Patch "drivers: base: cacheinfo: fix boot error message when acpi is enabled" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

drivers: base: cacheinfo: fix boot error message when acpi is enabled

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
drivers-base-cacheinfo-fix-boot-error-message-when-acpi-is-enabled.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Sudeep Holla <[email protected]>
Date: Fri, 28 Oct 2016 09:45:29 +0100
Subject: drivers: base: cacheinfo: fix boot error message when acpi is enabled

From: Sudeep Holla <[email protected]>

commit 55877ef45fbd7f975d078426866b7d1a2435dcc3 upstream.

ARM64 enables both CONFIG_OF and CONFIG_ACPI and the firmware can pass both ACPI tables and the device tree. Based on the kernel parameter, one of the two will be chosen. If acpi is enabled, then device tree is not unflattened.

Currently ARM64 platforms report:
"
Failed to find cpu0 device node
Unable to detect cache hierarchy from DT for CPU 0
"
which is incorrect when booting with ACPI. Also latest ACPI v6.1 has no support for cache properties/hierarchy.

This patch adds check for unflattened device tree and also returns as "not supported" if ACPI is runtime enabled.

It also removes the reference to DT from the error message as the cache hierarchy can be detected from the firmware(OF/DT/ACPI)

---
 drivers/base/cacheinfo.c |   12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

@@ -16,6 +16,7 @@
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
+#include <linux/acpi.h>
 #include <linux/bitops.h>
 #include <linux/cacheinfo.h>
 #include <linux/compiler.h>

@@ -104,12 +105,16 @@ static int cache_shared_cpu_map_setup(un
 	struct cpu_cacheinfo *this_cpu_ci = get_cpu_cacheinfo(cpu);
 	struct cacheinfo *this_leaf, *sib_leaf;
 	unsigned int index;
-	int ret;
+	int ret = 0;
 
 	if (this_cpu_ci->cpu_map_populated)
 		return 0;
 
-	ret = cache_setup_of_node(cpu);
+	if (of_have_populated_dt())
+		ret = cache_setup_of_node(cpu);
+	else if (!acpi_disabled)
+		/* No cache property/hierarchy support yet in ACPI */
+		ret = -ENOTSUPP;
 	if (ret)
 		return ret;
 

@@ -206,8 +211,7 @@ static int detect_cache_attributes(unsig
 	 */
 	ret = cache_shared_cpu_map_setup(cpu);
 	if (ret) {
-		pr_warn("Unable to detect cache hierarchy from DT for CPU %d\n",
-			cpu);
+		pr_warn("Unable to detect cache hierarchy for CPU %d\n", cpu);
 		goto free_ci;
 	}
 	return 0;

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/drivers-base-cacheinfo-fix-x86-with-config_of-enabled.patch queue-4.9/drivers-base-cacheinfo-fix-boot-error-message-when-acpi-is-enabled.patch