Messages in this thread | | | From | "Rafael J. Wysocki" <> | Date | Fri, 18 May 2018 22:04:02 +0200 | Subject | Re: `ucsi_acpi: probe of USBC000:00 failed with error -12` on Dell XPS 13 9360/9370 |
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On Fri, May 18, 2018 at 5:15 PM, Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote: > On Fri, May 18, 2018 at 06:08:24PM +0300, Heikki Krogerus wrote: >> >> Rafael, the problem here with these Dell laptops is that a memory page >> that is used as a mailbox for special communication between EC FW and >> OS (called UCSI mailbox) should be in uncached memory, but the memory >> is marked as cached.
Well, why don't we map it as uncached, then?
>> I'm actually not even sure if the cache mode is something that is set >> based on information from ACPI tables, or is it something that the >> BIOS handles separately?
We map the ACPI tables as cached as a rule, so that may be the reason.
>> If it's information coming from ACPI tables, can we help pin point the >> place the BIOS guys at Dell should fix?
I'm not sure where this particular piece comes from.
> Given that Windows works with this same set of ACPI tables, perhaps the > requirement isn't that this memory location be uncached? > > We shouldn't have to fix up ACPI tables just for Linux, we've been down > that path before :(
Yes, pretty much.
Thanks, Rafael
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