linux-kernel - Re: [PATCH 04/10] rtc: at91rm9200: use of_platform

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Message-ID: <20191218165831.GO695889@piout.net>
Date:   Wed, 18 Dec 2019 17:58:31 +0100
From:   Alexandre Belloni <alexandre.belloni@...tlin.com>
To:     Eugen.Hristev@...rochip.com
Cc:     jic23@...nel.org, robh+dt@...nel.org, Nicolas.Ferre@...rochip.com,
        linux-iio@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-rtc@...r.kernel.org, a.zummo@...ertech.it,
        Ludovic.Desroches@...rochip.com
Subject: Re: [PATCH 04/10] rtc: at91rm9200: use of_platform_populate as
 return value

On 18/12/2019 16:52:21+0000, Eugen.Hristev@...rochip.com wrote:
> 
> 
> On 18.12.2019 18:43, Alexandre Belloni wrote:
> 
> > Hi,
> > 
> > On 18/12/2019 16:24:00+0000, Eugen.Hristev@...rochip.com wrote:
> >> From: Eugen Hristev <eugen.hristev@...rochip.com>
> >>
> >> This allows the RTC node to have child nodes in DT.
> >> This allows subnodes to be probed.
> >>
> >> Signed-off-by: Eugen Hristev <eugen.hristev@...rochip.com>
> >> ---
> >>   drivers/rtc/rtc-at91rm9200.c | 2 +-
> >>   1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/rtc/rtc-at91rm9200.c b/drivers/rtc/rtc-at91rm9200.c
> >> index 3b833e0..f1b5b3d 100644
> >> --- a/drivers/rtc/rtc-at91rm9200.c
> >> +++ b/drivers/rtc/rtc-at91rm9200.c
> >> @@ -421,7 +421,7 @@ static int __init at91_rtc_probe(struct platform_device *pdev)
> >>        at91_rtc_write_ier(AT91_RTC_SECEV);
> >>
> >>        dev_info(&pdev->dev, "AT91 Real Time Clock driver.\n");
> >> -     return 0;
> >> +     return of_platform_populate(pdev->dev.of_node, NULL, NULL, &pdev->dev);
> >>
> > 
> > You can avoid the DT binding change and DT parsing by using
> > platform_add_device here. I don't think there is any point describing
> > the trigger as a child node (a watchdog functionality wouldn't be
> > described for example).
> > 
> 
> Hi,
> 
> It's needed because the ADC needs a link to the trigger device. This is 
> a hardware link inside the SoC, so I thought the best way is to describe 
> this hardware is in the Device Tree.
> Otherwise the ADC node is unaware of the RTC triggering possibility.
> If we just assign the RTC trigger device to the ADC through the sysfs, 
> the ADC cannot distinguish between the RTC trigger and other various 
> triggers which can be attached.
> 

I'm not sure this links is required but I will let Jonathan review. Even
if it is needed, you can still use the rtc node to describe that link.

-- 
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com