[mythtv-users] Trouble with two HD-PVRs on one system

[John P Poet]

On Wed, Nov 11, 2009 at 5:06 PM, David Engel <david at istwok.net> wrote:
> On Mon, Nov 09, 2009 at 06:04:27PM -0600, David Engel wrote:
>> I'm going to try other cabling combinations tomorrow to see if I can
>> figure out what's going on.  At this point, I think the leasting cause
>> is that my system is just cursed! :)
>
> Cursed is still in the running, but this is looking more and more like
> it's probably a motherboard and/or host controller problem.
>
> First, having both HD-PVRs connected through an external hub to my
> development system works fine.  Good.  It should work with my
> production backend then too, so back to it.
>
> Much trial and error revealed that the HD-PVRs will not flake out
> unless one is connected to the back panel and the other is connected
> to the front panel.  Connecting both with or without an external hub
> to either the back panel or the front panel results in flakiness.
>
> It turns out my motherboard has two EHCI controllers.  One handles the
> back panel ports and the other handles the internal/front panel ports.
> Further testing showed having any other high speed USB device attached
> to the same controller as an HD-PVR will cause problems.  For example,
> accessing a USB flash drive will cause the HD-PVR to flake out.
> Strangely, the HD-PVR activity does not seem to affect the flash
> drive.  Is it possible the HD-PVR driver is too sensitive to
> contention on the bus?
>
> Anyway, the motherboard is a Biostar TA790GXB A2+ with an ATI
> SB700/SB800 south bridge.  I tried searching for USB problems with for
> that board and chipset and nothing like mine came up.  Does anyone
> know of some low-level USB or PCI settings that might be worth
> tweaking.

Sorry, I don't.

The whole reason I brought up the possibility of USB being the
problem, is my old Asus socket 478 motherboard gave me similar grief.
Once I switched to a Gigabyte socket 775 motherboard, those problems
went away.

John
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