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Message-ID: <ZrFEQkveaV6Q-Ayf@google.com>
Date: Mon, 5 Aug 2024 14:29:38 -0700
From: Dmitry Torokhov <dmitry.torokhov@...il.com>
To: Vojtech Pavlik <vojtech@...e.cz>
Cc: Clemens Ladisch <clemens@...isch.de>, Takashi Iwai <tiwai@...e.de>,
Andreas Mohr <andi@...as.de>, linux-input@...r.kernel.org,
linux-kernel@...r.kernel.org, Jiri Kosina <jkosina@...e.cz>
Subject: Re: [PATCH 1/2] SOUND: kill gameport bits
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
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