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Re: [PATCH v16 14/15] clocksource/drivers/arm_arch_timer: Add GTDT support for memory-mapped timer

From Mark Rutland <mark.rutland@arm.com>
Newsgroups linux.kernel
Subject Re: [PATCH v16 14/15] clocksource/drivers/arm_arch_timer: Add GTDT support for memory-mapped timer
Date 2016-11-18 21:30 +0100
Message-ID <sEXXk-3vd-9@gated-at.bofh.it> (permalink)
References <sE8L7-3uw-15@gated-at.bofh.it> <sE8UO-3xZ-53@gated-at.bofh.it>
Organization linux.* mail to news gateway

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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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Thread

[PATCH v16 00/15] acpi, clocksource: add GTDT driver and GTDT support in arm_arch_timer fu.wei@linaro.org - 2016-11-16 14:50 +0100
  [PATCH v16 07/15] clocksource/drivers/arm_arch_timer: Refactor arch_timer_detect_rate to keep dt code in *_of_init fu.wei@linaro.org - 2016-11-16 15:00 +0100
    Re: [PATCH v16 07/15] clocksource/drivers/arm_arch_timer: Refactor  arch_timer_detect_rate to keep dt code in *_of_init Mark Rutland <mark.rutland@arm.com> - 2016-11-18 21:00 +0100
      Re: [PATCH v16 07/15] clocksource/drivers/arm_arch_timer: Refactor  arch_timer_detect_rate to keep dt code in *_of_init Fu Wei <fu.wei@linaro.org> - 2016-11-21 15:10 +0100
  [PATCH v16 12/15] clocksource/drivers/arm_arch_timer: Simplify ACPI support code. fu.wei@linaro.org - 2016-11-16 15:00 +0100
  [PATCH v16 13/15] acpi/arm64: Add memory-mapped timer support in GTDT driver fu.wei@linaro.org - 2016-11-16 15:00 +0100
    Re: [PATCH v16 13/15] acpi/arm64: Add memory-mapped timer support in  GTDT driver Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> - 2016-11-18 15:30 +0100
      Re: [PATCH v16 13/15] acpi/arm64: Add memory-mapped timer support in  GTDT driver Fu Wei <fu.wei@linaro.org> - 2016-11-23 13:00 +0100
        Re: [PATCH v16 13/15] acpi/arm64: Add memory-mapped timer support in  GTDT driver Fu Wei <fu.wei@linaro.org> - 2016-11-24 05:00 +0100
  [PATCH v16 10/15] clocksource/drivers/arm_arch_timer: Refactor the timer init code to prepare for GTDT fu.wei@linaro.org - 2016-11-16 15:00 +0100
    Re: [PATCH v16 10/15] clocksource/drivers/arm_arch_timer: Refactor  the timer init code to prepare for GTDT Mark Rutland <mark.rutland@arm.com> - 2016-11-18 21:10 +0100
      Re: [PATCH v16 10/15] clocksource/drivers/arm_arch_timer: Refactor  the timer init code to prepare for GTDT Fu Wei <fu.wei@linaro.org> - 2016-11-23 07:20 +0100
  [PATCH v16 11/15] acpi/arm64: Add GTDT table parse driver fu.wei@linaro.org - 2016-11-16 15:00 +0100
    Re: [PATCH v16 11/15] acpi/arm64: Add GTDT table parse driver Mark Rutland <mark.rutland@arm.com> - 2016-11-18 21:20 +0100
      Re: [PATCH v16 11/15] acpi/arm64: Add GTDT table parse driver Fu Wei <fu.wei@linaro.org> - 2016-11-23 13:10 +0100
  [PATCH v16 04/15] clocksource/drivers/arm_arch_timer: rename some enums and defines, and some cleanups. fu.wei@linaro.org - 2016-11-16 15:00 +0100
    Re: [PATCH v16 04/15] clocksource/drivers/arm_arch_timer: rename  some enums and defines, and some cleanups. Mark Rutland <mark.rutland@arm.com> - 2016-11-18 20:00 +0100
      Re: [PATCH v16 04/15] clocksource/drivers/arm_arch_timer: rename some  enums and defines, and some cleanups. Fu Wei <fu.wei@linaro.org> - 2016-11-21 07:20 +0100
