On this specific driver, audio comes through a MPEG stream. As SDR provides audio on a different format, it could make sense to use VIDIOC_S_STD/VIDIOC_G_STD to set/retrieve the type of audio stream, for SDR, but maybe it better to just add capabilities flag at VIDIOC_QUERYCTL or VIDIOC_G_TUNER to indicate that the audio will come though the radio node and if the format is MPEG or SDR.

Quoted 8 lines

SDR is not a radio in mean of V4L2 analog audio radios. SDR can receive all kind of signals, analog audio, analog television, digital radio, digital television, cellular phones, etc. You can even receive DVB-T, but hardware I have is not capable to receive such wide stream.

That chip supports natively DVB-T TS but change be switched to SDR mode. Is it even possible to switch from DVB API (DVB-T delivery system) to V4L2 API at runtime?

Quoted 8 lines

It could be possible that neither the DVB-API nor the V4L2 API is the right user-interface for such devices. The output of such devices is the acquisition of raw (digitalized) data of a signal and here signal is meant in the sense of anything which can be digitalized (e.g.: sensors, tuners, ADCs).

Such device will surely be have a device-specific (user-space?) library to do the post/pre-processing before putting this data into a generic format.

That's one more reason why using the V4L2 API is better: at the V4L2 API, the output format is represented by a 32 bits unique code. There are several standard fourcc codes there, plus several proprietary formats represented. The decoding between the proprietary formats is done via libv4l. Libv4l can be used with any pre-compiled userspace application, via LD_PRELOAD, although almost all V4L2 userspace applications[1] are using the libv4l to decode data. Adding SDR decoding there should not be hard.

[1] Radio applications don't use it yet, as almost all radio devices output audio via ALSA API, so some work will be needed there to add SDR radio support.

Quoted 5 lines

Quoted 3 lines

That said, IMO, the rtl-sdr driver should sit on the DVB-API. Maybe V4L2 provides a device-specific control path (to configure the hardware) if not somewhere else, or something new needs to be created.

*argl* I wanted to say, ... should _not_ sit on the DVB-API...

Agreed. Tuning with the V4L2 API is more direct, as doesn't have any threads looking for DVB demod status, in order to do frequency zig-zag.

Quoted 2 lines

It also have support for hardware frequency scanning, which can be an interesting feature if supported.

OK, I have now played (too) many hours. Looking existing code and testing. But I cannot listen even simple FM-radio station. What are most famous / best radio applications ? I tried gnomeradio, gqradio and fmscan...

That is USB radio based si470x chipset.

Jul  3 00:12:18 localhost kernel: [27988.288783] usb 5-2: New USB device found, idVendor=10c5, idProduct=819a
Jul  3 00:12:18 localhost kernel: [27988.288787] usb 5-2: New USB device strings: Mfr=1, Product=2, SerialNumber=0
Jul  3 00:12:18 localhost kernel: [27988.288789] usb 5-2: Manufacturer: www.rding.cn
Jul  3 00:12:18 localhost udevd[409]: specified group 'plugdev' unknown
Jul  3 00:12:18 localhost kernel: [27988.310751] radio-si470x 5-2:1.2: DeviceID=0x1242 ChipID=0x060c
Jul  3 00:12:18 localhost kernel: [27988.310754] radio-si470x 5-2:1.2: This driver is known to work with firmware version 15,
Jul  3 00:12:18 localhost kernel: [27988.310756] radio-si470x 5-2:1.2: but the device has firmware version 12.
Jul  3 00:12:18 localhost kernel: [27988.312750] radio-si470x 5-2:1.2: software version 1, hardware version 7
Jul  3 00:12:18 localhost kernel: [27988.312753] radio-si470x 5-2:1.2: This driver is known to work with software version 7,
Jul  3 00:12:18 localhost kernel: [27988.312755] radio-si470x 5-2:1.2: but the device has software version 1.
Jul  3 00:12:18 localhost kernel: [27988.312756] radio-si470x 5-2:1.2: If you have some trouble using this driver,
Jul  3 00:12:18 localhost kernel: [27988.312757] radio-si470x 5-2:1.2: please report to V4L ML at [email protected]

regards
Antti

Quoted 1 line

That is USB radio based si470x chipset.

Well, I don't have any si470x device here.

It should be noticed that radio applications in general don't open the
alsa devices to get audio, as old devices used to have a cable to wire
at the audio adapter.

I bet that this device uses snd-usb-audio module for audio. So, you may
need to use aplayer/arecord in order to listen, with a syntax similar to:

    arecord -D hw:1,0 -r 32000 -c 2 -f S16_LE
| aplay -

The -r 32000 is for 32 kHz.

