[PATCH 3/5] cxl/acpi: Minimize granularity for x1 interleaves

[Dan Williams <dan.j.williams@intel.com>]

The kernel enforces that region granularity is >= to the top-level
interleave-granularity for the given CXL window. However, when the CXL
window interleave is x1, i.e. non-interleaved at the host bridge level,
then the specified granularity does not matter. Override the window
specified granularity to the CXL minimum so that any valid region
granularity is >= to the root granularity.

Reported-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 drivers/cxl/acpi.c |    6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
index eb436268b92c..67137e17b8c9 100644
--- a/drivers/cxl/acpi.c
+++ b/drivers/cxl/acpi.c
@@ -140,6 +140,12 @@ static int cxl_parse_cfmws(union acpi_subtable_headers *header, void *arg,
 		.end = res->end,
 	};
 	cxld->interleave_ways = ways;
+	/*
+	 * Minimize the x1 granularity to advertise support for any
+	 * valid region granularity
+	 */
+	if (ways == 1)
+		ig = 256;
 	cxld->interleave_granularity = ig;
 
 	rc = cxl_decoder_add(cxld, target_map);