  [PATCH v16 01/15] clocksource/drivers/arm_arch_timer: Move enums and defines to header file fu.wei@linaro.org - 2016-11-16 15:00 +0100
  [PATCH v16 15/15] acpi/arm64: Add SBSA Generic Watchdog support in GTDT driver fu.wei@linaro.org - 2016-11-16 15:00 +0100
  [PATCH v16 14/15] clocksource/drivers/arm_arch_timer: Add GTDT support for memory-mapped timer fu.wei@linaro.org - 2016-11-16 15:00 +0100
    Re: [PATCH v16 14/15] clocksource/drivers/arm_arch_timer: Add GTDT  support for memory-mapped timer Mark Rutland <mark.rutland@arm.com> - 2016-11-18 21:30 +0100
      Re: [PATCH v16 14/15] clocksource/drivers/arm_arch_timer: Add GTDT  support for memory-mapped timer Fu Wei <fu.wei@linaro.org> - 2016-11-23 13:20 +0100
  [PATCH v16 08/15] clocksource/drivers/arm_arch_timer: Refactor arch_timer_needs_probing, and call it only if acpi disabled. fu.wei@linaro.org - 2016-11-16 15:00 +0100
    Re: [PATCH v16 08/15] clocksource/drivers/arm_arch_timer: Refactor  arch_timer_needs_probing, and call it only if acpi disabled. Mark Rutland <mark.rutland@arm.com> - 2016-11-18 21:00 +0100
      Re: [PATCH v16 08/15] clocksource/drivers/arm_arch_timer: Refactor  arch_timer_needs_probing, and call it only if acpi disabled. Fu Wei <fu.wei@linaro.org> - 2016-11-21 15:40 +0100
  [PATCH v16 06/15] clocksource/drivers/arm_arch_timer: separate out arch_timer_uses_ppi init code to prepare for GTDT. fu.wei@linaro.org - 2016-11-16 15:00 +0100
    Re: [PATCH v16 06/15] clocksource/drivers/arm_arch_timer: separate  out arch_timer_uses_ppi init code to prepare for GTDT. Mark Rutland <mark.rutland@arm.com> - 2016-11-18 20:40 +0100
      Re: [PATCH v16 06/15] clocksource/drivers/arm_arch_timer: separate  out arch_timer_uses_ppi init code to prepare for GTDT. Fu Wei <fu.wei@linaro.org> - 2016-11-21 10:50 +0100
  [PATCH v16 03/15] clocksource/drivers/arm_arch_timer: Improve printk relevant code fu.wei@linaro.org - 2016-11-16 15:00 +0100
  [PATCH v16 02/15] clocksource/drivers/arm_arch_timer: Add a new enum for spi type fu.wei@linaro.org - 2016-11-16 15:00 +0100
  [PATCH v16 09/15] clocksource/drivers/arm_arch_timer: Introduce some new structs to prepare for GTDT fu.wei@linaro.org - 2016-11-16 15:00 +0100
  [PATCH v16 05/15] clocksource/drivers/arm_arch_timer: fix a bug in arch_timer_register about arch_timer_uses_ppi fu.wei@linaro.org - 2016-11-16 15:00 +0100
    Re: [PATCH v16 05/15] clocksource/drivers/arm_arch_timer: fix a bug  in arch_timer_register about arch_timer_uses_ppi Mark Rutland <mark.rutland@arm.com> - 2016-11-18 20:00 +0100
      Re: [PATCH v16 05/15] clocksource/drivers/arm_arch_timer: fix a bug  in arch_timer_register about arch_timer_uses_ppi Fu Wei <fu.wei@linaro.org> - 2016-11-21 08:40 +0100
  Re: [PATCH v16 00/15] acpi, clocksource: add GTDT driver and GTDT  support in arm_arch_timer Xiongfeng Wang <wangxiongfeng2@huawei.com> - 2016-11-17 04:50 +0100
    Re: [PATCH v16 00/15] acpi, clocksource: add GTDT driver and GTDT  support in arm_arch_timer Xiongfeng Wang <wangxiongfeng2@huawei.com> - 2016-11-17 10:40 +0100
      Re: [PATCH v16 00/15] acpi, clocksource: add GTDT driver and GTDT  support in arm_arch_timer Fu Wei <fu.wei@linaro.org> - 2016-11-17 12:20 +0100
  Re: [PATCH v16 00/15] acpi, clocksource: add GTDT driver and GTDT  support in arm_arch_timer Daniel Lezcano <daniel.lezcano@linaro.org> - 2016-11-17 10:50 +0100

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