Re: pcm_multi broken in alsa-lib - no duplex mode with jackd

[Simon Lewis <simon.lewis@mnet-online.de>]

Nice one Takashi!

I tested the new alsa-lib snapshot on a  "virgin" openSUSE 10.2 today.
Jack started with no errors in duplex mode with my sound card using
separate pcm_multi functions to group the inputs and outputs respectively.

Naturally John Rigg and the others at Jack-Devel will test the
corrections more thoroughly but for me at least it appears to be working
fine.

Best regards, Simon

Simon Lewis
Lautensackstrasse 12
80687 München

Tel.: +49 89 57869412
Fax: +49 89 57869411
e-mail: simon.lewis@mnet-online.de

Takashi Iwai wrote:
> At Tue, 13 Mar 2007 10:05:06 +0100,
> Simon Lewis wrote:
>   
>> Dear Takashi
>>
>> Can I use the two patchs with alsa-lib 1.0.13 ?
>>     
>
> Might work, but don't try.  It simply increases another unknown
> factors.  First try the latest HG version with the patch to confirm
> that it works.  After that, try any version you like.
>
>   
>> If yes, please let me know the terminal commands assuming that I have
>> already cd'ed into the unpacked alsa-lib folder.
>>     
>
> 	% patch -p1 -i this_patch
>
> In doubt, wait until tomorrow, then grab the latest daily snapshot
> tarball from 
> 	ftp://ftp.suse.com/pub/projects/alsa/snapshot/
>
> which will include the all patches.
>
>
> Takashi
>   
>> Takashi Iwai schrieb:
>>     
>>> At Tue, 13 Mar 2007 00:46:52 +0100,
>>> I wrote:
>>>   
>>>       
>>>> At Sat, 10 Mar 2007 14:17:13 +0000,
>>>> John Rigg wrote:
>>>>     
>>>>         
>>>>> On Fri, Mar 09, 2007 at 05:38:34PM +0100, Takashi Iwai wrote:
>>>>>       
>>>>>           
>>>>>> At Thu, 8 Mar 2007 21:51:28 +0000,
>>>>>> John Rigg wrote:
>>>>>>         
>>>>>>             
>>>>>>> On Thu, Mar 08, 2007 at 07:58:23PM +0100, Takashi Iwai wrote:
>>>>>>>           
>>>>>>>               
>>>>>>>> At Thu, 08 Mar 2007 18:16:02 +0100,
>>>>>>>> Simon Lewis wrote:
>>>>>>>>             
>>>>>>>>                 
>>>>>>>>> Many JACK users have successfully used the following patch:
>>>>>>>>>
>>>>>>>>> http://www.sound-man.co.uk/linuxaudio/pcm_multi-patch
>>>>>>>>>               
>>>>>>>>>                   
>>>>>>>> Well, the patch is no real fix.  It's likely a workaround for JACK,
>>>>>>>> though.  Someone has to take time to track down this bug more deeply.
>>>>>>>>             
>>>>>>>>                 
>>>>>>> True, the patch is just a workaround for JACK. However, I would
>>>>>>> argue that most users of pcm_multi are probably JACK users.
>>>>>>>           
>>>>>>>               
>>>>>> No, multi plugin is used in many surround PCM definitions as default.
>>>>>> It's pretty hidden, but multi streams are no rare case.
>>>>>>         
>>>>>>             
>>>>> I hadn't noticed that. Thanks for pointing it out (and thank you for
>>>>> looking at this problem!)
>>>>>
>>>>>       
>>>>>           
>>>>>>> Surely adding code that breaks something for the majority of users (no
>>>>>>> matter how correct that code is in isolation) is not a good thing.
>>>>>>>           
>>>>>>>               
>>>>>> Sure.  However, this code addition was for bugfixes of major other use
>>>>>> cases like above, IIRC.  The regression should be avoided and should
>>>>>> be fixed.  But the point is, we (at least, I) haven't been enough
>>>>>> informed, unfortunately (or simply burried in a big TODO list :)
>>>>>>
>>>>>> Now, let's back to the original problem:  Could someone give a pointer
>>>>>> describing for this problem, or just explain a bit details here?
>>>>>> I vaguely remember but not precisely at all now...
>>>>>> I'm willing to dig down after knowing how I can reproduce the bug.
>>>>>>         
>>>>>>             
>>>>> To summarise, using multiple sound cards with pcm_multi and jackd
>>>>> no longer works in duplex mode ever since extra linking code was
>>>>> added to pcm_multi.c in alsa-lib-1.0.9rc1.
>>>>>
>>>>> Trying to start jackd in duplex fails with a poll timeout message.
>>>>> It still works in playback-only or capture-only modes.
>>>>> The lack of duplex operation makes overdubbing in a recording studio,
>>>>> for example, impossible.
