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authorHans de Goede2021-12-03 12:51:08 +0100
committerLee Jones2021-12-29 13:17:01 +0000
commite6b142060b24014bfcf86ae5b1facc5e99e84176 (patch)
tree8a1ed12bd74602ef706b4e7daa313a3783629bf7 /crypto/pcrypt.c
parentad4ddfac646a9e177cb322e7234d87ed4f282da4 (diff)
mfd: intel-lpss: Fix I2C4 not being available on the Microsoft Surface Go & Go 2
Many DSDTs for Kaby Lake and Kaby Lake Refresh models contain a _SB.PCI0.GEXP ACPI Device node describing an I2C attached PCA953x GPIO expander. This seems to be something which is copy and pasted from the DSDT from some reference design since this ACPI Device is present even on models where no such GPIO expander is used at all, such as on the Microsoft Surface Go & Go 2. This ACPI Device is a problem because it contains a SystemMemory OperationRegion which covers the MMIO for the I2C4 I2C controller. This causes the MFD cell for the I2C4 controller to not be instantiated due to a resource conflict, requiring the use of acpi_enforce_resources=lax to work around this. I have done an extensive analysis of all the ACPI tables on the Microsoft Surface Go and the _SB.PCI0.GEXP ACPI Device's methods are not used by any code in the ACPI tables, neither are any of them directly called by any Linux kernel code. This is unsurprising since running i2cdetect on the I2C4 bus shows that there is no GPIO expander chip present on these devices at all. This commit adds a PCI subsystem vendor:device table listing PCI devices where it is known to be safe to ignore resource conflicts with ACPI declared SystemMemory regions. This makes the I2C4 bus work out of the box on the Microsoft Surface Go & Go 2, which is necessary for the cameras on these devices to work. Signed-off-by: Hans de Goede <hdegoede@redhat.com> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com> Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com> Signed-off-by: Lee Jones <lee.jones@linaro.org> Link: https://lore.kernel.org/r/20211203115108.89661-1-hdegoede@redhat.com
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