[linux-dvb] Re: [video4linux-cvs] [hg:v4l-dvb] Add support for Opera S1- DVB-USB

Mauro Carvalho Chehab mchehab at infradead.org
Fri Apr 20 14:07:36 CEST 2007


Em Sex, 2007-04-20 às 13:53 +0200, Johannes Stezenbach escreveu:
> On Fri, Apr 20, 2007, Mauro Carvalho Chehab wrote:
> > Argh! Too much flood for two simple defines!
> 
> I _think_ the point Mike was driving at is that there
> is an established coding pattern of having a
> 
> struct foo_config {
> 	u8 i2c_addr;
> 	...
> };
> 
> If you use that then the #define is (at least) superflous,
> "foo_tuner.i2c_addr = 0x62;" does the job.
> 
> If you don't use it, then the #define increases readability.
> However, experience shows that soon enough there'll be
> another similar device with a different i2c_addr so it makes
> sense to use the pattern right from the start.

Ok, this makes sense. 

The point that I'm trying to argue is that this specific driver is full
of magic values. I suspect that the author doesn't have datasheets for
the chipsets inside the board. Almost all the driver are doing some
magic, making hard to understand precisely what are being programmed at
the device.

The proper solution would be if somebody with a datasheet could send a
patch replacing those magic by register aliases, making easier to get a
picture. While we don't have such patch, IMO, it is better to try to
generate some hints for each possible magic at the driver. Hopefully,
some day we will have enough knowledge to understand all.
 
Cheers,
Mauro




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