>>>>>
>>>>> A configuration which produces the problem with two ice1712 cards
>>>>> set up as a 16 channel multi device is shown here:
>>>>> http://www.sound-man.co.uk/linuxaudio/ice1712multi.html
>>>>>
>>>>> With the .asoundrc described in the above link the following
>>>>> command fails with a poll timeout message:
>>>>>
>>>>> jackd -d alsa -P multi_playback -C multi_capture
>>>>>
>>>>> The following still work:
>>>>> jackd -d alsa -P multi_playback
>>>>> jackd -d alsa -C multi_capture
>>>>>       
>>>>>           
>>>> OK, played a bit around this bug.  A temporary fix is attached below.
>>>> It's applied to HG tree now, too.  Please give it a try.
>>>>
>>>> The real fix will come later...
>>>>     
>>>>         
>>> More complete fix is below.  Apply after the previous patch.
>>> (Or more easily use the HG version.)
>>>
>>>
>>> Takashi
>>>
>>>
>>> # HG changeset patch
>>> # User tiwai
>>> # Date 1173750753 -3600
>>> # Node ID 4883f0ba21df769cea44345f35dcdd3b6214b8e7
>>> # Parent  78c78fa6c41db913484d6e3cff2f1e31e5fc6075
>>> More better fix for linked start/stop
>>>
>>> Instead of link_fd, more generic callback link_slaves is introduced.
>>> This is called for linking the slave streams as the source to the
>>> given master stream.
>>>
>>> diff -r 78c78fa6c41d -r 4883f0ba21df src/pcm/pcm.c
>>> --- a/src/pcm/pcm.c	Tue Mar 13 00:40:22 2007 +0100
>>> +++ b/src/pcm/pcm.c	Tue Mar 13 02:52:33 2007 +0100
>>> @@ -6313,15 +6313,6 @@ snd_pcm_sframes_t snd_pcm_mmap_commit(sn
>>>  }
>>>  
>>>  #ifndef DOC_HIDDEN
>>> -
>>> -int _snd_pcm_link_descriptors(snd_pcm_t *pcm, int *fds, int count,
>>> -			      int (**failed)(snd_pcm_t *, int))
>>> -{
>>> -	assert(pcm);
>>> -	if (pcm->fast_ops->link_fd)
>>> -		return pcm->fast_ops->link_fd(pcm, fds, count, failed);
>>> -	return -ENOSYS;
>>> -}
>>>  
>>>  int _snd_pcm_poll_descriptor(snd_pcm_t *pcm)
>>>  {
>>> diff -r 78c78fa6c41d -r 4883f0ba21df src/pcm/pcm_dmix.c
>>> --- a/src/pcm/pcm_dmix.c	Tue Mar 13 00:40:22 2007 +0100
>>> +++ b/src/pcm/pcm_dmix.c	Tue Mar 13 02:52:33 2007 +0100
>>> @@ -757,8 +757,8 @@ static snd_pcm_fast_ops_t snd_pcm_dmix_f
>>>  	.rewind = snd_pcm_dmix_rewind,
>>>  	.forward = snd_pcm_dmix_forward,
>>>  	.resume = snd_pcm_direct_resume,
>>> -	.link_fd = NULL,
>>>  	.link = NULL,
>>> +	.link_slaves = NULL,
>>>  	.unlink = NULL,
>>>  	.writei = snd_pcm_mmap_writei,
>>>  	.writen = snd_pcm_mmap_writen,
>>> diff -r 78c78fa6c41d -r 4883f0ba21df src/pcm/pcm_dshare.c
>>> --- a/src/pcm/pcm_dshare.c	Tue Mar 13 00:40:22 2007 +0100
>>> +++ b/src/pcm/pcm_dshare.c	Tue Mar 13 02:52:33 2007 +0100
>>> @@ -562,8 +562,8 @@ static snd_pcm_fast_ops_t snd_pcm_dshare
>>>  	.rewind = snd_pcm_dshare_rewind,
>>>  	.forward = snd_pcm_dshare_forward,
>>>  	.resume = snd_pcm_direct_resume,
>>> -	.link_fd = NULL,
>>>  	.link = NULL,
>>> +	.link_slaves = NULL,
>>>  	.unlink = NULL,
