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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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