Re: [PATCH 1/2] SOUND: kill gameport bits

[Dmitry Torokhov]

Hi everyone,

On Thu, Aug 28, 2014 at 11:11:10PM +0200, Vojtech Pavlik wrote:
> On Thu, Aug 28, 2014 at 10:03:55PM +0200, Clemens Ladisch wrote:
> > Takashi Iwai wrote:
> > > did anyone test the patch at all...?
> > 
> > Appears to work.  The ymfpci gameport seems to be somewhat unreliable:
> > 
> >  analog.c: 100 out of 17347 reads (0%) on pci0000:06:06.1/gameport0 failed
> >  analog.c: 122 out of 1111 reads (10%) on pci0000:06:07.0/gameport0 failed
> 
> The analog.c gameport read routine is unreliable by design. 
> 
> The 558 chip is not an ADC, it's an one-shot timer from 1971. The analog
> position of the joystick is measured by timing bit changes on the
> gameport.
> 
> analog.c does that without disabling interrupts, as the read can take
> several milliseconds. analog.c instead detects when an interrupt influenced
> the measurement too much and retries.
> 
> The retries are counted and reported.
> 
> 10% is a largeish number, but still something the analog.c driver can
> cope with and give reliable results. 

So 10 years have passed since I tried to remove gameport support from
the kernel. I do not believe there were a lot of meaningful fixes.

Do we still want to keep this in the kernel or is it time for gameport
to retire?

Thanks.

-- 
Dmitry