>>>  	.writei = snd_pcm_mmap_writei,
>>>  	.writen = snd_pcm_mmap_writen,
>>> diff -r 78c78fa6c41d -r 4883f0ba21df src/pcm/pcm_dsnoop.c
>>> --- a/src/pcm/pcm_dsnoop.c	Tue Mar 13 00:40:22 2007 +0100
>>> +++ b/src/pcm/pcm_dsnoop.c	Tue Mar 13 02:52:33 2007 +0100
>>> @@ -452,8 +452,8 @@ static snd_pcm_fast_ops_t snd_pcm_dsnoop
>>>  	.rewind = snd_pcm_dsnoop_rewind,
>>>  	.forward = snd_pcm_dsnoop_forward,
>>>  	.resume = snd_pcm_direct_resume,
>>> -	.link_fd = NULL,
>>>  	.link = NULL,
>>> +	.link_slaves = NULL,
>>>  	.unlink = NULL,
>>>  	.writei = snd_pcm_dsnoop_writei,
>>>  	.writen = snd_pcm_dsnoop_writen,
>>> diff -r 78c78fa6c41d -r 4883f0ba21df src/pcm/pcm_file.c
>>> --- a/src/pcm/pcm_file.c	Tue Mar 13 00:40:22 2007 +0100
>>> +++ b/src/pcm/pcm_file.c	Tue Mar 13 02:52:33 2007 +0100
>>> @@ -373,8 +373,8 @@ static snd_pcm_fast_ops_t snd_pcm_file_f
>>>  	.rewind = snd_pcm_file_rewind,
>>>  	.forward = snd_pcm_file_forward,
>>>  	.resume = snd_pcm_generic_resume,
>>> -	.link_fd = snd_pcm_generic_link_fd,
>>>  	.link = snd_pcm_generic_link,
>>> +	.link_slaves = snd_pcm_generic_link_slaves,
>>>  	.unlink = snd_pcm_generic_unlink,
>>>  	.writei = snd_pcm_file_writei,
>>>  	.writen = snd_pcm_file_writen,
>>> diff -r 78c78fa6c41d -r 4883f0ba21df src/pcm/pcm_generic.c
>>> --- a/src/pcm/pcm_generic.c	Tue Mar 13 00:40:22 2007 +0100
>>> +++ b/src/pcm/pcm_generic.c	Tue Mar 13 02:52:33 2007 +0100
>>> @@ -197,14 +197,6 @@ snd_pcm_sframes_t snd_pcm_generic_rewind
>>>  	return snd_pcm_rewind(generic->slave, frames);
>>>  }
>>>  
>>> -int snd_pcm_generic_link_fd(snd_pcm_t *pcm, int *fds, int count, int (**failed)(snd_pcm_t *, int))
>>> -{
>>> -	snd_pcm_generic_t *generic = pcm->private_data;
>>> -	if (generic->slave->fast_ops->link_fd)
>>> -		return generic->slave->fast_ops->link_fd(generic->slave->fast_op_arg, fds, count, failed);
>>> -	return -ENOSYS;
>>> -}
>>> -
>>>  int snd_pcm_generic_link(snd_pcm_t *pcm1, snd_pcm_t *pcm2)
>>>  {
>>>  	snd_pcm_generic_t *generic = pcm1->private_data;
>>> @@ -213,44 +205,12 @@ int snd_pcm_generic_link(snd_pcm_t *pcm1
>>>  	return -ENOSYS;
>>>  }
>>>  
>>> -int snd_pcm_generic_link2(snd_pcm_t *pcm1, snd_pcm_t *pcm2)
>>> -{
>>> -	int fds1[16], fds2[16];
>>> -	int (*failed1)(snd_pcm_t *, int) = NULL;
>>> -	int (*failed2)(snd_pcm_t *, int) = NULL;
>>> -	int count1 = _snd_pcm_link_descriptors(pcm1, fds1, 16, &failed1);
>>> -	int count2 = _snd_pcm_link_descriptors(pcm2, fds2, 16, &failed2);
>>> -	int i, err = 0;
>>> -
>>> -	if (count1 < 0)
>>> -		return count1;
>>> -	if (count2 < 0)
>>> -		return count2;
>>> -	for (i = 1; i < count1; i++) {
>>> -		if (fds1[i] < 0)
>>> -			return 0;
>>> -		if (ioctl(fds1[0], SNDRV_PCM_IOCTL_LINK, fds1[i]) < 0) {
>>> -			if (failed1 != NULL) {
>>> -				err = failed1(pcm2, fds1[i]);
>>> -			} else {
>>> -				SYSMSG("SNDRV_PCM_IOCTL_LINK failed");
>>> -				err = -errno;
