Takashi Iwai wrote: > At Sat, 03 May 2008 21:12:02 +0200, > Pavel Hofman wrote: >> >> >> Takashi Iwai wrote: >>> At Wed, 30 Apr 2008 22:07:42 +0200, >>> Pavel Hofman wrote: >>>> Takashi Iwai wrote: >>>>> At Fri, 25 Apr 2008 09:06:19 +0200, >>>>> Pavel Hofman wrote: >>>> The code works fine on standard kernel. >>>> >>>> But in the RT kernel of Ubuntu 7.10 (2.6.22-14-rt, 1000HZ compared to >>>> 250HZ of the -generic kernel), MIDI interrupts get thrown continuously, >>>> hogging CPU with the IRQXX "process". >>>> >>>> When playing 44.1kHz audio with buffer size of 32768, >>>> snd_vt1724_interrupt is called every 185ms. With the buffer size of >>>> 4096, it is every 23ms. So far so good. >>>> >>>> But when I try to output some midi, the routine gets called every 24us >>>> (i.e. 1000 times faster). Comparing the time difference between my >>>> several debug printk's in snd_vt1724_interrupt (approx. 5us between each >>>> printk record a few lines of code apart) and between each call of the >>>> method (24us), I thought there would be a loop somewhere in the >>>> interrupt handler calling code. But /proc/interrupts really shows over >>>> 40k interrupts a second for ICE1724. >>>> >>>> Changing the watermarks up to 0x1f makes no difference. >>> That looks bad. >>> >>>> Masking the MIDI interrupts works, snd_vt1724_interrupt is called only >>>> during VT1724_IRQ_MTPCM interrupts, with the MIDI status bits >>>> MPU_TX/MPU_RX set when reading/writing with amidi. >>> Hm, is it TX or RX, or in both cases? >>> Could you check which one (TX or RX) causes this? >>> >> Both reading (amidi -p hw:0 -d) and writing (amidi -p hw:0 -S >> F0411042110C000000000074FF0411042110C000000) starts the TX interrupt >> flood (irq status: 0x20) immediately. Upon opening input as well as >> output the method snd_mpu401_do_reset is called - is perhaps the culprit >> somewhere there? > > Possibly. It write 0x00 to data at the beginning in > snd_mpu401_uart_cmd(). What happens if you remove it? > Unfortunately nothing, no change. Actually, when does the MPU_TX interrupt get thrown? Upon exhausting some output buffer? I understand interrupts for DMA, but mpu uart does not use DMA, right? Thanks a lot for help, I am not giving up :) Pavel. _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
