[linux-dvb] Announcement: new saa7146 driver core for the av7110 dvb driver

[Michael Hunold <hunold-ml@web.de>]

Hello all,

please let me introduce myself: my name is Michael Hunold and I'm the
original author of the saa7146 driver, on which Convergence has based
it's driver for the av7110 driver. My parts are only used for the
Video4Linux output for the full-featured dvb cards with on-board mpeg
decoder, I have nothing to do with the actual dvb driver or the dvb api
-- until now. 8-)

A little bit of history:

Convergence forked their av7110 driver from an early release of my
driver, which supported the Video4Linux-1 interface of the kernel.
Although the driver core was meant to be modular, it wasn't quite usable
out-of-the-box, and so the authors decided to hack changes directly into
the driver core.

Lately, the new Video4Linux-2 api made it into the kernel and the famous
bttv driver and the new saa7134 driver are already available for it.

In the meantime, I developped my saa7146 driver for analogue tv cards
further and ported it to the overhauled Video4Linux-2 api lately.
(have a look at http://www.mihu.de/linux/ for further informations)

Just about the time I planned to submit this new saa7146 driver core
plus the additional drivers to the kernel, the dvb av7110 driver was
added to the 2.5.x kernel series by Alan Cox and is available since
2.5.50 now in the official kernel.

Theoretically, it should be possible to have both drivers in the kernel
and they should not interfere each other.

But practically, this would be a really ugly hack: most likely both
drivers don't work together, it would mean massive code duplication and
fixing bugs in two drivers, when it could be done in one and -- this is
the worst for me -- both core drivers would carry *my* name in it.

So I recently contacted Hoger Wächtler at Convergence and asked if it
was possible to unify the two saa7146 driver cores again. He agreed and
so I began working on it.

I'm happy to announce, that the results are now available in the
"dvb-kernel" module of the CVS and can be tried for both 2.5.x kernels
by patching the kernel (as it was possible before) and for
2.4.x kernels by compiling the new driver as stand-alone modules.

The install instructions for 2.5.x kernels can be found in
dvb-kernel/README, the install instructions for 2.4.x kernels
are in dvb-kernel/build-2.4/README.

Please let me state the following explicitly:

The change of the saa7146 driver core does *NOT* mean that anything
related to the dvb-core, the dvb api or similar has changed. The changes
do *NOT* affect the way the dvb subsystem or all the dvb-tools work, so
all dvb applications *must* behave exactly the same.

I simply took the av7110 driver and put it 1:1 onto my saa7146 driver
core, and modified and extended the core to support some additional
stuff that was added by Convergence to my driver.

What has changed, however, is the support for the Video4Linux subsystem.
The driver is a Video4Linux-2 driver, but there is a system-wide
compatibility layer for "old" Video4Linux-1 applications. But, expect
problems with Video4Linux-1 applications that try to be "clever" when
using the Video4Linux-1 api.

Ok, I tried the driver myself for 2.4.18 and 2.5.52 with a Siemens DVB-S
1.3  and the tools from the apps directory and the most important
applications vdr and xawtv. It works flawlessly.

Please try out the new driver and report your problems to the
mailing-list. I'm especially interested in results with so-called budget
cards.

If you have problem with particular video applications, please tell me
about it. I'll have a look at it and try to adjust the compatibility
layer (if possible) or urge the author of the software to use
Video4Linux-2 instead... ;-)

Recent Video4Linux-1 applications should work, I tried "effectv" and
"tvtime" successfully for example. Currently, "tuxview" does not work
very good -- is anyone actually using it?

Expect that there are a few glitches here and there at the beginning,
but I'm trying to fix all problems asap.

Have fun
Michael Hunold.




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