mirror of
https://github.com/torvalds/linux.git
synced 2024-11-28 23:21:31 +00:00
dec63cc8b6
In clause 6.3 of IEC 61883-6:2000, there's an explanation about processing of presentation timestamp. In the clause, we can see "If a function block receives a CIP, processes it and subsequently re-transmits it, then the SYT of the outgoing CIP shall be the sum of the incoming SYT and the processing delay." ALSA firewire stack has an implementation to partly satisfy this specification. Developers assumed the stack to perform as an Audio function block[1]. Following to the assumption, current implementation of ALSA firewire stack use one software interrupt context to handle both of in/out packets. In most case, this is processed in 1394 OHCI IR context independently of the opposite context. Thus, this implementation uses longer CPU time in the software interrupt context. This is not better for whole system. Against the assumption, I confirmed that each ASIC for IEC 61883-1/6 doesn't necessarily expect it to the stack. Thus, current implementation of ALSA firewire stack includes over-engineering. This commit purges the implementation. As a result, packets of one direction are handled in one software interrupt context and spends minimum CPU time. [1] [alsa-devel] [PATCH 0/8] [RFC] new driver for Echo Audio's Fireworks based devices http://mailman.alsa-project.org/pipermail/alsa-devel/2013-June/062660.html Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp> Signed-off-by: Takashi Iwai <tiwai@suse.de> |
||
|---|---|---|
| .. | ||
| aoa | ||
| arm | ||
| atmel | ||
| core | ||
| drivers | ||
| firewire | ||
| hda | ||
| i2c | ||
| isa | ||
| mips | ||
| oss | ||
| parisc | ||
| pci | ||
| pcmcia | ||
| ppc | ||
| sh | ||
| soc | ||
| sparc | ||
| spi | ||
| synth | ||
| usb | ||
| ac97_bus.c | ||
| Kconfig | ||
| last.c | ||
| Makefile | ||
| sound_core.c | ||
| sound_firmware.c | ||