Quoted 1 line

Jul  3 00:12:18 localhost kernel: [27988.288783]

usb 5-2: New USB device found, idVendor=10c5,
idProduct=819a

Quoted 1 line

Jul  3 00:12:18 localhost kernel: [27988.288787]

usb 5-2: New USB device strings: Mfr=1, Product=2, SerialNumber=0

Quoted 1 line

Jul  3 00:12:18 localhost kernel: [27988.288789]

usb 5-2: Manufacturer: www.rding.cn

Quoted 1 line

Jul  3 00:12:18 localhost udevd[409]: specified

group 'plugdev' unknown

Quoted 1 line

Jul  3 00:12:18 localhost kernel: [27988.310751]

radio-si470x 5-2:1.2: DeviceID=0x1242 ChipID=0x060c

Quoted 1 line

Jul  3 00:12:18 localhost kernel: [27988.310754]

radio-si470x 5-2:1.2: This driver is known to work with firmware version 15,

Quoted 1 line

Jul  3 00:12:18 localhost kernel: [27988.310756]

radio-si470x 5-2:1.2: but the device has firmware version 12.

Quoted 1 line

Jul  3 00:12:18 localhost kernel: [27988.312750]

radio-si470x 5-2:1.2: software version 1, hardware version 7

Quoted 1 line

Jul  3 00:12:18 localhost kernel: [27988.312753]

radio-si470x 5-2:1.2: This driver is known to work with software version 7,

Quoted 1 line

Jul  3 00:12:18 localhost kernel: [27988.312755]

radio-si470x 5-2:1.2: but the device has software version 1.

Em 02-07-2012 18:27, Antti Palosaari escreveu:

Quoted 3 lines

OK, I have now played (too) many hours. Looking existing code and testing. But I cannot listen even simple FM-radio station. What are most famous / best radio applications ? I tried gnomeradio, gqradio and fmscan...

That is USB radio based si470x chipset.

Well, I don't have any si470x device here.

It should be noticed that radio applications in general don't open the alsa devices to get audio, as old devices used to have a cable to wire at the audio adapter.

I bet that this device uses snd-usb-audio module for audio. So, you may need to use aplayer/arecord in order to listen, with a syntax similar to:

	arecord -D hw:1,0 -r 32000 -c 2 -f S16_LE | aplay -

The -r 32000 is for 32 kHz.

In my case, I prefer to use "radio" aplication that comes with xawtv. It shouldn't be hard to patch it to also create the audio playback command there, as the code for that is already there at xawtv3 tree, and it is used by xawtv.

I'll see if I can write a patch for that today.

Quoted 13 lines

Em 27-06-2012 21:33, Antti Palosaari escreveu:

Quoted 11 lines

SDR - Softaware Defined Radio support DVB API
--------------------------------------------------
* http://comments.gmane.org/gmane.linux.drivers.video-input-infrastructure/44461
* there is existing devices that are SDR (RTL2832U "rtl-sdr")
* SDR is quite near what is digital TV streaming
* study what is needed
* new delivery system for frontend API called SDR?
* some core changes needed, like status (is locked etc)
* how about demuxer?
* stream conversion, inside Kernel?
* what are new parameters needed for DVB API?

Quoted 9 lines

Let's not mix APIs: the radio control should use the V4L2 API, as this is not DVB. The V4L2 API has already everything needed for radio. The only missing part ther is the audio stream. However, there are a few drivers that provide audio via the radio device node, using read()/poll() syscalls, like pvrusb. On this specific driver, audio comes through a MPEG stream. As SDR provides audio on a different format, it could make sense to use VIDIOC_S_STD/VIDIOC_G_STD to set/retrieve the type of audio stream, for SDR, but maybe it better to just add capabilities flag at VIDIOC_QUERYCTL or VIDIOC_G_TUNER to indicate that the audio will come though the radio node and if the format is MPEG or SDR.

SDR is not a radio in mean of V4L2 analog audio radios.

SDR can receive all kind of signals, analog audio, analog television, digital radio, digital television, cellular phones, etc. You can even receive DVB-T, but hardware I have is not capable to receive such wide stream.

That chip supports natively DVB-T TS but change be switched to SDR mode. Is it even possible to switch from DVB API (DVB-T delivery system) to V4L2 API at runtime?

