does setpci latency_timer fail on some mobos?

["Mark A. Miller" <mamillerpa@xxxxxxxxx>]

I have been experimenting with MythDora recently.  After experimenting
with assorted hardware and distros, my video is fairly good, but I get
an occasional hiccup, especially in action scenes.  When I try to set
the latency on the SATA controller to something high like AA, it stays
at 0 (see configuration and screendump below.)

My questions:
# Is the concept of PCI latency relevant on a PCIe system?  Are my
integrated controllers like the SATA on PCI or PCIe?
# Is it possible that some motherboards just refuse to change their
latency values?
# Is there some other I/O bottleneck I should be looking at?

Thanks so much in advance,
Mark


My current system:
	Asus M2N-E AM2/DDR2/PCIe mobo
	MythDora 4.0
	eVGA PCIe e-GeForce 7600 GT video card
	WD Raptor 10k RPM 75 GB SATA/300
	Athlon 64 X2 3600+
	Hauppauge WinTV-PVR-150
	2x 1 GB sticks of SimpleTech PC3200 DDR2

Here's a transcript of what I'm trying to do:

[root@localhost ~]# lspci -s 00:05.0 -v
00:05.0 IDE interface: nVidia Corporation MCP55 SATA Controller (rev
a2) (prog-if 85 [Master SecO PriO])
        Subsystem: ASUSTeK Computer Inc. Unknown device 8239
        Flags: bus master, 66MHz, fast devsel, latency 0, IRQ 18
        I/O ports at 09f0 [size=8]
        I/O ports at 0bf0 [size=4]
        I/O ports at 0970 [size=8]
        I/O ports at 0b70 [size=4]
        I/O ports at dc00 [size=16]
        Memory at fe02d000 (32-bit, non-prefetchable) [size=4K]
        Capabilities: [44] Power Management version 2
        Capabilities: [b0] Message Signalled Interrupts: 64bit+
Queue=0/2 Enable-
        Capabilities: [cc] HyperTransport: MSI Mapping

[root@localhost ~]# setpci -v -s 00:05.1 latency_timer=AA
00:05.1:0d aa
[root@localhost ~]# lspci -s 00:05.0 -v
00:05.0 IDE interface: nVidia Corporation MCP55 SATA Controller (rev
a2) (prog-if 85 [Master SecO PriO])
        Subsystem: ASUSTeK Computer Inc. Unknown device 8239
        Flags: bus master, 66MHz, fast devsel, latency 0, IRQ 18
        I/O ports at 09f0 [size=8]
        I/O ports at 0bf0 [size=4]
        I/O ports at 0970 [size=8]
        I/O ports at 0b70 [size=4]
        I/O ports at dc00 [size=16]
        Memory at fe02d000 (32-bit, non-prefetchable) [size=4K]
        Capabilities: [44] Power Management version 2
        Capabilities: [b0] Message Signalled Interrupts: 64bit+
Queue=0/2 Enable-
        Capabilities: [cc] HyperTransport: MSI Mapping