V4L/DVB (10696): Remove outdated README for the flexcop-driver

This README escorted the skystar2-driver rewriting procedure. It describes the

state of the new flexcop-driver set and some internals are written down here

too.

This document hopefully describes things about the flexcop and its

device-offsprings. Goal was to write an easy-to-write and easy-to-read set of

drivers based on the skystar2.c and other information.

Remark: flexcop-pci.c was a copy of skystar2.c, but every line has been

touched and rewritten.

History & News

==============

  2005-04-01 - correct USB ISOC transfers (thanks to Vadim Catana)

General coding processing

=========================

We should proceed as follows (as long as no one complains):

0) Think before start writing code!

1) rewriting the skystar2.c with the help of the flexcop register descriptions

and splitting up the files to a pci-bus-part and a flexcop-part.

The new driver will be called b2c2-flexcop-pci.ko/b2c2-flexcop-usb.ko for the

device-specific part and b2c2-flexcop.ko for the common flexcop-functions.

2) Search for errors in the leftover of flexcop-pci.c (compare with pluto2.c

and other pci drivers)

3) make some beautification (see 'Improvements when rewriting (refactoring) is

done')

4) Testing the new driver and maybe substitute the skystar2.c with it, to reach

a wider tester audience.

5) creating an usb-bus-part using the already written flexcop code for the pci

card.

Idea: create a kernel-object for the flexcop and export all important

functions. This option saves kernel-memory, but maybe a lot of functions have

to be exported to kernel namespace.

Current situation

=================

0) Done :)

1) Done (some minor issues left)

2) Done

3) Not ready yet, more information is necessary

4) next to be done (see the table below)

5) USB driver is working (yes, there are some minor issues)

What seems to be ready?

-----------------------

1) Rewriting

1a) i2c is cut off from the flexcop-pci.c and seems to work

1b) moved tuner and demod stuff from flexcop-pci.c to flexcop-tuner-fe.c

1c) moved lnb and diseqc stuff from flexcop-pci.c to flexcop-tuner-fe.c

1e) eeprom (reading MAC address)

1d) sram (no dynamic sll size detection (commented out) (using default as JJ told me))

1f) misc. register accesses for reading parameters (e.g. resetting, revision)

1g) pid/mac filter (flexcop-hw-filter.c)

1i) dvb-stuff initialization in flexcop.c (done)

1h) dma stuff (now just using the size-irq, instead of all-together, to be done)

1j) remove flexcop initialization from flexcop-pci.c completely (done)

1l) use a well working dma IRQ method (done, see 'Known bugs and problems and TODO')

1k) cleanup flexcop-files (remove unused EXPORT_SYMBOLs, make static from

non-static where possible, moved code to proper places)

2) Search for errors in the leftover of flexcop-pci.c (partially done)

5a) add MAC address reading

5c) feeding of ISOC data to the software demux (format of the isochronous data

and speed optimization, no real error) (thanks to Vadim Catana)

What to do in the near future?

--------------------------------------

(no special order here)

5) USB driver

5b) optimize isoc-transfer (submitting/killing isoc URBs when transfer is starting)

Testing changes

---------------

O             = item is working

P             = item is partially working

X             = item is not working

N             = item does not apply here

<empty field> = item need to be examined

       | PCI                               | USB

item   | mt352 | nxt2002 | stv0299 | mt312 | mt352 | nxt2002 | stv0299 | mt312

-------+-------+---------+---------+-------+-------+---------+---------+-------

1a)    | O     |         |         |       | N     | N       | N       | N

1b)    | O     |         |         |       |       |         | O       |

1c)    | N     | N       |         |       | N     | N       | O       |

1d)    |                 O                 |                 O

1e)    |                 O                 |                 O

1f)    |                                   P

1g)    |                                   O

1h)    |                 P                 |

1i)    |                 O                 |                 N

1j)    |                 O                 |                 N

1l)    |                 O                 |                 N

2)     |                 O                 |                 N

5a)    |                 N                 |                 O

5b)*   |                 N                 |

5c)    |                 N                 |                 O

* - not done yet

Known bugs and problems and TODO

--------------------------------

1g/h/l) when pid filtering is enabled on the pci card

DMA usage currently:

  The DMA is splitted in 2 equal-sized subbuffers. The Flexcop writes to first

  address and triggers an IRQ when it's full and starts writing to the second

  address. When the second address is full, the IRQ is triggered again, and

  the flexcop writes to first address again, and so on.

  The buffersize of each address is currently 640*188 bytes.

  Problem is, when using hw-pid-filtering and doing some low-bandwidth

  operation (like scanning) the buffers won't be filled enough to trigger

  the IRQ. That's why:

  When PID filtering is activated, the timer IRQ is used. Every 1.97 ms the IRQ

  is triggered.  Is the current write address of DMA1 different to the one

  during the last IRQ, then the data is passed to the demuxer.

  There is an additional DMA-IRQ-method: packet count IRQ. This isn't

  implemented correctly yet.

  The solution is to disable HW PID filtering, but I don't know how the DVB

  API software demux behaves on slow systems with 45MBit/s TS.

Solved bugs :)

--------------

1g) pid-filtering (somehow pid index 4 and 5 (EMM_PID and ECM_PID) aren't

working)

SOLUTION: also index 0 was affected, because net_translation is done for

these indexes by default

5b) isochronous transfer does only work in the first attempt (for the Sky2PC

USB, Air2PC is working) SOLUTION: the flexcop was going asleep and never really

woke up again (don't know if this need fixes, see

flexcop-fe-tuner.c:flexcop_sleep)

NEWS: when the driver is loaded and unloaded and loaded again (w/o doing

anything in the while the driver is loaded the first time), no transfers take

place anymore.

Improvements when rewriting (refactoring) is done

=================================================

- split sleeping of the flexcop (misc_204.ACPI3_sig = 1;) from lnb_control

  (enable sleeping for other demods than dvb-s)

- add support for CableStar (stv0297 Microtune 203x/ALPS) (almost done, incompatibilities with the Nexus-CA)

Debugging

---------

- add verbose debugging to skystar2.c (dump the reg_dw_data) and compare it

  with this flexcop, this is important, because i2c is now using the

  flexcop_ibi_value union from flexcop-reg.h (do you have a better idea for

  that, please tell us so).

Everything which is identical in the following table, can be put into a common

flexcop-module.

		  PCI                  USB

-------------------------------------------------------------------------------

Different:

Register access:  accessing IO memory  USB control message

I2C bus:          I2C bus of the FC    USB control message

Data transfer:    DMA                  isochronous transfer

EEPROM transfer:  through i2c bus      not clear yet

Identical:

Streaming:                 accessing registers

PID Filtering:             accessing registers

Sram destinations:         accessing registers

Tuner/Demod:                     I2C bus

DVB-stuff:            can be written for common use

Acknowledgements (just for the rewriting part)

================

Bjarne Steinsbo thought a lot in the first place of the pci part for this code

sharing idea.

Andreas Oberritter for providing a recent PCI initialization template

(pluto2.c).

Boleslaw Ciesielski for pointing out a problem with firmware loader.

Vadim Catana for correcting the USB transfer.

comments, critics and ideas to linux-dvb@linuxtv.org.