Date: Sat, 4 Dec 2004 14:23:36 +0100 From: "Daan Vreeken [PA4DAN]" <Danovitsch@vitsch.net> To: FreeBSD-Hackers@FreeBSD.org Subject: Problem (interrupt storm) with snd_ich Message-ID: <200412041423.36735.Danovitsch@vitsch.net>
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Hi All,
I'm having a problem with the snd_ich driver. Directly after loading the
snd_ich module pcm0 is detected correctly, but "vmstat -i" shows about 40000
interrupts every second caused by pcm0.
The problem shows up with both custom kernels and GENERIC, with or without
snd_ich compiled into the kernel.
After adding a printf() to the ich_intr() routine it showed that all
interrupts have 0x400 (ICH_GLOB_STA_PRES) set. The ich_intr() has a comment
about clearing this interrupt in the following lines :
/* Clear resume interrupt(s) - nothing doing with them */
ich_wr(sc, ICH_REG_GLOB_STA, gs, 4);
Although this code should clear the interrupt, this doesn't seem to work on my
laptop somehow.
In ich_init() ICH_GLOB_CTL_PRES gets set in the ICH_REG_GLOB_CNT register. If
I remove this bit in ich_init(), the interrupt problem goes away and pcm0
works as expected. I have changed the following line in ich_init() :
Original line :
ich_wr(sc, ICH_REG_GLOB_CNT, ICH_GLOB_CTL_COLD | ICH_GLOB_CTL_PRES, 4);
New line :
ich_wr(sc, ICH_REG_GLOB_CNT, ICH_GLOB_CTL_COLD, 4);
I'm not an ICH expert, so I don't know if I have just disabled a
suspend/resume feature that is really needed or not, but it does solve my
problem. I would like to know if anyone else has seen this problem before,
and if there is a better solution to it.
The relevant part of "pciconf -lv" :
pcm0@pci0:2:7: class=0x040100 card=0x17631043 chip=0x70121039 rev=0xa0
hdr=0x00
vendor = 'Silicon Integrated Systems (SiS)'
device = 'SiS7012 PCI Audio Accelerator'
class = multimedia
subclass = audio
Feel free to ask for more information. I'm willing to test patches and give
feedback.
Thanks,
Daan
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