On Mon, 6 Mar 2006, Guennadi Liakhovetski wrote: > in drivers/pci/quirks.c: > > /* > * VIA Apollo KT133 needs PCI latency patch > * Made according to a windows driver based patch by George E. Breese > * see PCI Latency Adjust on > http://www.viahardware.com/download/viatweak.shtm > * Also see http://www.au-ja.org/review-kt133a-1-en.phtml for > * the info on which Mr Breese based his work. > * > * Updated based on further information from the site and also on > * information provided by VIA > */ > > and later: > > /* > * Ok we have the problem. Now set the PCI master grant to > * occur every master grant. The apparent bug is that under high > * PCI load (quite common in Linux of course) you can get data > * loss when the CPU is held off the bus for 3 bus master > requests > * This happens to include the IDE controllers.... > * > * VIA only apply this fix when an SB Live! is present but under > * both Linux and Windows this isnt enough, and we have seen > * corruption without SB Live! but with things like 3 UDMA IDE > * controllers. So we ignore that bit of the VIA recommendation.. > */ > > pci_read_config_byte(dev, 0x76, &busarb); > /* Set bit 4 and bi 5 of byte 76 to 0x01 > "Master priority rotation on every PCI master grant */ > busarb &= ~(1<<5); > busarb |= (1<<4); > pci_write_config_byte(dev, 0x76, busarb); > printk(KERN_INFO "Applying VIA southbridge workaround\n"); > > which in itself is wrong - the comment says "set bit 5 & 6 to 1", but > the code clears bit 6. Anyway, on my PC: > > 0000:00:07.0 ISA bridge: VIA Technologies, Inc. VT82C686 [Apollo Super South] > (rev 40) > 00: 06 11 86 06 87 00 10 02 40 00 01 06 00 00 80 00 > 10: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > 20: 00 00 00 00 00 00 00 00 00 00 00 00 43 10 e7 80 > 30: 00 00 00 00 c0 00 00 00 00 00 00 00 00 00 00 00 > 40: 08 01 00 00 00 80 62 e6 01 01 44 00 00 00 f0 f3 > 50: 0e 76 34 00 00 b0 5a 90 00 04 ff 08 d0 00 00 00 > 60: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > 70: 00 00 00 00 21 88 42 02 04 e4 00 00 00 00 00 00 > ^^ > 80: 01 00 00 00 00 09 00 00 00 60 00 00 00 00 00 00 > 90: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > c0: 01 00 02 00 00 00 00 00 00 00 00 00 00 00 00 00 > d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > f0: 00 00 00 00 00 00 41 00 00 00 00 00 00 00 00 00 > > So, bit 4 is not set... I added busarb to the printk above and it prints > 0xd2. Why is it reset to 0x42 again later??? Found nothing in > drivers/ide/pci/via82cxxx.c... I could read it back to check it did get > written.
Ok, my mistake. The quirk checks the southbridge revision, but configures byte 0x76 on the host (north) bridge, where it does get successfully set and remains set. But it doesn't seem to help. Still, at least the comment is wrong - it contradicts the code. Who is the author of that quirk? Any comments whether my problem seems similar to what others observed with this chipset? And my audio still doesn't work properly... Thanks Guennadi --- Guennadi Liakhovetski ------------------------------------------------------- This SF.Net email is sponsored by xPML, a groundbreaking scripting language that extends applications into web and mobile media. Attend the live webcast and join the prime developer group breaking into this new coding territory! http://sel.as-us.falkag.net/sel?cmd=lnk&kid=110944&bid=241720&dat=121642 _______________________________________________ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user