>>> -			}
>>> -		}
>>> -	}
>>> -	for (i = 0; i < count2; i++) {
>>> -		if (fds2[i] < 0)
>>> -			return 0;
>>> -		if (ioctl(fds1[0], SNDRV_PCM_IOCTL_LINK, fds2[i]) < 0) {
>>> -			if (failed1 != NULL) {
>>> -				err = failed2(pcm2, fds2[i]);
>>> -			} else {
>>> -				SYSMSG("SNDRV_PCM_IOCTL_LINK failed");
>>> -				err = -errno;
>>> -			}
>>> -		}
>>> -	}
>>> -	return err;
>>> +int snd_pcm_generic_link_slaves(snd_pcm_t *pcm, snd_pcm_t *master)
>>> +{
>>> +	snd_pcm_generic_t *generic = pcm->private_data;
>>> +	if (generic->slave->fast_ops->link_slaves)
>>> +		return generic->slave->fast_ops->link_slaves(generic->slave->fast_op_arg, master);
>>> +	return -ENOSYS;
>>>  }
>>>  
>>>  int snd_pcm_generic_unlink(snd_pcm_t *pcm)
>>> diff -r 78c78fa6c41d -r 4883f0ba21df src/pcm/pcm_generic.h
>>> --- a/src/pcm/pcm_generic.h	Tue Mar 13 00:40:22 2007 +0100
>>> +++ b/src/pcm/pcm_generic.h	Tue Mar 13 02:52:33 2007 +0100
>>> @@ -50,9 +50,8 @@ int snd_pcm_generic_delay(snd_pcm_t *pcm
>>>  int snd_pcm_generic_delay(snd_pcm_t *pcm, snd_pcm_sframes_t *delayp);
>>>  snd_pcm_sframes_t snd_pcm_generic_forward(snd_pcm_t *pcm, snd_pcm_uframes_t frames);
>>>  snd_pcm_sframes_t snd_pcm_generic_rewind(snd_pcm_t *pcm, snd_pcm_uframes_t frames);
>>> -int snd_pcm_generic_link_fd(snd_pcm_t *pcm, int *fds, int count, int (**failed)(snd_pcm_t *, int)); 
>>>  int snd_pcm_generic_link(snd_pcm_t *pcm1, snd_pcm_t *pcm2);
>>> -int snd_pcm_generic_link2(snd_pcm_t *pcm1, snd_pcm_t *pcm2);
>>> +int snd_pcm_generic_link_slaves(snd_pcm_t *pcm, snd_pcm_t *master);
>>>  int snd_pcm_generic_unlink(snd_pcm_t *pcm);
>>>  snd_pcm_sframes_t snd_pcm_generic_writei(snd_pcm_t *pcm, const void *buffer, snd_pcm_uframes_t size);
>>>  snd_pcm_sframes_t snd_pcm_generic_writen(snd_pcm_t *pcm, void **bufs, snd_pcm_uframes_t size);
>>> diff -r 78c78fa6c41d -r 4883f0ba21df src/pcm/pcm_hooks.c
>>> --- a/src/pcm/pcm_hooks.c	Tue Mar 13 00:40:22 2007 +0100
>>> +++ b/src/pcm/pcm_hooks.c	Tue Mar 13 02:52:33 2007 +0100
>>> @@ -151,8 +151,8 @@ static snd_pcm_fast_ops_t snd_pcm_hooks_
>>>  	.rewind = snd_pcm_generic_rewind,
>>>  	.forward = snd_pcm_generic_forward,
>>>  	.resume = snd_pcm_generic_resume,
>>> -	.link_fd = snd_pcm_generic_link_fd,
>>>  	.link = snd_pcm_generic_link,
>>> +	.link_slaves = snd_pcm_generic_link_slaves,
>>>  	.unlink = snd_pcm_generic_unlink,
>>>  	.writei = snd_pcm_generic_writei,
>>>  	.writen = snd_pcm_generic_writen,
>>> diff -r 78c78fa6c41d -r 4883f0ba21df src/pcm/pcm_hw.c
>>> --- a/src/pcm/pcm_hw.c	Tue Mar 13 00:40:22 2007 +0100
>>> +++ b/src/pcm/pcm_hw.c	Tue Mar 13 02:52:33 2007 +0100
>>> @@ -686,41 +686,35 @@ static int snd_pcm_hw_resume(snd_pcm_t *
>>>  	return 0;
>>>  }
>>>  
>>> -static int snd_pcm_hw_link_fd(snd_pcm_t *pcm, int *fds, int count, int (**failed)(snd_pcm_t *, int))
>>> -{
>>> -	snd_pcm_hw_t *hw = pcm->private_data;
>>> -
