Re: [PATCH 4/5] clocksource: rockchip: add support for rk3399 SoC

Huang, Tao
2016-06-01T01:58:08Z

Hi Daniel:
On 2016年05月31日 22:06, Daniel Lezcano wrote:
>>
>> @@ -46,15 +48,20 @@ static inline void __iomem *rk_base(struct
>> clock_event_device *ce)
>> return rk_timer(ce)->base;
>> }
>>
>> +static inline void __iomem *rk_ctrl(struct clock_event_device *ce)
>> +{
>> + return rk_timer(ce)->base + rk_timer(ce)->ctrl;
>
> You can do a small optimization by pre-computing 'ctrl' at init time, so
> no need to do this addition each time.

I understand what you mean, please see comment below.
And even we use ctrl as pointer, we still will get addition LDR other
then ADD.
This is disassemble code before:
0: f9408021 ldr x1, [x1,#256]
4: 52800003 mov w3, #0x0
8: 91004022 add x2, x1, #0x10
c: b9000043 str w3, [x2]
This is disassemble code after change:
0: 52800003 mov w3, #0x0
4: f9408422 ldr x2, [x1,#264]
8: b9000043 str w3, [x2]
c: f9408021 ldr x1, [x1,#256]
Of course we can assume cache hit.

>
>> +}
>> +
>> static inline void rk_timer_disable(struct clock_event_device *ce)
>> {
>> - writel_relaxed(TIMER_DISABLE, rk_base(ce) + TIMER_CONTROL_REG);
>> + writel_relaxed(TIMER_DISABLE, rk_ctrl(ce));
>> }
>>
>> static inline void rk_timer_enable(struct clock_event_device *ce, u32
>> flags)
>> {
>> writel_relaxed(TIMER_ENABLE | TIMER_INT_UNMASK | flags,
>> - rk_base(ce) + TIMER_CONTROL_REG);
>> + rk_ctrl(ce));
>> }
>>
>> static void rk_timer_update_counter(unsigned long cycles,
>> @@ -179,4 +186,19 @@ out_unmap:
>> iounmap(bc_timer.base);
>> }
>>
>> -CLOCKSOURCE_OF_DECLARE(rk_timer, "rockchip,rk3288-timer", rk_timer_init);
>> +static void __init rk3288_timer_init(struct device_node *np)
>> +{
>> + bc_timer.ctrl = TIMER_CONTROL_REG3288;
>> + rk_timer_init(np);
>
> rk_timer_init(np);
> bc_timer.ctrl = bc_timer.base + TIMER_CONTROL_REG3288;

No. It's not such simple. You will access null pointer when
rk_timer_init, if we keep rk_timer_disable call in init or after
request_irq/clockevents_config_and_register and interrupt happen
immediately.

So the code maybe:
static void __init rk3288_timer_init(struct device_node *np)
{
bc_timer.base = of_iomap(np, 0);
if (!bc_timer.base) {
pr_err("Failed to get base address for '%s'\n", TIMER_NAME);
return;
}
bc_timer.ctrl = bc_timer.base + TIMER_CONTROL_REG3288;
rk_imter_init(np); // of course remove of_iomap from init.

Is this what you want?