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    Subject[PATCH 5.16 0325/1017] cpuidle: qcom-spm: Check if any CPU is managed by SPM
    Date
    From: Stephan Gerhold <stephan@gerhold.net>

    [ 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@samsung.com>
    Link: https://lore.kernel.org/r/86e3e09f-a8d7-3dff-3fc6-ddd7d30c5d78@samsung.com/
    Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
    Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
    Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
    Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
    Link: https://lore.kernel.org/r/20211201130505.257379-2-stephan@gerhold.net
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    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)) {
    --
    2.34.1


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