>>> -	if (count < 1)
>>> +static int hw_link(snd_pcm_t *pcm1, snd_pcm_t *pcm2)
>>> +{
>>> +	snd_pcm_hw_t *hw1 = pcm1->private_data;
>>> +	snd_pcm_hw_t *hw2 = pcm2->private_data;
>>> +	if (ioctl(hw1->fd, SNDRV_PCM_IOCTL_LINK, hw2->fd) < 0) {
>>> +		SYSMSG("SNDRV_PCM_IOCTL_LINK failed");
>>> +		return -errno;
>>> +	}
>>> +	return 0;
>>> +}
>>> +
>>> +static int snd_pcm_hw_link_slaves(snd_pcm_t *pcm, snd_pcm_t *master)
>>> +{
>>> +	if (master->type != SND_PCM_TYPE_HW) {
>>> +		SYSMSG("Invalid type for SNDRV_PCM_IOCTL_LINK");
>>>  		return -EINVAL;
>>> -	*failed = NULL;
>>> -	fds[0] = hw->fd;
>>> -	return 1;
>>> +	}
>>> +	return hw_link(master, pcm);
>>>  }
>>>  
>>>  static int snd_pcm_hw_link(snd_pcm_t *pcm1, snd_pcm_t *pcm2)
>>>  {
>>> -	snd_pcm_hw_t *hw = pcm1->private_data;
>>> -	int fds[16];
>>> -	int (*failed)(snd_pcm_t *, int) = NULL;
>>> -	int count = _snd_pcm_link_descriptors(pcm2, fds, 16, &failed);
>>> -	int i, err = 0;
>>> -
>>> -	if (count < 0)
>>> -		return count;
>>> -	for (i = 0; i < count; i++) {
>>> -		if (fds[i] < 0)
>>> -			return 0;
>>> -		if (ioctl(hw->fd, SNDRV_PCM_IOCTL_LINK, fds[i]) < 0) {
>>> -			if (failed != NULL) {
>>> -				err = failed(pcm2, fds[i]);
>>> -			} else {
>>> -				SYSMSG("SNDRV_PCM_IOCTL_LINK failed");
>>> -				err = -errno;
>>> -			}
>>> -		}
>>> -	}
>>> -	return err;
>>> -}
>>> +	if (pcm2->type != SND_PCM_TYPE_HW) {
>>> +		if (pcm2->fast_ops->link_slaves)
>>> +			return pcm2->fast_ops->link_slaves(pcm2, pcm1);
>>> +		return -ENOSYS;
>>> +	}
>>> +	return hw_link(pcm1, pcm2);
>>> + }
>>>  
>>>  static int snd_pcm_hw_unlink(snd_pcm_t *pcm)
>>>  {
>>> @@ -1045,8 +1039,8 @@ static snd_pcm_fast_ops_t snd_pcm_hw_fas
>>>  	.rewind = snd_pcm_hw_rewind,
>>>  	.forward = snd_pcm_hw_forward,
>>>  	.resume = snd_pcm_hw_resume,
>>> -	.link_fd = snd_pcm_hw_link_fd,
>>>  	.link = snd_pcm_hw_link,
>>> +	.link_slaves = snd_pcm_hw_link_slaves,
>>>  	.unlink = snd_pcm_hw_unlink,
>>>  	.writei = snd_pcm_hw_writei,
>>>  	.writen = snd_pcm_hw_writen,
>>> diff -r 78c78fa6c41d -r 4883f0ba21df src/pcm/pcm_ioplug.c
>>> --- a/src/pcm/pcm_ioplug.c	Tue Mar 13 00:40:22 2007 +0100
>>> +++ b/src/pcm/pcm_ioplug.c	Tue Mar 13 02:52:33 2007 +0100
>>> @@ -747,8 +747,8 @@ static snd_pcm_fast_ops_t snd_pcm_ioplug
>>>  	.hwsync = snd_pcm_ioplug_hwsync,
>>>  	.delay = snd_pcm_ioplug_delay,
>>>  	.resume = snd_pcm_ioplug_resume,
>>> -	.link_fd = NULL,
>>>  	.link = NULL,
>>> +	.link_slaves = NULL,
>>>  	.unlink = NULL,
>>>  	.rewind = snd_pcm_ioplug_rewind,
>>>  	.forward = snd_pcm_ioplug_forward,
>>> diff -r 78c78fa6c41d -r 4883f0ba21df src/pcm/pcm_local.h
>>> --- a/src/pcm/pcm_local.h	Tue Mar 13 00:40:22 2007 +0100
>>> +++ b/src/pcm/pcm_local.h	Tue Mar 13 02:52:33 2007 +0100
>>> @@ -152,8 +152,8 @@ typedef struct {
>>>  	int (*hwsync)(snd_pcm_t *pcm);
>>>  	int (*delay)(snd_pcm_t *pcm, snd_pcm_sframes_t *delayp);
