linux-kernel - Re: [PATCH] pwm: rz-mtu3: Share parent device node to MTU3 PWM

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Message-ID: <b041fde6-afea-4233-b00b-4e8cbb294c4a@kernel.org>
Date: Tue, 21 Oct 2025 12:47:52 +0200
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Uwe Kleine-König <ukleinek@...nel.org>,
 Martyn Welch <martyn.welch@...labora.com>
Cc: kernel@...labora.com, Sebastian Reichel
 <sebastian.reichel@...labora.com>, linux-pwm@...r.kernel.org,
 linux-kernel@...r.kernel.org, Rob Herring <robh@...nel.org>,
 Saravana Kannan <saravanak@...gle.com>, devicetree@...r.kernel.org
Subject: Re: [PATCH] pwm: rz-mtu3: Share parent device node to MTU3 PWM

On 21/10/2025 12:19, Uwe Kleine-König wrote:
>> diff --git a/drivers/pwm/pwm-rz-mtu3.c b/drivers/pwm/pwm-rz-mtu3.c
>> index ab39bd37edafc..5825875fa0128 100644
>> --- a/drivers/pwm/pwm-rz-mtu3.c
>> +++ b/drivers/pwm/pwm-rz-mtu3.c
>> @@ -523,6 +523,12 @@ static int rz_mtu3_pwm_probe(struct platform_device *pdev)
>>  	if (ret < 0)
>>  		return ret;
>>  
>> +	/*
>> +	 * There is only one DT node, get it from the parent MFD device, so
>> +	 * that the PWM channels can be referenced via phandles
>> +	 */
>> +	dev->of_node = dev->parent->of_node;
>> +
> 
> I (very quickly) talked to Krzysztof about this. He said that
> of_node_get() should probably be used here. I wonder if
> device_add_of_node() is the right function to use (which uses
> of_node_get(), also handles fwnode and implements some safeguards).


I am not so sure about device_add_of_node(). You do not need to
get_device(), because reference is already hold. Although setting
dev->fwnode might make sense... But, not that important I think, works
with me.


Best regards,
Krzysztof