Em 29-06-2012 02:03, Antti Palosaari escreveu:

Quoted 24 lines · Mauro Carvalho Chehab

Quoted 13 lines

Em 27-06-2012 21:33, Antti Palosaari escreveu:

Quoted 11 lines

SDR - Softaware Defined Radio support DVB API
--------------------------------------------------
* http://comments.gmane.org/gmane.linux.drivers.video-input-infrastructure/44461
* there is existing devices that are SDR (RTL2832U "rtl-sdr")
* SDR is quite near what is digital TV streaming
* study what is needed
* new delivery system for frontend API called SDR?
* some core changes needed, like status (is locked etc)
* how about demuxer?
* stream conversion, inside Kernel?
* what are new parameters needed for DVB API?

Quoted 9 lines

Let's not mix APIs: the radio control should use the V4L2 API, as this is not DVB. The V4L2 API has already everything needed for radio. The only missing part ther is the audio stream. However, there are a few drivers that provide audio via the radio device node, using read()/poll() syscalls, like pvrusb. On this specific driver, audio comes through a MPEG stream. As SDR provides audio on a different format, it could make sense to use VIDIOC_S_STD/VIDIOC_G_STD to set/retrieve the type of audio stream, for SDR, but maybe it better to just add capabilities flag at VIDIOC_QUERYCTL or VIDIOC_G_TUNER to indicate that the audio will come though the radio node and if the format is MPEG or SDR.

Quoted 1 line

SDR is not a radio in mean of V4L2 analog audio radios.

Why not? There's nothing at V4L2 API that limits it to analog, otherwise it couldn't be used by digital cameras.

Quoted 3 lines

SDR can receive all kind of signals, analog audio, analog television, digital radio, digital television, cellular phones, etc. You can even receive DVB-T, but hardware I have is not capable to receive such wide stream.

The V4L2 API has everything to control receivers. What it doesn't have (and it doesn't make sense to have, as such thing would just duplicate existing features at DVB API) are the per delivery-system specific demodulator properties and PID filtering.

Quoted 2 lines

That chip supports natively DVB-T TS but change be switched to SDR mode. Is it even possible to switch from DVB API (DVB-T delivery system) to V4L2 API at runtime?

Yes. There are lots of drivers that do that. There are even a few that allow to control the frontend and demod via DVB API and to receive streams via V4L2 mmap or read API.

Here is my list of needed DVB core related changes. Feel free to comment - what are not needed or what you would like to see instead. I will try to implement what I can (and what I like most interesting :).

suspend / resume support
--------------------------------------------------
* support is currently quite missing, all what is done is on interface drivers
* needs power management
* streaming makes it hard
* quite a lot work to get it working in case of straming is ongoing

My suspend / resume patch implemented "Kaffeine continues viewing channel after resume".
Some of the ideas could be still useful:
http://www.spinics.net/lists/linux-dvb/msg19651.html

Rest of this email has a more thorough description.

Regards,
Marko Ristola

Quoted 4 lines · Antti Palosaari

Here is my list of needed DVB core related changes. Feel free to comment - what are not needed or what you would like to see instead. I will try to implement what I can (and what I like most interesting :).

...

Quoted 7 lines

suspend / resume support
--------------------------------------------------
* support is currently quite missing, all what is done is on interface drivers
* needs power management
* streaming makes it hard
* quite a lot work to get it working in case of straming is ongoing

I've implemented Suspend/Resume for Mantis cu1216 in 2007 (PCI DVB-C device):
Kaffeine continued viewing the channel after resume.
When Tuner was idle too long, it was powered off too.

According to Manu Abraham at that time, somewhat smaller patch would have sufficed.
That patch contais nonrelated fixes too, and won't compile now.

Here is the reference (with Manu's answer):
Start of the thread: http://www.spinics.net/lists/linux-dvb/msg19532.html
The patch: http://www.spinics.net/lists/linux-dvb/msg19651.html
Manu's answer: http://www.spinics.net/lists/linux-dvb/msg19668.html

Thoughts about up-to-date implementation
- Bridge (PCI) device must implement suspend/resume callbacks.

- Frontend might need some change (power off / power on callbacks)?

- "save Tuner / DMA transfer state to memory" might be addable to dvb_core.
- Bridge device supporting suspend/resume needs to have a (non-regression) fallback for (frontend) devices that don't have a full tested
"Kaffeine works"
suspend/resume implementation yet.

- What changes encrypted channels need?

Moikka Marko,

Hmm, I did some initial suspend / resume changes for DVB USB when I rewrote it recently. On suspend, it just kills all ongoing urbs used for streaming. And on resume it resubmit those urbs in order to resume streaming. It just works as it doesn't hang computer anymore. What I tested applications continued to show same television channels on resume.

The problem for that solution is that it does not have any power management as power management is DVB-core responsibility. So it continues eating current because chips are not put sleep and due to that those DVB-core changes are required.

Quoted 2 lines

- What changes encrypted channels need?