>>>  	int (*resume)(snd_pcm_t *pcm);
>>> -	int (*link_fd)(snd_pcm_t *pcm, int *fds, int count, int (**failed)(snd_pcm_t *, int));
>>>  	int (*link)(snd_pcm_t *pcm1, snd_pcm_t *pcm2);
>>> +	int (*link_slaves)(snd_pcm_t *pcm, snd_pcm_t *master);
>>>  	int (*unlink)(snd_pcm_t *pcm);
>>>  	snd_pcm_sframes_t (*rewind)(snd_pcm_t *pcm, snd_pcm_uframes_t frames);
>>>  	snd_pcm_sframes_t (*forward)(snd_pcm_t *pcm, snd_pcm_uframes_t frames);
>>> diff -r 78c78fa6c41d -r 4883f0ba21df src/pcm/pcm_multi.c
>>> --- a/src/pcm/pcm_multi.c	Tue Mar 13 00:40:22 2007 +0100
>>> +++ b/src/pcm/pcm_multi.c	Tue Mar 13 02:52:33 2007 +0100
>>> @@ -45,7 +45,7 @@ typedef struct {
>>>  	snd_pcm_t *pcm;
>>>  	unsigned int channels_count;
>>>  	int close_slave;
>>> -	int linked;
>>> +	snd_pcm_t *linked;
>>>  } snd_pcm_multi_slave_t;
>>>  
>>>  typedef struct {
>>> @@ -57,7 +57,6 @@ typedef struct {
>>>  	unsigned int slaves_count;
>>>  	unsigned int master_slave;
>>>  	snd_pcm_multi_slave_t *slaves;
>>> -	int slave_link_master;
>>>  	unsigned int channels_count;
>>>  	snd_pcm_multi_channel_t *channels;
>>>  } snd_pcm_multi_t;
>>> @@ -314,6 +313,21 @@ static int snd_pcm_multi_hw_params_slave
>>>  	return 0;
>>>  }
>>>  
>>> +static void reset_links(snd_pcm_multi_t *multi)
>>> +{
>>> +	unsigned int i;
>>> +
>>> +	for (i = 0; i < multi->slaves_count; ++i) {
>>> +		if (multi->slaves[i].linked)
>>> +			snd_pcm_unlink(multi->slaves[i].linked);
>>> +		multi->slaves[0].linked = NULL;
>>> +		if (! i)
>>> +			continue;
>>> +		if (snd_pcm_link(multi->slaves[0].pcm, multi->slaves[i].pcm) >= 0)
>>> +			multi->slaves[i].linked = multi->slaves[0].pcm;
>>> +	}
>>> +}
>>> +
>>>  static int snd_pcm_multi_hw_params(snd_pcm_t *pcm, snd_pcm_hw_params_t *params)
>>>  {
>>>  	snd_pcm_multi_t *multi = pcm->private_data;
>>> @@ -331,12 +345,7 @@ static int snd_pcm_multi_hw_params(snd_p
>>>  			return err;
>>>  		}
>>>  	}
>>> -	multi->slaves[0].linked = 0;
>>> -	multi->slave_link_master = 0;
>>> -	for (i = 1; i < multi->slaves_count; ++i) {
>>> -		err = snd_pcm_link(multi->slaves[0].pcm, multi->slaves[i].pcm);
>>> -		multi->slaves[i].linked = (err >= 0);
>>> -	}
>>> +	reset_links(multi);
>>>  	return 0;
>>>  }
>>>  
>>> @@ -352,10 +361,10 @@ static int snd_pcm_multi_hw_free(snd_pcm
>>>  			err = e;
>>>  		if (!multi->slaves[i].linked)
>>>  			continue;
>>> -		multi->slaves[i].linked = 0;
>>>  		e = snd_pcm_unlink(slave);
>>>  		if (e < 0)
>>>  			err = e;
>>> +		multi->slaves[i].linked = NULL;
>>>  	}
>>>  	return err;
>>>  }
>>> @@ -421,7 +430,7 @@ static int snd_pcm_multi_prepare(snd_pcm
>>>  static int snd_pcm_multi_prepare(snd_pcm_t *pcm)
>>>  {
>>>  	snd_pcm_multi_t *multi = pcm->private_data;
>>> -	int err = 0;
>>> +	int result = 0, err;
>>>  	unsigned int i;
>>>  	for (i = 0; i < multi->slaves_count; ++i) {
>>>  		/* We call prepare to each slave even if it's linked.
