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    SubjectRe: [PATCH v16 14/15] clocksource/drivers/arm_arch_timer: Add GTDT support for memory-mapped timer
    On Wed, Nov 16, 2016 at 09:49:07PM +0800, fu.wei@linaro.org wrote:
    > From: Fu Wei <fu.wei@linaro.org>
    >
    > The patch add memory-mapped timer register support by using the
    > information provided by the new GTDT driver of ACPI.
    >
    > Signed-off-by: Fu Wei <fu.wei@linaro.org>
    > ---
    > drivers/clocksource/arm_arch_timer.c | 26 +++++++++++++++++++++++++-
    > 1 file changed, 25 insertions(+), 1 deletion(-)
    >
    > diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
    > index c494ca8..0aad60a 100644
    > --- a/drivers/clocksource/arm_arch_timer.c
    > +++ b/drivers/clocksource/arm_arch_timer.c
    > @@ -1067,7 +1067,28 @@ CLOCKSOURCE_OF_DECLARE(armv7_arch_timer_mem, "arm,armv7-timer-mem",
    > arch_timer_mem_of_init);
    >
    > #ifdef CONFIG_ACPI_GTDT
    > -/* Initialize per-processor generic timer */
    > +static int __init arch_timer_mem_acpi_init(void)
    > +{
    > + struct arch_timer_mem *timer_mem;
    > + int ret = 0;
    > + int i = 0;
    > +
    > + timer_mem = kzalloc(sizeof(*timer_mem), GFP_KERNEL);

    Why do you need it zeroed? You don't clear it between iterations, so
    either you don't need this, or you have a bug in the loop.

    > + if (!timer_mem)
    > + return -ENOMEM;
    > +
    > + while (!gtdt_arch_timer_mem_init(timer_mem, i)) {

    Huh?

    Why doesn't GTDT expose a function to fill in the entire arch_timer_mem
    in one go?

    There shouldn't be multiple instances, as far as I am aware. Am I
    mistaken?

    > + ret = arch_timer_mem_init(timer_mem);
    > + if (ret)
    > + break;
    > + i++;
    > + }
    > +
    > + kfree(timer_mem);
    > + return ret;
    > +}


    Regardless, arch_timer_mem is small enough that you don't need dynamic
    allocaiton. Just put it on the stack, e.g.

    static int __init arch_timer_mem_acpi_init(void)
    {
    int i = 0;
    struct arch_timer_mem timer_mem;

    while (!gtdt_arch_timer_mem_init(timer_mem, i)) {
    int ret = arch_timer_mem_init();
    if (ret)
    return ret;
    i++
    }

    return 0;
    }

    Thanks,
    Mark.

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