Hi Mark,

On 19 November 2016 at 04:20, Mark Rutland [off-list ref] wrote:

On Wed, Nov 16, 2016 at 09:49:07PM +0800, fu.wei at linaro.org wrote:

quoted

From: Fu Wei <redacted>

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 <redacted>
---
 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.

quoted

+     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?

Yes, that is a good idea, but I need to find a way to get the number of
GT block in GTDT, then allocate a  struct arch_timer_mem array for all GT block

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

I don't see any doc says : there is only one memory-mapped timer
in a soc.
Maybe we have more than one GT block in GTDT or
(in another word) we may have more than one memory-mapped
timer in a soc, right ??

Please correct me, If I miss something.

quoted

+             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.

-- 
Best regards,

Fu Wei
Software Engineer
Red Hat