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%3Ba=su...

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 stable@vger.kernel.org know about it.

From 55877ef45fbd7f975d078426866b7d1a2435dcc3 Mon Sep 17 00:00:00 2001

From: Sudeep Holla sudeep.holla@arm.com Date: Fri, 28 Oct 2016 09:45:29 +0100 Subject: drivers: base: cacheinfo: fix boot error message when acpi is enabled

From: Sudeep Holla sudeep.holla@arm.com

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)

Cc: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sudeep Holla sudeep.holla@arm.com Signed-off-by: Mian Yousaf Kaukab yousaf.kaukab@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

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

--- a/drivers/base/cacheinfo.c +++ b/drivers/base/cacheinfo.c @@ -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 sudeep.holla@arm.com 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