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Commit 1f9f9d16 authored by Heikki Krogerus's avatar Heikki Krogerus Committed by Greg Kroah-Hartman
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usb: typec: ucsi: acpi: Workaround for cache mode issue



This fixes an issue where the driver fails with an error:

	ioremap error for 0x3f799000-0x3f79a000, requested 0x2, got 0x0

On some platforms the UCSI ACPI mailbox SystemMemory
Operation Region may be setup before the driver has been
loaded. That will lead into the driver failing to map the
mailbox region, as it has been already marked as write-back
memory. acpi_os_ioremap() for x86 uses ioremap_cache()
unconditionally.

When the issue happens, the embedded controller has a
pending query event for the UCSI notification right after
boot-up which causes the operation region to be setup before
UCSI driver has been loaded.

The fix is to notify acpi core that the driver is about to
access memory region which potentially overlaps with an
operation region right before mapping it.
acpi_release_memory() will check if the memory has already
been setup (mapped) by acpi core, and deactivate it (unmap)
if it has. The driver is then able to map the memory with
ioremap_nocache() and set the memtype to uncached for the
region.

Reported-by: default avatarPaul Menzel <pmenzel@molgen.mpg.de>
Fixes: 8243edf4 ("usb: typec: ucsi: Add ACPI driver")
Cc: stable@vger.kernel.org
Signed-off-by: default avatarHeikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent d2d2e3c4
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