[PATCH 5.16 0325/1017] cpuidle: qcom-spm: Check if any CPU is managed by SPM

From: Greg Kroah-Hartman
Date: Tue Apr 05 2022 - 08:16:47 EST

From: Stephan Gerhold <stephan@xxxxxxxxxxx>

[ Upstream commit 0ee30ace67e425ab83a1673bf51f50b577328cf9 ]

At the moment, the "qcom-spm-cpuidle" platform device is always created,
even if none of the CPUs is actually managed by the SPM. On non-qcom
platforms this will result in infinite probe-deferral due to the
failing qcom_scm_is_available() call.

To avoid this, look through the CPU DT nodes and check if there is
actually any CPU managed by a SPM (as indicated by the qcom,saw property).
It should also be available because e.g. MSM8916 has qcom,saw defined
but it's typically not enabled with ARM64/PSCI firmwares.

This is needed in preparation of a follow-up change that calls
qcom_scm_set_warm_boot_addr() a single time before registering any
cpuidle drivers. Otherwise this call might be made even on devices
that have this driver enabled but actually make use of PSCI.

Fixes: 60f3692b5f0b ("cpuidle: qcom_spm: Detach state machine from main SPM handling")
Reported-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
Link: https://lore.kernel.org/r/86e3e09f-a8d7-3dff-3fc6-ddd7d30c5d78@xxxxxxxxxxx/
Signed-off-by: Stephan Gerhold <stephan@xxxxxxxxxxx>
Tested-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
Acked-by: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
Signed-off-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20211201130505.257379-2-stephan@xxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
drivers/cpuidle/cpuidle-qcom-spm.c | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)

diff --git a/drivers/cpuidle/cpuidle-qcom-spm.c b/drivers/cpuidle/cpuidle-qcom-spm.c
index 01e77913a414..5f27dcc6c110 100644
--- a/drivers/cpuidle/cpuidle-qcom-spm.c
+++ b/drivers/cpuidle/cpuidle-qcom-spm.c
@@ -155,6 +155,22 @@ static struct platform_driver spm_cpuidle_driver = {

+static bool __init qcom_spm_find_any_cpu(void)
+ struct device_node *cpu_node, *saw_node;
+ for_each_of_cpu_node(cpu_node) {
+ saw_node = of_parse_phandle(cpu_node, "qcom,saw", 0);
+ if (of_device_is_available(saw_node)) {
+ of_node_put(saw_node);
+ of_node_put(cpu_node);
+ return true;
+ }
+ of_node_put(saw_node);
+ }
+ return false;
static int __init qcom_spm_cpuidle_init(void)
struct platform_device *pdev;
@@ -164,6 +180,10 @@ static int __init qcom_spm_cpuidle_init(void)
if (ret)
return ret;

+ /* Make sure there is actually any CPU managed by the SPM */
+ if (!qcom_spm_find_any_cpu())
+ return 0;
pdev = platform_device_register_simple("qcom-spm-cpuidle",
-1, NULL, 0);
if (IS_ERR(pdev)) {