linux-kernel - Re: [PATCH] mips/ad1843: convert time to jiffies HZ independent

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Message-ID: <s5hpp4xgqsf.wl-tiwai@suse.de>
Date:	Mon, 15 Jun 2015 13:22:08 +0200
From:	Takashi Iwai <tiwai@...e.de>
To:	Nicholas Mc Guire <der.herr@...r.at>
Cc:	Nicholas Mc Guire <hofrat@...dl.org>,
	Jaroslav Kysela <perex@...ex.cz>, alsa-devel@...a-project.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mips/ad1843: convert time to jiffies HZ independent

At Sun, 14 Jun 2015 19:16:59 +0200,
Nicholas Mc Guire wrote:
> 
> On Sun, 14 Jun 2015, Takashi Iwai wrote:
> 
> > At Sun, 14 Jun 2015 10:20:59 +0200,
> > Nicholas Mc Guire wrote:
> > > 
> > > PI compliance scanning with coccinelle flagged:
> > > ./sound/mips/ad1843.c:503:2-32: WARNING: 
> > > 	timeout (5) seems HZ dependent
> > > 
> > > This was introduced in 'commit 862c2c0a61c5 ("ALSA: ALSA driver for SGI O2
> > > audio board")'. schedule_timeout_interruptible() expects a timeout in
> > > jiffies so the numeric constant makes the effective timeout HZ dependent.
> > > Simply put it through msecs_to_jiffies() to make it HZ independent.
> > > 
> > > Signed-off-by: Nicholas Mc Guire <hofrat@...dl.org>
> > > ---
> > > 
> > > The loop here is bounded by 500 jiffies and it does not seem reasonable that
> > > it would loop 10 times faster on HZ=1000 configs over HZ=100 configs. The
> > > conversion via msecs_to_jiffies(5) ensures that it will loop at most 100
> > > times for all configs of HZ which seems reasonable (to me) but needs to be
> > > checked by someone that knows the details of this driver. 
> > 
> > Using 5ms looks reasonable for this case.  However,
> > schedule_timeout_interruptible() isn't.  This is a loop that won't
> > break.  So, the best would be to replace it with msleep() or its
> > friends.
> > 
> > > Note that the CONFIG_SND_PCM_OSS dependency was not listed in the 
> > > Depends on: in Kconfig (which it probably should)
> > 
> > Why at all?  It has nothing to do with OSS.
> >
> the procedure to see the problem I used was
> (linux-next 20150612)
> make ip32_defconfig ARCH=mips
> make menuconfig ARCH=mips
>   Device Drivers
>     ...
>     <M> Sound card support  --->
>         <M>   Advanced Linux Sound Architecture  --->
>             [*]   MIPS sound devices  --->
>                   <M>   SGI O2 Audio
> 
> compiling fails with:
>   MODPOST 95 modules
> ERROR: "snd_pcm_period_elapsed" [sound/mips/snd-sgi-o2.ko] undefined!
> ERROR: "snd_pcm_set_ops" [sound/mips/snd-sgi-o2.ko] undefined!
> ERROR: "snd_pcm_lib_get_vmalloc_page" [sound/mips/snd-sgi-o2.ko] undefined!
> ERROR: "snd_pcm_lib_ioctl" [sound/mips/snd-sgi-o2.ko] undefined!
> ERROR: "_snd_pcm_lib_alloc_vmalloc_buffer" [sound/mips/snd-sgi-o2.ko] undefined!
> ERROR: "snd_pcm_new" [sound/mips/snd-sgi-o2.ko] undefined!
> ERROR: "snd_pcm_lib_free_vmalloc_buffer" [sound/mips/snd-sgi-o2.ko] undefined!
> make[1]: *** [__modpost] Error 1
> make: *** [modules] Error 2
> 
> as the pcm_lib functions depend on SND_PCM I added that - So
> if I add the below patch the problem goes away and the module 
> build correclty - not saying that this is the right fix though
> (did not look into it in more detail yet)

Yes, this dependency fix is correct, and I queued your patch now.
But the dependency on CONFIG_SND_PCM_OSS is wrong.

A similar fix is needed for HAL2, and I fixed it, too.


thanks,

Takashi

> >From d9cb7d166613e6129f021a913f66f377f5ac56c0 Mon Sep 17 00:00:00 2001
> From: Nicholas Mc Guire <hofrat@...dl.org>
> Date: Sun, 14 Jun 2015 19:06:19 +0200
> Subject: [PATCH] ALSA: let SND_SGI_O2 select SND_PCM
> 
> Signed-off-by: Nicholas Mc Guire <hofrat@...dl.org>
> ---
>  sound/mips/Kconfig |    1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/sound/mips/Kconfig b/sound/mips/Kconfig
> index d2f615a..7875af0 100644
> --- a/sound/mips/Kconfig
> +++ b/sound/mips/Kconfig
> @@ -12,6 +12,7 @@ if SND_MIPS
>  config SND_SGI_O2
>  	tristate "SGI O2 Audio"
>  	depends on SGI_IP32
> +	select SND_PCM
>          help
>                  Sound support for the SGI O2 Workstation. 
>  
> -- 
> 1.7.10.4
> 
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