I think none?

regards
Antti

Moikka Antti.

Quoted 2 lines · Antti Palosaari

Moikka Marko,

-- snip --

Quoted 7 lines

Hmm, I did some initial suspend / resume changes for DVB USB when I rewrote it recently. On suspend, it just kills all ongoing urbs used for streaming. And on resume it resubmit those urbs in order to resume streaming. It just works as it doesn't hang computer anymore. What I tested applications continued to show same television channels on resume.

Quoted 4 lines

The problem for that solution is that it does not have any power management as power management is DVB-core responsibility. So it continues eating current because chips are not put sleep and due to that those DVB-core changes are required.

I think that runtime (RT) frontend power saving is a different thing. It isn't necessarily suspend/resume thing.

I implemented runtime Frontend power saving in 2007 on that patch I referenced.
I used dvb-core's existing functionality. Maybe this concept is applicable for you too.

I added into Mantis bridge device initialization following functions:
+ mantis->fe->ops.tuner_ops.sleep =
mantis_dvb_tuner_sleep;
+ mantis->fe->ops.tuner_ops.init =
mantis_dvb_tuner_init;
tuner_ops.{sleep,init} modification had to be the last one.

I maintained in mantis->has_power the frontend's power status. Maybe I could have read the active status from PCI context too.

The concept was something like:
- dvb-core has responsibility to call tuner_ops.sleep() and tuner_ops.init() when applicable.
- Mantis PCI Bridge driver (or specific USB driver) has responsibility to provide sleep and init implementations for the specific device.
- Mantis bridge device will do the whole task of frontend power management, by calling Frontend's
tear down / initialization functions when necessary.

Quoted 3 lines

Quoted 1 line

- What changes encrypted channels need?

I think none?

Morjens!

I am now working with that suspend/resume/power-management, as I got LNA issues resolved.

Quoted 16 lines · Marko Ristola

Moikka Antti.

Quoted 2 lines · Antti Palosaari

Moikka Marko,

-- snip --

Quoted 8 lines

Hmm, I did some initial suspend / resume changes for DVB USB when I rewrote it recently. On suspend, it just kills all ongoing urbs used for streaming. And on resume it resubmit those urbs in order to resume streaming. It just works as it doesn't hang computer anymore. What I tested applications continued to show same television channels on resume.

Quoted 7 lines

Quoted 4 lines

The problem for that solution is that it does not have any power management as power management is DVB-core responsibility. So it continues eating current because chips are not put sleep and due to that those DVB-core changes are required.

I think that runtime (RT) frontend power saving is a different thing. It isn't necessarily suspend/resume thing.

Yes it is different thing (DVB-core runtime power-management). But as there is currently implemented .init() and .sleep() callbacks both frontend and tuner for power management I don't see why not to use those for suspend and resume too.

Quoted 15 lines

I implemented runtime Frontend power saving in 2007 on that patch I referenced.
I used dvb-core's existing functionality. Maybe this concept is applicable for you too.

I added into Mantis bridge device initialization following functions:
+ mantis->fe->ops.tuner_ops.sleep =
mantis_dvb_tuner_sleep;
+ mantis->fe->ops.tuner_ops.init =
mantis_dvb_tuner_init;
tuner_ops.{sleep,init} modification had to be the last one.

I maintained in mantis->has_power the frontend's power status. Maybe I could have read the active status from PCI context too.

Quoted 8 lines

The concept was something like:
- dvb-core has responsibility to call tuner_ops.sleep() and tuner_ops.init() when applicable.
- Mantis PCI Bridge driver (or specific USB driver) has responsibility to provide sleep and init implementations for the specific device.
- Mantis bridge device will do the whole task of frontend power management, by calling Frontend's
tear down / initialization functions when necessary.

I looked it and reads your discussion too. That code seem never ended up for Mantis.

But the idea is just basically same: use existing sleep() calls to put device sleep on suspend and on resume use init() to wake-up again. You stored existing parameters inside driver state and retuned using those when set_frontend() get NULL as a parameter. Things has changed a little after that and now those parameters are stored already in dvb-frontend cache - which means a little less work for driver.

Quoted 3 lines

Quoted 3 lines

Quoted 1 line

- What changes encrypted channels need?

I think none?

So after all, what I think currently, is:
* bridge sets and forwards .suspend() callback to dvb-core
* bridge sets and forwards .resume() callback to dvb-core
* on suspend, dvb-core puts device sleep
* on resume, dvb-core wake-ups device and inits tune (parameters are in cache already)

Clearly, put hardware sleep similarly as in case frontend is in sleep, but keep userland interface alive (frontend, demux, etc).