linux-kernel - Re: [PATCH] rtc: pcf85363: Allow to wake up system without IRQ

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Date:   Thu, 17 Aug 2023 11:02:43 +0200
From:   Mike Looijmans <mike.looijmans@...ic.nl>
To:     Alexandre Belloni <alexandre.belloni@...tlin.com>
CC:     linux-rtc@...r.kernel.org, Alessandro Zummo <a.zummo@...ertech.it>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] rtc: pcf85363: Allow to wake up system without IRQ


Met vriendelijke groet / kind regards,

Mike Looijmans
System Expert


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T: +31 (0) 499 33 69 69
E: mike.looijmans@...ic.nl
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On 17-08-2023 10:17, Alexandre Belloni wrote:
> On 17/08/2023 07:42:25+0200, Mike Looijmans wrote:
>> On 16-08-2023 23:40, Alexandre Belloni wrote:
>>> Hello Mike,
>>>
>>> Sorry for the very late review, there is a small change that is needed:
>>
>> Better late than never
>>
>>>
>>> On 02/05/2023 07:54:58+0200, Mike Looijmans wrote:
>>>> When wakeup-source is set in the devicetree, set up the device for
>>>> using the output as interrupt instead of clock. This is similar to
>>>> how other RTC devices handle this.
>>>>
>>>> This allows the clock chip to turn on the board when wired to do
>>>> so in hardware.
>>>>
>>>> Signed-off-by: Mike Looijmans <mike.looijmans@...ic.nl>
>>>>
>>>> ---
>>>>
>>>>    drivers/rtc/rtc-pcf85363.c | 17 ++++++++++-------
>>>>    1 file changed, 10 insertions(+), 7 deletions(-)
>>>>
>>>> diff --git a/drivers/rtc/rtc-pcf85363.c b/drivers/rtc/rtc-pcf85363.c
>>>> index 8958eadf1c3e..b1543bcdc530 100644
>>>> --- a/drivers/rtc/rtc-pcf85363.c
>>>> +++ b/drivers/rtc/rtc-pcf85363.c
>>>> @@ -434,23 +434,26 @@ static int pcf85363_probe(struct i2c_client *client)
>>>>    	pcf85363->rtc->range_max = RTC_TIMESTAMP_END_2099;
>>>>    	clear_bit(RTC_FEATURE_ALARM, pcf85363->rtc->features);
>>>> +	if (client->irq > 0 || device_property_read_bool(&client->dev,
>>>> +							 "wakeup-source")) {
>>>> +		regmap_write(pcf85363->regmap, CTRL_FLAGS, 0);
>>>> +		regmap_update_bits(pcf85363->regmap, CTRL_PIN_IO,
>>>> +				   PIN_IO_INTA_OUT, PIN_IO_INTAPM);
>>>> +		device_init_wakeup(&client->dev, true);
>>>> +		set_bit(RTC_FEATURE_ALARM, pcf85363->rtc->features);
>>>
>>> This should not be done when devm_request_threaded_irq fails.
>>
>> Yeah, easiest would be to just clear the feature flag when that happens.
> 
> My comment was also for device_init_wakeup(&client->dev, true);. I think
> the easiest would be to move this block later on and set client->irq to
> 0 when devm_request_threaded_irq fails.
> 

Ah, clear. That also properly handles things when IRQ fails but wakeup-source 
was present. In table form:

IRQ   wakeup-source   Call "device_init_wakeup" etc.
N/A   No              No
N/A   Yes             Yes
OK    No              Yes
OK    Yes             Yes
FAIL  No              No
FAIL  Yes             Yes

We still have to program the registers before registering the IRQ I think.