* Re: htpt366 PCI latency value is really high
[not found] <20070426064927.13d0ed72@reforged>
@ 2007-04-26 14:30 ` Sergei Shtylyov
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From: Sergei Shtylyov @ 2007-04-26 14:30 UTC (permalink / raw)
To: Mike Mattie; +Cc: linux-kernel, linux-ide
Hello.
Mike Mattie wrote:
> while hunting down some latency problems I found something quite odd.
> The latency reported by lspci -v for the HTP203N card is enormous.
> 00:09.0 RAID bus controller: Triones Technologies, Inc. HPT302/302N
> (rev 02) Subsystem: Triones Technologies, Inc. Unknown device 0001
> Flags: bus master, 66MHz, medium devsel, latency 120, IRQ 17
> I/O ports at ec00 [size=8]
> I/O ports at e800 [size=4]
> I/O ports at e400 [size=8]
> I/O ports at e000 [size=4]
> I/O ports at dc00 [size=256]
> Expansion ROM at dffe0000 [disabled by cmd] [size=128K]
> Capabilities: [60] Power Management version 2
> I am assuming that the "latency" field here is the PCI latency timer
> which means this card is a bus hog.
> From some reading on this issue linux methodically sets a sane value for
> all the PCI cards it sets up, which looks normal on the rest of the system,
> which is set to the value: 32
Hm, I'm only seeing clamping to the smallest of 64 and pcibios_max_latency (255) in arch/i386/pci/i386.c if the latency value is too low... Which arch are you using?
> setting the value 32 with:
> setpci -v -s "00:09.0" latency_timer=32
> 00:09.0 RAID bus controller: Triones Technologies, Inc. HPT302/302N (rev 02)
> Subsystem: Triones Technologies, Inc. Unknown device 0001
> Flags: bus master, 66MHz, medium devsel, latency 48, IRQ 17
> I/O ports at ec00 [size=8]
> I/O ports at e800 [size=4]
> I/O ports at e400 [size=8]
> I/O ports at e000 [size=4]
> I/O ports at dc00 [size=256]
> Expansion ROM at dffe0000 [disabled by cmd] [size=128K]
> Capabilities: [60] Power Management version 2
> Results in 48, which is not what I asked, but hopefully this is
> linux doing the right thing.
Not sure -- seems likely that it's the chip's own enforced minimum instead...
> I know this chipset is pretty brain-damaged, but is this
> high latency value a work-around for broken hardware, or
More like it. Although HighPoint's own drivers force 64.
> just a oversight ?
Not likely since the value is too "special"...
> Cheers,
> Mike Mattie - codermattie@gmail.com
WBR, Sergei
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