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    SubjectRe: [PATCH v4 12/19] cpufreq: cpufreq-cpu0: remove device tree parsing for cpu nodes
    On 06/09/13 14:44, Guennadi Liakhovetski wrote:
    > Hi
    >
    > On Tue, 20 Aug 2013, Sudeep KarkadaNagesha wrote:
    >
    >> From: Sudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com>
    >>
    >> Now that the cpu device registration initialises the of_node(if available)
    >> appropriately for all the cpus, parsing here is redundant.
    >>
    >> This patch removes all DT parsing and uses cpu->of_node instead.
    >>
    >> Acked-by: Shawn Guo <shawn.guo@linaro.org>
    >> Acked-by: Rob Herring <rob.herring@calxeda.com>
    >> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
    >> Signed-off-by: Sudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com>
    >> ---
    >> drivers/cpufreq/cpufreq-cpu0.c | 23 ++++-------------------
    >> 1 file changed, 4 insertions(+), 19 deletions(-)
    >>
    >> diff --git a/drivers/cpufreq/cpufreq-cpu0.c b/drivers/cpufreq/cpufreq-cpu0.=
    >> c
    >> index ad1fde2..5b05c26 100644
    >> --- a/drivers/cpufreq/cpufreq-cpu0.c
    >> +++ b/drivers/cpufreq/cpufreq-cpu0.c
    >> @@ -174,29 +174,17 @@ static struct cpufreq_driver cpu0_cpufreq_driver =3D =
    >> {
    >> =20
    >> static int cpu0_cpufreq_probe(struct platform_device *pdev)
    >> {
    >> -=09struct device_node *np, *parent;
    >> +=09struct device_node *np;
    >> =09int ret;
    >> =20
    >> -=09parent =3D of_find_node_by_path("/cpus");
    >> -=09if (!parent) {
    >> -=09=09pr_err("failed to find OF /cpus\n");
    >> -=09=09return -ENOENT;
    >> -=09}
    >> -
    >> -=09for_each_child_of_node(parent, np) {
    >> -=09=09if (of_get_property(np, "operating-points", NULL))
    >> -=09=09=09break;
    >> -=09}
    >> +=09cpu_dev =3D &pdev->dev;
    >> =20
    >> +=09np =3D of_node_get(cpu_dev->of_node);
    >
    > Has this actually been tested? This seems to break cpufreq-cpu0. The
    > reason is, that this probe function is called not for the DT CPU node, but
    > for a special virtual cpufreq-cpu0 platform device, typically created by
    > platforms, using
    >
    > platform_device_register_simple("cpufreq-cpu0", -1, NULL, 0);
    >
    > which then of course doesn't have on .of_node associated with it.
    >

    Hi Guennadi,

    Based on my understanding of the original code:
    cpu_dev = &pdev->dev;
    ...
    ret = of_init_opp_table(cpu_dev);

    of_init_opp_table needs cpu_dev to be get_cpu_device(0). My
    understanding was that platform using cpufreq-cpu0 sets &pdev->dev to
    get_cpu_device(0). But looks like that's not the case.

    Hi Shawn,

    Can you please clarify ? The fix would be as below but I would like to
    know if setting cpu_dev to get_cpu_device(0) instead of &pdev->dev has
    any impact on other parts of code using cpu_dev ?

    diff --git a/drivers/cpufreq/cpufreq-cpu0.c b/drivers/cpufreq/cpufreq-cpu0.c
    index cbfffa9..871c336 100644
    --- a/drivers/cpufreq/cpufreq-cpu0.c
    +++ b/drivers/cpufreq/cpufreq-cpu0.c
    @@ -177,7 +177,7 @@ static int cpu0_cpufreq_probe(struct platform_device
    *pdev)
    struct device_node *np;
    int ret;

    - cpu_dev = &pdev->dev;
    + cpu_dev = get_cpu_device(0);

    np = of_node_get(cpu_dev->of_node);
    if (!np) {

    Regards,
    Sudeep





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