[alsa-devel] Timer interface
Hi,
I am extending my ALSA driver in order to support software mixing. Driver currently supports both MMAP and RW access modes. However, I am still not able to use dmix since it requires timer interface to be implemented. My hardware does not generate interrupts at the period boundary but issues timer interrupts at a fixed timer rate.
Could you please point me to the document or sample driver that can help me to fully understand timer interface concept (especially for High frequency timer interrupts)?
Thanks, Nenad
At Fri, 29 Jul 2011 17:05:23 +0200, Nenad Sljivic wrote:
Hi,
I am extending my ALSA driver in order to support software mixing. Driver currently supports both MMAP and RW access modes. However, I am still not able to use dmix since it requires timer interface to be implemented. My hardware does not generate interrupts at the period boundary but issues timer interrupts at a fixed timer rate.
The timer interface is always present with ALSA (kernel) PCM interface, thus normally you don't have to implement it. Or are you trying to implement without the normal kernel driver but with alsa-lib ioplug or such?
Takashi
Takashi,
Thanks for your help. My timer device has not been created at the correct path (/dev/snd), so I thought it was missing and that I need to implement it.
-----Original Message----- From: Takashi Iwai [mailto:tiwai@suse.de] Sent: 02 August 2011 07:54 To: Nenad Sljivic Cc: alsa-devel@alsa-project.org Subject: Re: [alsa-devel] Timer interface
At Fri, 29 Jul 2011 17:05:23 +0200, Nenad Sljivic wrote:
Hi,
I am extending my ALSA driver in order to support software mixing. Driver currently supports both MMAP and RW access modes. However, I am still not able to use dmix since it requires timer interface to be implemented. My hardware does not generate interrupts at the period boundary but issues timer interrupts at a fixed timer rate.
The timer interface is always present with ALSA (kernel) PCM interface, thus normally you don't have to implement it. Or are you trying to implement without the normal kernel driver but with alsa-lib ioplug or such?
Takashi
At Tue, 2 Aug 2011 12:33:32 +0200, Nenad Sljivic wrote:
Takashi,
Thanks for your help. My timer device has not been created at the correct path (/dev/snd), so I thought it was missing and that I need to implement it.
No, you don't have to implement the timer in your driver explicitly. A slave-timer instance is created for each PCM stream (see sound/core/pcm_timer.c), and dmix uses this. Look at /proc/asound/timers. On my machine, it shows like:
G0: system timer : 4000.000us (10000000 ticks) P0-0-0: PCM playback 0-0-0 : SLAVE P0-0-1: PCM capture 0-0-1 : SLAVE P0-2-1: PCM capture 0-2-1 : SLAVE P0-2-3: PCM capture 0-2-3 : SLAVE P1-3-0: PCM playback 1-3-0 : SLAV
Takashi
-----Original Message----- From: Takashi Iwai [mailto:tiwai@suse.de] Sent: 02 August 2011 07:54 To: Nenad Sljivic Cc: alsa-devel@alsa-project.org Subject: Re: [alsa-devel] Timer interface
At Fri, 29 Jul 2011 17:05:23 +0200, Nenad Sljivic wrote:
Hi,
I am extending my ALSA driver in order to support software mixing. Driver currently supports both MMAP and RW access modes. However, I am still not able to use dmix since it requires timer interface to be implemented. My hardware does not generate interrupts at the period boundary but issues timer interrupts at a fixed timer rate.
The timer interface is always present with ALSA (kernel) PCM interface, thus normally you don't have to implement it. Or are you trying to implement without the normal kernel driver but with alsa-lib ioplug or such?
Takashi
Alsa-devel mailing list Alsa-devel@alsa-project.org http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
Hi,
I got it. I've fixed the problem with the node creation and dmix works fine now. Thanks
-----Original Message----- From: Takashi Iwai [mailto:tiwai@suse.de] Sent: 02 August 2011 12:37 To: Nenad Sljivic Cc: alsa-devel@alsa-project.org Subject: Re: [alsa-devel] Timer interface
At Tue, 2 Aug 2011 12:33:32 +0200, Nenad Sljivic wrote:
Takashi,
Thanks for your help. My timer device has not been created at the correct path (/dev/snd), so I thought it was missing and that I need to implement it.
No, you don't have to implement the timer in your driver explicitly. A slave-timer instance is created for each PCM stream (see sound/core/pcm_timer.c), and dmix uses this. Look at /proc/asound/timers. On my machine, it shows like:
G0: system timer : 4000.000us (10000000 ticks) P0-0-0: PCM playback 0-0-0 : SLAVE P0-0-1: PCM capture 0-0-1 : SLAVE P0-2-1: PCM capture 0-2-1 : SLAVE P0-2-3: PCM capture 0-2-3 : SLAVE P1-3-0: PCM playback 1-3-0 : SLAV
Takashi
-----Original Message----- From: Takashi Iwai [mailto:tiwai@suse.de] Sent: 02 August 2011 07:54 To: Nenad Sljivic Cc: alsa-devel@alsa-project.org Subject: Re: [alsa-devel] Timer interface
At Fri, 29 Jul 2011 17:05:23 +0200, Nenad Sljivic wrote:
Hi,
I am extending my ALSA driver in order to support software mixing.
Driver
currently supports both MMAP and RW access modes. However, I am still
not
able to use dmix since it requires timer interface to be implemented. My hardware does not generate interrupts at the period boundary but
issues
timer interrupts at a fixed timer rate.
The timer interface is always present with ALSA (kernel) PCM interface, thus normally you don't have to implement it. Or are you trying to implement without the normal kernel driver but with alsa-lib ioplug or such?
Takashi
Alsa-devel mailing list Alsa-devel@alsa-project.org http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
participants (2)
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Nenad Sljivic -
Takashi Iwai