[PATCH] clocksource: imx-tpm: Wait for CnV write to take effect

[Daniel Lezcano]

On 11/10/2023 12:13, Jacky Bai wrote:
>> Subject: Re: [PATCH] clocksource: imx-tpm: Wait for CnV write to take effect

[ ... ]

>>>>>     static int tpm_set_next_event(unsigned long delta,
>>>>>                                    struct clock_event_device *evt)
>>>>>     {
>>>>> - unsigned long next, now;
>>>>> + unsigned long next, prev, now;
>>>>>
>>>>> - next = tpm_read_counter();
>>>>> - next += delta;
>>>>> + prev = tpm_read_counter();
>>>>> + next = prev + delta;
>>>>>            writel(next, timer_base + TPM_C0V);
>>>>>            now = tpm_read_counter();
>>>>>
>>>>> + /*
>>>>> +  * Need to wait CNT increase at least 1 cycle to make sure
>>>>> +  * the C0V has been updated into HW.
>>>>> +  */
>>>>> + if ((next & 0xffffffff) != readl(timer_base + TPM_C0V))
>>>>
>>>> Why do you use a mask for 'next' ?
>>>>
>>>
>>> 'unsigned long' is 64 bit on arm64 platform, while the register is
>>> 32bit, so the upper 32bit cleared before comparing.
>>
>> But next is unsigned long and readl returns a long, no ?
> 
> 'next' upper 32bit may not be '0's.

Is it possible to have 'next' greater than INT_MAX?


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