>>> @@ -429,75 +438,83 @@ static int snd_pcm_multi_prepare(snd_pcm
>>>  		 */
>>>  		err = snd_pcm_prepare(multi->slaves[i].pcm);
>>>  		if (err < 0)
>>> -			return err;
>>> -	}
>>> -	return err;
>>> +			result = err;
>>> +	}
>>> +	return result;
>>>  }
>>>  
>>>  static int snd_pcm_multi_reset(snd_pcm_t *pcm)
>>>  {
>>>  	snd_pcm_multi_t *multi = pcm->private_data;
>>> -	int err = 0;
>>> +	int result = 0, err;
>>>  	unsigned int i;
>>>  	for (i = 0; i < multi->slaves_count; ++i) {
>>>  		/* Reset each slave, as well as in prepare */
>>>  		err = snd_pcm_reset(multi->slaves[i].pcm);
>>> +		if (err < 0) 
>>> +			result = err;
>>> +	}
>>> +	return result;
>>> +}
>>> +
>>> +static int snd_pcm_multi_start(snd_pcm_t *pcm)
>>> +{
>>> +	snd_pcm_multi_t *multi = pcm->private_data;
>>> +	int err = 0;
>>> +	unsigned int i;
>>> +	if (multi->slaves[0].linked)
>>> +		return snd_pcm_start(multi->slaves[0].linked);
>>> +	for (i = 0; i < multi->slaves_count; ++i) {
>>> +		if (multi->slaves[i].linked)
>>> +			continue;
>>> +		err = snd_pcm_start(multi->slaves[i].pcm);
>>>  		if (err < 0)
>>>  			return err;
>>>  	}
>>>  	return err;
>>>  }
>>>  
>>> -static int snd_pcm_multi_start(snd_pcm_t *pcm)
>>> +static int snd_pcm_multi_drop(snd_pcm_t *pcm)
>>>  {
>>>  	snd_pcm_multi_t *multi = pcm->private_data;
>>>  	int err = 0;
>>>  	unsigned int i;
>>> +	if (multi->slaves[0].linked)
>>> +		return snd_pcm_drop(multi->slaves[0].linked);
>>>  	for (i = 0; i < multi->slaves_count; ++i) {
>>>  		if (multi->slaves[i].linked)
>>>  			continue;
>>> -		err = snd_pcm_start(multi->slaves[i].pcm);
>>> +		err = snd_pcm_drop(multi->slaves[i].pcm);
>>>  		if (err < 0)
>>>  			return err;
>>>  	}
>>>  	return err;
>>>  }
>>>  
>>> -static int snd_pcm_multi_drop(snd_pcm_t *pcm)
>>> +static int snd_pcm_multi_drain(snd_pcm_t *pcm)
>>>  {
>>>  	snd_pcm_multi_t *multi = pcm->private_data;
>>>  	int err = 0;
>>>  	unsigned int i;
>>> +	if (multi->slaves[0].linked)
>>> +		return snd_pcm_drain(multi->slaves[0].linked);
>>>  	for (i = 0; i < multi->slaves_count; ++i) {
>>>  		if (multi->slaves[i].linked)
>>>  			continue;
>>> -		err = snd_pcm_drop(multi->slaves[i].pcm);
>>> +		err = snd_pcm_drain(multi->slaves[i].pcm);
>>>  		if (err < 0)
>>>  			return err;
>>>  	}
>>>  	return err;
>>>  }
>>>  
>>> -static int snd_pcm_multi_drain(snd_pcm_t *pcm)
>>> +static int snd_pcm_multi_pause(snd_pcm_t *pcm, int enable)
>>>  {
>>>  	snd_pcm_multi_t *multi = pcm->private_data;
>>>  	int err = 0;
>>>  	unsigned int i;
>>> -	for (i = 0; i < multi->slaves_count; ++i) {
>>> -		if (multi->slaves[i].linked)
>>> -			continue;
>>> -		err = snd_pcm_drain(multi->slaves[i].pcm);
>>> -		if (err < 0)
>>> -			return err;
>>> -	}
>>> -	return err;
>>> -}
>>> -
>>> -static int snd_pcm_multi_pause(snd_pcm_t *pcm, int enable)
>>> -{
>>> -	snd_pcm_multi_t *multi = pcm->private_data;
>>> -	int err = 0;
>>> -	unsigned int i;
>>> +	if (multi->slaves[0].linked)
>>> +		return snd_pcm_pause(multi->slaves[0].linked, enable);
>>>  	for (i = 0; i < multi->slaves_count; ++i) {
>>>  		if (multi->slaves[i].linked)
>>>  			continue;
>>> @@ -587,6 +604,8 @@ static int snd_pcm_multi_resume(snd_pcm_
>>>  	snd_pcm_multi_t *multi = pcm->private_data;
>>>  	int err = 0;
>>>  	unsigned int i;
>>> +	if (multi->slaves[0].linked)
>>> +		return snd_pcm_resume(multi->slaves[0].linked);
>>>  	for (i = 0; i < multi->slaves_count; ++i) {
>>>  		if (multi->slaves[i].linked)
>>>  			continue;
>>> @@ -597,46 +616,42 @@ static int snd_pcm_multi_resume(snd_pcm_
>>>  	return err;
>>>  }
>>>  
