[linux-dvb] Re: driver files issue

[Holger Waechtler <holger@convergence.de>]

PerezJ@ee.nec.de wrote:
> Hello,
>
> I wonder if I can get an answer about the use of some files released under
> linux dvb V1.0.0.
> The files in  question are the ones located in the "driver" subdirectory.
> Files such
> dvb_frontend.c and dvb_frontend.h.
> The Linux DVB API document does not include any description of using these
> files.
>
> Could you please provide some feedback about this question as I have got
> the impression that these files
> are as "optional layer"  to support some hardware platform?
All files that are linked into dvb-core.o (these are the files in 
DVB/driver/ or dvb-kernel/linux/media/dvb/dvb-core/) are distributed 
under the terms of the GNU General Public License since they can get 
linked statically into the Linux kernel. This license policy was choosen 
in order to make improvements in the generic code useful for everybody.

Public Include files in DVB/include/linux/dvb/ and 
dvb-kernel/linux/include/linux/dvb/ are distributed under the terms of 
the GNU Lesser General Public License.

Lowlevel hardware drivers like the ones e.g. in 
linux/drivers/media/dvb/ttpci/, linux/drivers/media/dvb/bt8xx/, 
linux/drivers/media/dvb/b2c2/ can get developed under any license you 
need if you write them as dynamically loadable modules (binary only if 
you want) and set the MODULE_LICENSE() tag correctly to "Proprietary".

So you have basically two approaches to develop a proprietary driver:

Either you rewrite everything from scratch and don't use any source file 
beside the LGPL'd public includes in include/linux/dvb/. In this case 
you are not allowed to copy'n'paste and reuse any source code beside the 
API include files.

Or, much simpler: you write a loadable lowlevel hardware driver only 
like e.g. dvb-ttpci.o, dvb-ttusb-budget.o, dvb-bt8xx.o (all built in 
build-2.4 in case of a standalone build). In this case you reuse the 
dvb-core infrastructure (and you're kindly invited to improve things in 
the generic layer, please feed back changes to the community:) and need 
only to implement the hardware specific stuff.

Again you must not use any GPL'd code in your binary-only driver, but 
this should not be too critical, most code in the hardware drivers is 
not reusable anyway. In order to get an idea of what needs to get 
implemented for a hardware driver take a look for example in the bt8xx 
driver, the b2c2 driver or the ttpci or ttusb driver.

hope this answers your question,

Holger



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