[PATCH 6.18.y 3/3] ACPI: scan: Do not combine resources that overlap completely

[Ting-Han Hou <ue081723@gmail.com>]

From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>

[ Upstream commit 7617cc05df28dcae967cca109de74084321eaa62 ]

Commit f234fdaae1ca ("ACPI: scan: Avoid registering platform devices
with resource overlaps") attempted to avoid platform device registration
errors due to overlaps of resources of the same type returned by the
same _CRS object in the ACPI tables.  It did that by combining two or
more overlapping resources into one, but it went too far and also
caused resources that overlap completely to be combined which broke
the arm-cmn driver that expects two MMIO resources to be present for
each device it binds to and it expects those two resources to overlap
completely.

Address this issue by adding checks for completely overlapping
resources to acpi_platform_adjust_resources() and add a comment
explaining what is done there.

Fixes: f234fdaae1ca ("ACPI: scan: Avoid registering platform devices with resource overlaps")
Reported-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Closes: https://lore.kernel.org/linux-acpi/20260819003752.GA3063251@ax162/
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Link: https://patch.msgid.link/12955564.O9o76ZdvQC@rafael.j.wysocki
[ Ting-Han: __resource_contains_unbound() was added by edfaa81d5da5
  ("resource: Add __resource_contains_unbound() for internal contains
  checks"), which is not in 6.18.y, so use resource_contains() instead.
  The two only differ in the IORESOURCE_UNSET check, and the resources
  returned by acpi_dev_get_resources() never have IORESOURCE_UNSET set:
  it is only set together with IORESOURCE_DISABLED, and disabled
  resources are not added to the list. ]
Signed-off-by: Ting-Han Hou <ue081723@gmail.com>
---
 drivers/acpi/acpi_platform.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/acpi/acpi_platform.c b/drivers/acpi/acpi_platform.c
index abdd8893e..29b197440 100644
--- a/drivers/acpi/acpi_platform.c
+++ b/drivers/acpi/acpi_platform.c
@@ -85,7 +85,13 @@ static unsigned int acpi_platform_adjust_resources(struct acpi_device *adev,
 	for (i = 0; i < count; ) {
 		struct resource *res = &resources[i];
 
-		if (resource_type(new_res) != resource_type(res) ||
+		/*
+		 * Look for overlaps of resources of the same type that would
+		 * cause resource insertion to fail down the road.
+		 */
+		if (resource_contains(res, new_res) ||
+		    resource_contains(new_res, res) ||
+		    resource_type(new_res) != resource_type(res) ||
 		    !resource_union(new_res, res, new_res)) {
 			i++;
 			continue;
-- 
2.53.0