[LAD] Usb Audio Driver
Hello LAD, I'm working in company which is developing a guitar pedal board which runs Linux (arch) and my task now is to make the kernel's usb audio driver more appropriate to our sound card. I'm kinda lost in this since i have a brief knowledge on usb protocol so I was hoping that you could give me some directions on how can I optimize the driver latency wise, any tips? Att, Lucas ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Usb Audio Driver
On Wed, December 11, 2013 7:44 am, Lucas Takejame wrote: > Hello LAD, I'm working in company which is developing a guitar pedal board > which runs Linux (arch) and my task now is to make the kernel's usb audio > driver more appropriate to our sound card. I'm kinda lost in this since i > have a brief knowledge on usb protocol so I was hoping that you could give > me some directions on how can I optimize the driver latency wise, any > tips? > The ALSA USB Audio driver is already highly optimised. If you are seeing specific issues the alsa-devel mailing list is a better place to discuss. Or are you looking to optimise the kernel and operating system? FYI, other LADers have been using usb devices with 64 frames per period which provides less than 2ms round trip latency. -- Patrick Shirkey Boost Hardware Ltd ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Usb Audio Driver
On 12/10/2013 12:44 PM, Lucas Takejame wrote: Hello LAD, I'm working in company which is developing a guitar pedal board which runs Linux (arch) and my task now is to make the kernel's usb audio driver more appropriate to our sound card. I'm kinda lost in this since i have a brief knowledge on usb protocol so I was hoping that you could give me some directions on how can I optimize the driver latency wise, any tips? There's several folks here who do this, but your best bet is to look for advice (or contractors) on the alsa-devel mailing list.[1] One option is to implement a class-compliant USB Audio device. Then your device will work out of the box with all operating systems. If class-compliance doesn't suit your device... then look for examples in the linux kernel in sound/usb where there's a few non-class-compliant cards cards supported there. In addition, check out these resources: * Takashi Iwei's ALSA driver tutorial[2]. Concentrate on the PCM interface portion of the document. * Linux Device Drivers from O'Reilly media.[3] -gabe [1] http://mailman.alsa-project.org/mailman/listinfo/alsa-devel [2] http://www.alsa-project.org/~tiwai/writing-an-alsa-driver/ [3] http://lwn.net/Kernel/LDD3/ ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Usb Audio Driver
Lucas Takejame wrote: > my task now is to make the kernel's usb audio driver more appropriate > to our sound card. What specific problem do you have? > I was hoping that you could give me some directions on how can I > optimize the driver latency wise, any tips? For playback, you get lower latency by using a smaller buffer (which also increases the chance of an underrun). Regards, Clemens ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Usb Audio Driver
We are already using a RT-kernel and I guess we already did everything we could do on OS changes to achieve a better latency. My doubt is if I can change anything on the snd-usb driver to make it specific to our sound card, aiming an improve in latency, since our pedalboard ( http://portalmod.com/en/index.html) has this sound card fixed and we won't need a generic driver to the usb connection. I'm gonna send an e-mail to the alsa-devel ML, thanks for the advices! 2013/12/11 Clemens Ladisch > Lucas Takejame wrote: > > my task now is to make the kernel's usb audio driver more appropriate > > to our sound card. > > What specific problem do you have? > > > I was hoping that you could give me some directions on how can I > > optimize the driver latency wise, any tips? > > For playback, you get lower latency by using a smaller buffer (which > also increases the chance of an underrun). > > > Regards, > Clemens > ___ > Linux-audio-dev mailing list > Linux-audio-dev@lists.linuxaudio.org > http://lists.linuxaudio.org/listinfo/linux-audio-dev > -- Lucas Conejero Takejame Engenharia Elétrica - ênfase em computação Escola Politécnica - USP ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Usb Audio Driver
On Wed, 2013-12-11 at 14:31 -0200, Lucas Takejame wrote: > We are already using a RT-kernel and I guess we already did everything > we could do on OS changes to achieve a better latency. My doubt is if > I can change anything on the snd-usb driver to make it specific to our > sound card, aiming an improve in latency, since our pedalboard > (http://portalmod.com/en/index.html) has this sound card fixed and we > won't need a generic driver to the usb connection. I'm gonna send an > e-mail to the alsa-devel ML, thanks for the advices! Linux audio user might be a better place to ask first. Since you're using Arch, ArchAudio mailing list might be a good place too. Get rid of as much as you can and avoid shared IRQs. If I only need my RME card, sometimes I even disable the Envy24 MIDI interfaces. Often I don't use this script, because it doesn't really improve issues that much on my machine, but you never know and could try as much tuning as possible. Perhaps the links are still helpful, I don't know. [rocketmouse@archlinux ~]$ cat /usr/local/sbin/tuning #!/bin/bash # /usr/local/sbin/tuning - Arch Linux # 2013/Apr/05 ### http://www.mythtv.org/wiki/PCI_Latency ### http://wiki.linuxmusicians.com/doku.php?id=system_configuration#pci_bus_latency ### Bluetooth #service bluetooth stop ### Network #service network-manager stop #service networking stop # does cause serious issues #modprobe -r r8169 # Ethernet NIC driver ### TerraTec EWX 24/96 #modprobe -r snd_ice1712 ### Others modprobe -r firewire-ohci modprobe -r firewire_core #service cups stop modprobe -r ppdev # parallel port modprobe -r lp# printer ### Unbinding devices echo -n ":00:13.2" > /sys/bus/pci/drivers/ohci_hcd/unbind echo -n ":00:13.4" > /sys/bus/pci/drivers/ohci_hcd/unbind ### Log file l="/var/log/tuning.log" #echo "$ lspci -v " > $l #lspci -v >> $l #echo >> $l echo "# service rtirq status " > $l service rtirq status >> $l echo "# grep 18: /proc/interrupts" >> $l grep 18: /proc/interrupts>> $l echo >> $l echo -n $(date)" - "$(uname -r)" - " >> $l cat /etc/issue >> $l echo -e "\n\n" ; cat $l exit 0 ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Usb Audio Driver
