Messages in this thread | | | Date | Mon, 17 May 2010 18:56:30 -0600 | From | Robert Hancock <> | Subject | Re: [PATCH] x86: Disable HPET MSI on ATI SB700/SB800 |
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On 05/17/2010 08:59 AM, Andreas Herrmann wrote: > On Mon, Jan 25, 2010 at 06:10:59PM +0100, Andreas Herrmann wrote: >> On Fri, Jan 22, 2010 at 11:21:06PM -0800, Yuhong Bao wrote: >>> >>>> HPET MSI on platforms with ATI SB700/SB800 as they seem to have some >>>> side-effects on floppy DMA. Do not use HPET MSI on such platforms. >> >> Argh, will see what information I can find about this problem ... > > FYI. I've tried to trigger the publication of errata information for that > chipset. Finally this has happened. > > The discussed problem is indeed due to an erratum. See erratum #27 in > http://support.amd.com/us/Embedded_TechDocs/46837.pdf > > The suggested workaround for this is to disable HPET MSI if LPC > devices are used. I doubt that there is a convenient way for Linux to > find out whether LPC devices are used. Thus I think the only solution > to safely avoid the problem is the currently implemented quirk to > disable HPET MSI on this chipset.
If one wanted, you could disable HPET MSI on this chipset only when a driver requests an ISA DMA channel. Then if there's no floppy or other LPC DMA device present, it can stay enabled. I don't know if it's worth the trouble, though.
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