Re: [Bug 1959] New: cs46xx driver mmap_valid 0-->1 in kernel 2.6?

[Takashi Iwai <tiwai@suse.de>]

At Thu, 29 Jan 2004 08:56:55 +0200,
Janne Pikkarainen wrote:
> 
> Hello everyone, I just subscribed to this list...
> 
> At Tue, 27 Jan 2004 07:14:40 -0800,
> Martin J. Bligh wrote:
> >> 
> >> Is there a reason to keep mmap_valid=0 in cs46xx driver or is this a real bug? I
> >> haven't seen any new bugs with this patch applied, all the multimedia
> >> applications (mplayer, xine, xmms, noatun) keeps on working.
> 
> > cs46xx doesn't always support the direct hardware buffer.
> > Only in some cases with a proper period (fragment) numbers, it can
> > support the direct buffer access.  mmap_valid option forces the driver
> > to allow OSS apps the direct accessing via mmap.  This might not work
> > always, depending on the parameter the app uses.  Use at your own
> > risk.
> >
> > In short: it's not a real bug as long as mmap_valid=1 option works.
> > You had luck that your OSS apps (using mmap) seem working :)
> 
> If this is the case and if there are other applications affected by this
> than Enemy Territory and Wine mentioned in bug #1959, maybe the 
> "use mmap_valid 0/1" option should made selectable by the user in 
> kernel menuconfig? Of course with the proper "Caution: selecting 
> mmap_valid may cure some applications while hurting the others" warnings
> attached.
> 
> I mean, for example I thought for a long time that cs46xx is much more 
> badly broken in kernel 2.[56].x than it in reality seems to be. No new 
> sound bugs ever since I've applied this mmap_valid 0-->1 patch and I 
> think the first time I patched the driver was around 2.6.0-test1.
> 
> The sound card I have is Hercules SoundFusion Fortissimo III 7.1 
> (or something like that).

i myself have no objection to change the default for this option.
there are no many apps which use OSS mmap, except for quake & co. and
wine.

OTOH, i also feel that putting a single line in /etc/modprobe.conf
wouldn't be a hard job...


--
Takashi Iwai <tiwai@suse.de>		ALSA Developer - www.alsa-project.org