3ed8a31cb3
add acknowledgements Signed-off-by: Patrick Boettcher <pb@linuxtv.org> Signed-off-by: Johannes Stezenbach <js@linuxtv.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
285 lines
9.6 KiB
Plaintext
285 lines
9.6 KiB
Plaintext
This README escorted the skystar2-driver rewriting procedure. It describes the
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state of the new flexcop-driver set and some internals are written down here
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too.
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How to do something in here?
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============================
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make -f Makefile.t
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make -C ../build-2.6
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./in.sh # load the drivers
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./rm.sh # unload the drivers
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Please read this file, if you want to contribute.
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This document hopefully describes things about the flexcop and its
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device-offsprings. Goal is to write a easy-to-write and easy-to-read set of
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drivers based on the skystar2.c and other information.
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This directory is temporary. It is used for rewriting the skystar2.c and to
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create shared code, which then can be used by the usb box as well.
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Remark: flexcop-pci.c was a copy of skystar2.c, but every line has been
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touched and rewritten.
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General coding processing
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=========================
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We should proceed as follows (as long as no one complains):
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0) Think before start writing code!
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1) rewriting the skystar2.c with the help of the flexcop register descriptions
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and splitting up the files to a pci-bus-part and a flexcop-part.
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The new driver will be called b2c2-flexcop-pci.ko/b2c2-flexcop-usb.ko for the
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device-specific part and b2c2-flexcop.ko for the common flexcop-functions.
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2) Search for errors in the leftover of flexcop-pci.c (compare with pluto2.c
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and other pci drivers)
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3) make some beautification (see 'Improvements when rewriting (refactoring) is
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done')
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4) Testing the new driver and maybe substitute the skystar2.c with it, to reach
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a wider tester audience.
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5) creating an usb-bus-part using the already written flexcop code for the pci
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card.
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Idea: create a kernel-object for the flexcop and export all important
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functions. This option saves kernel-memory, but maybe a lot of functions have
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to be exported to kernel namespace.
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Current situation
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=================
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0) Done :)
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1) Done (some minor issues left)
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2) Done
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3) Not ready yet, more information is necessary
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4) next to be done (see the table below)
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5) USB driver is working (yes, there are some minor issues)
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What seems to be ready?
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-----------------------
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1) Rewriting
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1a) i2c is cut off from the flexcop-pci.c and seems to work
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1b) moved tuner and demod stuff from flexcop-pci.c to flexcop-tuner-fe.c
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1c) moved lnb and diseqc stuff from flexcop-pci.c to flexcop-tuner-fe.c
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1e) eeprom (reading MAC address)
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1d) sram (no dynamic sll size detection (commented out) (using default as JJ told me))
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1f) misc. register accesses for reading parameters (e.g. resetting, revision)
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1g) pid/mac filter (flexcop-hw-filter.c)
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1i) dvb-stuff initialization in flexcop.c (done)
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1h) dma stuff (now just using the size-irq, instead of all-together, to be done)
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1j) remove flexcop initialization from flexcop-pci.c completely (done)
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1l) use a well working dma IRQ method (done, see 'Known bugs and problems and TODO')
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1k) cleanup flexcop-files (remove unused EXPORT_SYMBOLs, make static from
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non-static where possible, moved code to proper places)
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2) Search for errors in the leftover of flexcop-pci.c (partially done)
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5a) add MAC address reading
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What to do in the near future?
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--------------------------------------
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(no special order here)
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5) USB driver
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5b) optimize isoc-transfer (submitting/killing isoc URBs when transfer is starting)
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5c) feeding of ISOC data to the software demux (format of the isochronous data
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and speed optimization, no real error)
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Testing changes
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---------------
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O = item is working
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P = item is partially working
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X = item is not working
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N = item does not apply here
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<empty field> = item need to be examined
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| PCI | USB
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item | mt352 | nxt2002 | stv0299 | mt312 | mt352 | nxt2002 | stv0299 | mt312
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-------+-------+---------+---------+-------+-------+---------+---------+-------
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1a) | O | | | | N | N | N | N
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1b) | O | | | | | | O |
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1c) | N | N | | | N | N | O |
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1d) | O | O
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1e) | O | O
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1f) | P
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1g) | O
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1h) | P |
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1i) | O | N
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1j) | O | N
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1l) | O | N
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2) | O | N
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5a) | N | O
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5b)* | N |
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5c)* | N |
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* - not done yet
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Known bugs and problems and TODO
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--------------------------------
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1g/h/l) when pid filtering is enabled on the pci card
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DMA usage currently:
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The DMA is splitted in 2 equal-sized subbuffers. The Flexcop writes to first
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address and triggers an IRQ when it's full and starts writing to the second
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address. When the second address is full, the IRQ is triggered again, and
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the flexcop writes to first address again, and so on.