Thanks for your response Ralf, our Arch is pretty much dedicated to audio already, we maintained only the necessary to work as a LV2 host (this script wouldn't do much actually) and the IRQ's are not shared, we are using different USB hubs to prioritize audio, I think we did what we could without changing code lines already, this is why I was asking about the drivers haha. 2013/12/11 Ralf Mardorf > On Wed, 2013-12-11 at 14:31 -0200, Lucas Takejame wrote: > > We are already using a RT-kernel and I guess we already did everything > > we could do on OS changes to achieve a better latency. My doubt is if > > I can change anything on the snd-usb driver to make it specific to our > > sound card, aiming an improve in latency, since our pedalboard > > (http://portalmod.com/en/index.html) has this sound card fixed and we > > won't need a generic driver to the usb connection. I'm gonna send an > > e-mail to the alsa-devel ML, thanks for the advices! > > > Linux audio user might be a better place to ask first. Since you're > using Arch, ArchAudio mailing list might be a good place too. > > Get rid of as much as you can and avoid shared IRQs. If I only need my > RME card, sometimes I even disable the Envy24 MIDI interfaces. > > Often I don't use this script, because it doesn't really improve issues > that much on my machine, but you never know and could try as much tuning > as possible. > > Perhaps the links are still helpful, I don't know. > > [rocketmouse@archlinux ~]$ cat /usr/local/sbin/tuning > #!/bin/bash > > # /usr/local/sbin/tuning - Arch Linux > # 2013/Apr/05 > > ### http://www.mythtv.org/wiki/PCI_Latency > ### > http://wiki.linuxmusicians.com/doku.php?id=system_configuration#pci_bus_latency > > ### Bluetooth > #service bluetooth stop > > ### Network > #service network-manager stop > #service networking stop # does cause serious issues > #modprobe -r r8169 # Ethernet NIC driver > > ### TerraTec EWX 24/96 > #modprobe -r snd_ice1712 > > ### Others > modprobe -r firewire-ohci > modprobe -r firewire_core > #service cups stop > modprobe -r ppdev # parallel port > modprobe -r lp# printer > > ### Unbinding devices > echo -n ":00:13.2" > /sys/bus/pci/drivers/ohci_hcd/unbind > echo -n ":00:13.4" > /sys/bus/pci/drivers/ohci_hcd/unbind > > ### Log file > l="/var/log/tuning.log" > #echo "$ lspci -v " > $l > #lspci -v >> $l > #echo >> $l > echo "# service rtirq status " > $l > service rtirq status >> $l > echo "# grep 18: /proc/interrupts" >> $l > grep 18: /proc/interrupts>> $l > echo >> $l > echo -n $(date)" - "$(uname -r)" - " >> $l > cat /etc/issue >> $l > echo -e > "\n\n" > ; cat $l > > exit 0 > > > ___ > Linux-audio-dev mailing list > Linux-audio-dev@lists.linuxaudio.org > http://lists.linuxaudio.org/listinfo/linux-audio-dev > -- Lucas Conejero Takejame Engenharia Elétrica - ênfase em computação Escola Politécnica - USP ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Usb Audio Driver
On Wed, 2013-12-11 at 17:00 -0200, Lucas Takejame wrote: > Thanks for your response Ralf, our Arch is pretty much dedicated to > audio already, we maintained only the necessary to work as a LV2 host > (this script wouldn't do much actually) and the IRQ's are not shared, > we are using different USB hubs to prioritize audio, I think we did > what we could without changing code lines already, this is why I was > asking about the drivers haha. Sure, the script is for my machine, I only wanted to point out, that I would test what happens if everything that is unneeded is removed. To check if rtirq is ok, since after a linux-rt upgrade it could be broken, but if you already cared about such things, I suspect there is nothing you can do. ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Usb Audio Driver
Me too 2013/12/11 Ralf Mardorf > On Wed, 2013-12-11 at 17:00 -0200, Lucas Takejame wrote: > > Thanks for your response Ralf, our Arch is pretty much dedicated to > > audio already, we maintained only the necessary to work as a LV2 host > > (this script wouldn't do much actually) and the IRQ's are not shared, > > we are using different USB hubs to prioritize audio, I think we did > > what we could without changing code lines already, this is why I was > > asking about the drivers haha. > > Sure, the script is for my machine, I only wanted to point out, that I > would test what happens if everything that is unneeded is removed. To > check if rtirq is ok, since after a linux-rt upgrade it could be broken, > but if you already cared about such things, I suspect there is nothing > you can do. > > > -- Lucas Conejero Takejame Engenharia Elétrica - ênfase em computação Escola Politécnica - USP ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Usb Audio Driver
Hi Lucas, What are the problems that the supposed driver modification is meant to solve? Ciao, Kaspar ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
