linux-kernel - Re: [PATCH] clocksource/drivers/timer-ti-dm: Fix suspend and resume for am3 and am4

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Date:   Wed, 15 Jul 2020 21:43:47 +0300
From:   Grygorii Strashko <grygorii.strashko@...com>
To:     Tony Lindgren <tony@...mide.com>
CC:     Daniel Lezcano <daniel.lezcano@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        <linux-kernel@...r.kernel.org>, <linux-omap@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        Carlos Hernandez <ceh@...com>
Subject: Re: [PATCH] clocksource/drivers/timer-ti-dm: Fix suspend and resume
 for am3 and am4



On 15/07/2020 20:32, Tony Lindgren wrote:
> * Grygorii Strashko <grygorii.strashko@...com> [200715 10:17]:
>> On 13/07/2020 19:26, Tony Lindgren wrote:
>>> @@ -653,8 +679,8 @@ static int __init dmtimer_clocksource_init(struct device_node *np)
>>>    	dev->mask = CLOCKSOURCE_MASK(32);
>>>    	dev->flags = CLOCK_SOURCE_IS_CONTINUOUS;
>>> -	if (of_device_is_compatible(np, "ti,am33xx") ||
>>> -	    of_device_is_compatible(np, "ti,am43")) {
>>> +	/* Unlike for clockevent, legacy code sets suspend only for am4 */
>>> +	if (of_machine_is_compatible("ti,am43")) {
>>>    		dev->suspend = dmtimer_clocksource_suspend;
>>>    		dev->resume = dmtimer_clocksource_resume;
>>>    	}
>>>
>>
>> It might be better to use SOC_BUS infra here, which is available on OMAP platforms by default,
>> instead if DT. What do you think?
> 
> Well we have time_init() run very early, and some SoCs have only external
> timers. So timer-ti-dm-systimer must be initialized early. And I think
> soc_device_match() depends on soc_bus_register() that runs later at
> core_initcall().

Ah. right it's early init. I revoke my proposal then.

> 
> If you are thinking of something else, or we can use soc_device_match()
> early, sure :) But sounds like that change should be a separate patch
> then.
> 
> The reason for why we need to check for the SoC, we have the compatible
> for ti,am335x-timer already in use on am3/4 and dm814x, so we can't use
> TIMER_OF_DECLARE alone here.


-- 
Best regards,
grygorii