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From: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
To: Kieran Bingham <kieran.bingham@ideasonboard.com>, y@Mani-XPS-13-9360
Cc: kieran.bingham+renesas@ideasonboard.com,
	linux-renesas-soc@vger.kernel.org, linux-media@vger.kernel.org,
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
	"Mauro Carvalho Chehab" <mchehab@kernel.org>,
	"Laurent Pinchart" <laurent.pinchart@ideasonboard.com>,
	"Jacopo Mondi" <jacopo@jmondi.org>,
	"Niklas Söderlund" <niklas.soderlund@ragnatech.se>,
	sakari.ailus@iki.fi, "Hans Verkuil" <hverkuil@xs4all.nl>,
	"Hyun Kwon" <hyunk@xilinx.com>,
	"Rob Herring" <robh+dt@kernel.org>,
	"Jacopo Mondi" <jacopo+renesas@jmondi.org>,
	"Laurent Pinchart" <laurent.pinchart+renesas@ideasonboard.com>,
	"Niklas Söderlund" <niklas.soderlund+renesas@ragnatech.se>
Subject: Re: [PATCH v9 2/4] media: i2c: Add MAX9286 driver
Date: Thu, 14 May 2020 18:24:45 +0530	[thread overview]
Message-ID: <20200514125445.GH2877@Mani-XPS-13-9360> (raw)
In-Reply-To: <d4d0e298-b863-8c6e-c9d7-ba861a98359e@ideasonboard.com>

On Thu, May 14, 2020 at 01:27:01PM +0100, Kieran Bingham wrote:
> Hi Mani,
> 
> On 14/05/2020 12:47, Kieran Bingham wrote:
> > On 14/05/2020 11:13, Manivannan Sadhasivam wrote:
> >> Hi Kieran,
> <snip>
> 
> >>>>> +static int max9286_parse_dt(struct max9286_priv *priv)
> >>>>> +{
> >>>>> +	struct device *dev = &priv->client->dev;
> >>>>> +	struct device_node *i2c_mux;
> >>>>> +	struct device_node *node = NULL;
> >>>>> +	unsigned int i2c_mux_mask = 0;
> >>>>> +
> >>>>> +	of_node_get(dev->of_node);
> >>>>
> >>>> Why this is needed?
> >>>
> >>> Hrm .. I recall adding it to solve dt reference balancing.
> >>>
> >>> I wish I'd added a comment at the time ... as I can't recall the details
> >>> now.
> >>>
> >>
> >> I understand that it is for the refcount balancing but I certainly don't see
> >> a need for it.
> > 
> > I'll go through and try to validate this again now.
> 
> Aha, that's why:
> 
>  *	of_find_node_by_name - Find a node by its "name" property
>  *	@from:	The node to start searching from or NULL; the node
>  *		you pass will not be searched, only the next one
>  *		will. Typically, you pass what the previous call
>  *		returned. of_node_put() will be called on @from.
>  *	@name:	The name string to match against
> 
> I'll add a comment to state that it is to balance the of_node_put during
> of_find_node_by_name().
> 

Ah, right. I mostly use of_find_node_by_name() with NULL, so didn't realize
this.

And yeah, a comment would be helpful.

Thanks,
Mani

> --
> Kieran
> 
> 
> >>>>> +	i2c_mux = of_find_node_by_name(dev->of_node, "i2c-mux");
> >>>>> +	if (!i2c_mux) {
> >>>>> +		dev_err(dev, "Failed to find i2c-mux node\n");
> >>>>> +		of_node_put(dev->of_node);
> >>>>> +		return -EINVAL;
> >>>>> +	}
> >>>>> +
> >> [...]
> >>>>
> -- 
> Regards
> --
> Kieran

  reply	other threads:[~2020-05-14 12:55 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-12 15:51 [PATCH v9 0/4] MAX9286 GMSL Support (+RDACM20) Kieran Bingham
2020-05-12 15:51 ` [PATCH v9 1/4] dt-bindings: media: i2c: Add bindings for Maxim Integrated MAX9286 Kieran Bingham
2020-05-12 22:33   ` Rob Herring
2020-05-12 22:36   ` Rob Herring
2020-05-13 12:28     ` Jacopo Mondi
2020-05-12 15:51 ` [PATCH v9 2/4] media: i2c: Add MAX9286 driver Kieran Bingham
2020-05-12 17:40   ` Manivannan Sadhasivam
2020-05-14  9:53     ` Kieran Bingham
2020-05-14  9:59       ` Manivannan Sadhasivam
2020-05-14 10:05         ` Kieran Bingham
2020-05-12 18:17   ` Manivannan Sadhasivam
2020-05-14 10:02     ` Kieran Bingham
2020-05-14 10:13       ` Manivannan Sadhasivam
2020-05-14 11:47         ` Kieran Bingham
2020-05-14 11:59           ` Geert Uytterhoeven
2020-05-14 12:48             ` Manivannan Sadhasivam
2020-05-14 13:50               ` Kieran Bingham
2020-05-14 11:47         ` Kieran Bingham
2020-05-14 12:27           ` Kieran Bingham
2020-05-14 12:54             ` Manivannan Sadhasivam [this message]
2020-05-16 21:51   ` Sakari Ailus
2020-05-18 11:45     ` Kieran Bingham
2020-05-18 12:38       ` Jacopo Mondi
2020-05-18 13:09         ` Kieran Bingham
2020-05-19  8:10       ` Sakari Ailus
2020-05-19  8:55         ` Kieran Bingham
2020-05-19  9:03           ` Sakari Ailus
2020-05-20  0:50       ` Laurent Pinchart
2020-05-26  8:54         ` Sakari Ailus
2020-05-12 15:51 ` [PATCH v9 3/4] dt-bindings: media: i2c: Add bindings for IMI RDACM2x Kieran Bingham
2020-05-12 15:51 ` [PATCH v9 4/4] media: i2c: Add RDACM20 driver Kieran Bingham
2020-05-16 22:36   ` Sakari Ailus
2020-05-18  7:35     ` Jacopo Mondi

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