>>> -static int snd_pcm_multi_link_fd_failed(snd_pcm_t *pcm, int fd)
>>> -{
>>> -	snd_pcm_multi_t *multi = pcm->private_data;
>>> -	unsigned int i;
>>> -
>>> -	for (i = 0; i < multi->slaves_count; ++i) {
>>> -		if (_snd_pcm_link_descriptor(multi->slaves[i].pcm) != fd)
>>> -			continue;
>>> -		 multi->slaves[i].linked = 0;
>>> -	}
>>> -	return 0;
>>> -}
>>> -
>>> -static int snd_pcm_multi_link_fd(snd_pcm_t *pcm, int *fds, int count, int (**failed)(snd_pcm_t *pcm, int fd))
>>> +static int snd_pcm_multi_link_slaves(snd_pcm_t *pcm, snd_pcm_t *master)
>>>  { 
>>>  	snd_pcm_multi_t *multi = pcm->private_data;
>>> -	unsigned int i;
>>> -
>>> -	if (count < (int)multi->slaves_count)
>>> -		return -ENOMEM;
>>> +	unsigned int i, j;
>>> +	int err;
>>> +
>>> +	for (i = 0; i < multi->slaves_count; ++i) {
>>> +		snd_pcm_unlink(multi->slaves[i].pcm);
>>> +		multi->slaves[i].linked = NULL;
>>> +		err = snd_pcm_link(master, multi->slaves[i].pcm);
>>> +		if (err < 0) {
>>> +			reset_links(multi);
>>> +			return err;
>>> +		}
>>> +		multi->slaves[i].linked = master;
>>> +	}
>>> +	return 0;
>>> +}
>>> +
>>> +static int snd_pcm_multi_link(snd_pcm_t *pcm1, snd_pcm_t *pcm2)
>>> +{
>>> +	snd_pcm_multi_t *multi = pcm1->private_data;
>>> +	if (multi->slaves[0].pcm->fast_ops->link)
>>> +		return multi->slaves[0].pcm->fast_ops->link(multi->slaves[0].pcm, pcm2);
>>> +	return -ENOSYS;
>>> +}
>>> +
>>> +static int snd_pcm_multi_unlink(snd_pcm_t *pcm)
>>> +{
>>> +	snd_pcm_multi_t *multi = pcm->private_data;
>>> +	unsigned int i;
>>> +
>>>  	for (i = 0; i < multi->slaves_count; ++i) {
>>>  		if (multi->slaves[i].linked)
>>> -			snd_pcm_unlink(multi->slaves[i].pcm);
>>> -		fds[i] = _snd_pcm_link_descriptor(multi->slaves[i].pcm);
>>> -		if (i > 0)
>>> -			multi->slaves[i].linked = 1;
>>> -	}
>>> -	*failed = snd_pcm_multi_link_fd_failed;
>>> -	return multi->slaves_count;
>>> -}
>>> -
>>> -static int snd_pcm_multi_unlink(snd_pcm_t *pcm)
>>> -{
>>> -	snd_pcm_multi_t *multi = pcm->private_data;
>>> -	unsigned int i;
>>> -
>>> -	for (i = 0; i < multi->slaves_count; ++i) {
>>> -		if (multi->slaves[i].linked)
>>> -			snd_pcm_unlink(multi->slaves[i].pcm);
>>> -		multi->slaves[i].linked = 0;
>>> +			snd_pcm_unlink(multi->slaves[i].linked);
>>> +		multi->slaves[0].linked = NULL;
>>>  	}
>>>  	return 0;
>>>  }
>>> @@ -727,8 +742,8 @@ static snd_pcm_fast_ops_t snd_pcm_multi_
>>>  	.rewind = snd_pcm_multi_rewind,
>>>  	.forward = snd_pcm_multi_forward,
>>>  	.resume = snd_pcm_multi_resume,
>>> -	.link_fd = snd_pcm_multi_link_fd,
>>> -	.link = snd_pcm_generic_link2,
>>> +	.link = snd_pcm_multi_link,
>>> +	.link_slaves = snd_pcm_multi_link_slaves,
>>>  	.unlink = snd_pcm_multi_unlink,
>>>  	.avail_update = snd_pcm_multi_avail_update,
>>>  	.mmap_commit = snd_pcm_multi_mmap_commit,
>>> diff -r 78c78fa6c41d -r 4883f0ba21df src/pcm/pcm_plugin.c
>>> --- a/src/pcm/pcm_plugin.c	Tue Mar 13 00:40:22 2007 +0100
>>> +++ b/src/pcm/pcm_plugin.c	Tue Mar 13 02:52:33 2007 +0100
>>> @@ -566,8 +566,8 @@ snd_pcm_fast_ops_t snd_pcm_plugin_fast_o
>>>  	.rewind = snd_pcm_plugin_rewind,
>>>  	.forward = snd_pcm_plugin_forward,
>>>  	.resume = snd_pcm_generic_resume,
>>> -	.link_fd = snd_pcm_generic_link_fd,
>>>  	.link = snd_pcm_generic_link,
>>> +	.link_slaves = snd_pcm_generic_link_slaves,
>>>  	.unlink = snd_pcm_generic_unlink,
>>>  	.writei = snd_pcm_plugin_writei,
>>>  	.writen = snd_pcm_plugin_writen,
>>>
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>>>
>>>
>>>   
>>>       
>
>
>   


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