Re: BUG: bttv does not load module ir-kbd-i2c for Hauppauge model 37284, rev B421

[Mauro Carvalho Chehab <mchehab@redhat.com>]

Em Sun, 06 Jan 2013 21:36:45 +0100
Frank Schäfer <fschaefer.oss@googlemail.com> escreveu:

> Am 05.01.2013 16:57, schrieb Mauro Carvalho Chehab:
> > Em Sat, 05 Jan 2013 15:00:18 +0100
> > Frank Schäfer <fschaefer.oss@googlemail.com> escreveu:
> >
> >> While we are at it ;) :
> >>
> >> [   15.280772] bttv: Bt8xx card found (0)
> >> [   15.281349] bttv: 0: Bt878 (rev 17) at 0000:01:08.0, irq: 18,
> >> latency: 32, mmio: 0xfdfff000
> >> [   15.281386] bttv: 0: detected: Hauppauge WinTV [card=10], PCI
> >> subsystem ID is 0070:13eb
> >> [   15.281391] bttv: 0: using: Hauppauge (bt878) [card=10,insmod option]
> >> [   15.283964] bttv: 0: Hauppauge/Voodoo msp34xx: reset line init [5]
> >> [   15.316043] tveeprom 4-0050: Hauppauge model 37284, rev B421, serial#
> >> 5111944
> >> [   15.316049] tveeprom 4-0050: tuner model is Philips FM1216 (idx 21,
> >> type 5)
> >> [   15.316054] tveeprom 4-0050: TV standards PAL(B/G) (eeprom 0x04)
> >> [   15.316059] tveeprom 4-0050: audio processor is MSP3410D (idx 5)
> >> [   15.316063] tveeprom 4-0050: has radio
> >> [   15.316066] bttv: 0: Hauppauge eeprom indicates model#37284
> >> [   15.316071] bttv: 0: tuner type=5
> >> [   16.178816] bttv: 0: registered device video0
> >> [   16.179071] bttv: 0: registered device vbi0
> >> [   16.180587] bttv: 0: registered device radio0
> >>
> >> When I load module ir-kbd-i2c manually:
> >>
> >> Registered IR keymap rc-hauppauge
> >> input: i2c IR (Hauppauge) as /devices/virtual/rc/rc0/input6
> >> rc0: i2c IR (Hauppauge) as /devices/virtual/rc/rc0
> >> ir-kbd-i2c: i2c IR (Hauppauge) detected at i2c-4/4-0018/ir0 [bt878 #0 [sw]]
> >>
> >> Remote control works fine then.
> > Yeah, this is a known misfeature of bttv, and very likely documented on
> > several wiki pages like those:
> > 	http://linuxtv.org/wiki/index.php/Remote_controllers-V4L
> > (btw, this wiki page is very likely outdated)
> > 	http://www.mythtv.org/wiki/Ir-kbd-i2c
> > 	http://www.linuxtv.org/wiki/index.php/Prolink_Pixelview_PlayTV_Pro
> >
> > I can't remember if this were always this way, or if this was
> > caused by the I2C core redesign (2006?). I think it was always like that,
> > and, as I2C comes with a cost (polling can affect video processing with
> > old machines), so, we decided to not do the auto-load on the older
> > drivers that weren't doing it already.
> 
> I'm not sure I understand you. Is it a misfeature or intentional ?

I think it was intentional, but I can't remember for sure. If it wasn't
intentional, its behavior changed when the I2C 'application type' flags
got removed (~5-6 years ago).

> Does polling 3 bytes every 100ms really affect the performance of video
> processing in a perceptable manner ?

On that time, yes. The big kernel lock were removed only on recent versions.
Also, CPUs/GPUs weren't that fast 7 years ago.

> > Btw, the fact that there's no clear indication about what bttv boards
> > require I2C made hard to remove the get_key codes from ir-kbd-i2c.
> 
> See my previous post, I thought the intention is to do the opposite.

No. We tried hard to identify what board were using what get_key code, and
moved the drivers specifics code to the driver.

> > It probably makes sense to add a "has_ir_i2c" field at bttv, add a flag
> > there at modprobe to prevent the autoload, and start tagging the boards
> > with I2C IR with such tag.
> 
> Without having looked into the code, it seems that the driver detects
> the i2c rc already without a board flag.
> Otherwise it wouldn't register the i2c device. Unfortunately, it doesn't
> display a message.

No. In the past (kernel 2.4 and upper), I2C bus used to work with 0-len
reads to scan the used I2C addresses. The I2C drivers like tuners, demods,
IR's etc used to register to the I2C core saying that they were to be used
on TV boards. The I2C logic binds them to the I2C bus driver when they were
detected, during the scanning process.

That's why it is so hard to know what boards are using I2C remotes, on
those older drivers.

We spent a lot of time seeking at the git logs to identify, before being
able to move the code away from ir-i2c-kbd.

> > If you care enough, feel free to send us such patch.
> 
> I care enough, but it has a low priority for me at the moment.
> 
> Regards,
> Frank
> 
> > Cheers,
> > Mauro
> 


-- 

Cheers,
Mauro