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The buffersize of each address is currently 640*188 bytes.
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Problem is, when using hw-pid-filtering and doing some low-bandwidth
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operation (like scanning) the buffers won't be filled enough to trigger
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the IRQ. That's why:
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When PID filtering is activated, the timer IRQ is used. Every 1.97 ms the IRQ
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is triggered. Is the current write address of DMA1 different to the one
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during the last IRQ, then the data is passed to the demuxer.
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There is an additional DMA-IRQ-method: packet count IRQ. This isn't
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implemented correctly yet.
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The solution is to disable HW PID filtering, but I don't know how the DVB
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API software demux behaves on slow systems with 45MBit/s TS.
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Solved bugs :)
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--------------
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1g) pid-filtering (somehow pid index 4 and 5 (EMM_PID and ECM_PID) aren't
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working)
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SOLUTION: also index 0 was affected, because net_translation is done for
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these indexes by default
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5b) isochronous transfer does only work in the first attempt (for the Sky2PC USB,
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Air2PC is working)
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SOLUTION: the flexcop was going asleep and never really woke up again (don't
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know if this need fixes, see flexcop-fe-tuner.c:flexcop_sleep)
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Improvements when rewriting (refactoring) is done
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=================================================
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- split sleeping of the flexcop (misc_204.ACPI3_sig = 1;) from lnb_control
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(enable sleeping for other demods than dvb-s)
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- add support for CableStar (stv0297 Microtune 203x/ALPS)
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Debugging
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---------
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- add verbose debugging to skystar2.c (dump the reg_dw_data) and compare it
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with this flexcop, this is important, because i2c is now using the
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flexcop_ibi_value union from flexcop-reg.h (do you have a better idea for
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that, please tell us so).
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Everything which is identical in the following table, can be put into a common
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flexcop-module.
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PCI USB
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-------------------------------------------------------------------------------
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Different:
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Register access: accessing IO memory USB control message
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I2C bus: I2C bus of the FC USB control message
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Data transfer: DMA isochronous transfer
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EEPROM transfer: through i2c bus not clear yet
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Identical:
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Streaming: accessing registers
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PID Filtering: accessing registers
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Sram destinations: accessing registers
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Tuner/Demod: I2C bus
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DVB-stuff: can be written for common use
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Restrictions:
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============
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We need to create a bus-specific-struct and a flexcop-struct.
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bus-specific-struct:
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struct flexcop_pci
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...
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struct flexcop_usb
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...
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struct flexcop_device {
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void *bus_specific; /* container for bus-specific struct */
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...
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}
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PCI i2c can read/write max 4 bytes at a time, USB can more
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Functions
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=========
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Syntax
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------
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- Flexcop functions will be called "flexcop(_[a-z0-9]+)+" and exported as such
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if needed.
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- Flexcop-device functions will be called "flexcop_device(_[a-z0-9]+)+" and
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exported as such if needed.
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- Both will be compiled to b2c2-flexcop.ko and their source can be found in the
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flexcop*.[hc]
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Callbacks and exports
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---------------------
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Bus-specific functions will be given as callbacks (function pointers) to the
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flexcop-module. (within the flexcop_device-struct)
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Initialization process
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======================
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b2c2-flexcop.ko is loaded
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b2c2-flexcop-<bus>.ko is loaded
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suppose a device is found:
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malloc flexcop and the bus-specific variables (via flexcop_device_malloc)
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fill the bus-specific variable
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fill the flexcop variable (especially the bus-specific callbacks)
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bus-specific initialization
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- ...
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do the common initialization (via flexcop_device_initialize)
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- reset the card
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- determine flexcop type (II, IIB, III)
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- hw_filters (bus dependent)
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- 0x204
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- set sram size
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- create the dvb-stuff
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- create i2c stuff
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- frontend-initialization
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done
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bus specific:
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- media_destination (this and the following 3 are bus specific)
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- cai_dest
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- cao_dest
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- net_destination
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Bugs fixed while rewriting the driver
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=====================================
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- EEPROM access (to read the MAC address) was fixed to death some time last
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year. (fixed here and in skystar2.c) (Bjarne, this was the piece of code
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(fix-chipaddr) we were wondering about)
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Acknowledgements (just for the rewriting part)
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================
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Bjarne Steinsbo thought a lot in the first place of the pci part for this code
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sharing idea.
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Andreas Oberritter for providing a recent PCI initialization template
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(pluto2.c).
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Boleslaw Ciesielski for pointing out a problem with firmware loader.
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Vadim Catana for correcting the USB transfer.
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comments, critics and ideas to linux-dvb@linuxtv.org or patrick.boettcher@desy.de
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