linux-kernel - Re: [PATCH v2 1/8] i2c-mux: add common core data for every mux instance

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Message-ID: <56F3B86E.4050002@mentor.com>
Date:	Thu, 24 Mar 2016 11:50:38 +0200
From:	Vladimir Zapolskiy <vladimir_zapolskiy@...tor.com>
To:	Peter Rosin <peda@...ator.liu.se>
CC:	Wolfram Sang <wsa@...-dreams.de>, Peter Rosin <peda@...ntia.se>,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Peter Korsgaard <peter.korsgaard@...co.com>,
	Guenter Roeck <linux@...ck-us.net>,
	Jonathan Cameron <jic23@...nel.org>,
	Hartmut Knaack <knaack.h@....de>,
	Lars-Peter Clausen <lars@...afoo.de>,
	Peter Meerwald <pmeerw@...erw.net>,
	Antti Palosaari <crope@....fi>,
	Mauro Carvalho Chehab <mchehab@....samsung.com>,
	Frank Rowand <frowand.list@...il.com>,
	Grant Likely <grant.likely@...aro.org>,
	Adriana Reus <adriana.reus@...el.com>,
	Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
	Krzysztof Kozlowski <k.kozlowski@...sung.com>,
	Hans Verkuil <hans.verkuil@...co.com>,
	Nicholas Mc Guire <hofrat@...dl.org>,
	Olli Salonen <olli.salonen@....fi>,
	<linux-i2c@...r.kernel.org>, <devicetree@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <linux-iio@...r.kernel.org>,
	<linux-media@...r.kernel.org>
Subject: Re: [PATCH v2 1/8] i2c-mux: add common core data for every mux
 instance

Hi Peter,

On 05.01.2016 17:57, Peter Rosin wrote:
> From: Peter Rosin <peda@...ntia.se>
> 
> The initial core mux structure starts off small with only the parent
> adapter pointer, which all muxes have, and a priv pointer for mux
> driver private data.
> 
> Add i2c_mux_alloc function to unify the creation of a mux.
> 
> Where appropriate, pass around the mux core structure instead of the
> parent adapter or the driver private data.
> 
> Remove the parent adapter pointer from the driver private data for all
> mux drivers.
> 
> Signed-off-by: Peter Rosin <peda@...ntia.se>

is it still under review? If yes, please find one question from me below :)

[snip]

> @@ -196,21 +195,21 @@ static int i2c_arbitrator_probe(struct platform_device *pdev)
>  		dev_err(dev, "Cannot parse i2c-parent\n");
>  		return -EINVAL;
>  	}
> -	arb->parent = of_get_i2c_adapter_by_node(parent_np);
> +	muxc->parent = of_find_i2c_adapter_by_node(parent_np);

why do you prefer here to use "unlocked" version of API?

Foe example would it be safe/possible to unload an I2C bus device driver
module or unbind I2C device itself in runtime?

>  	of_node_put(parent_np);
> -	if (!arb->parent) {
> +	if (!muxc->parent) {
>  		dev_err(dev, "Cannot find parent bus\n");
>  		return -EPROBE_DEFER;
>  	}
>  
>  	/* Actually add the mux adapter */
> -	arb->child = i2c_add_mux_adapter(arb->parent, dev, arb, 0, 0, 0,
> +	arb->child = i2c_add_mux_adapter(muxc, dev, arb, 0, 0, 0,
>  					 i2c_arbitrator_select,
>  					 i2c_arbitrator_deselect);
>  	if (!arb->child) {
>  		dev_err(dev, "Failed to add adapter\n");
>  		ret = -ENODEV;
> -		i2c_put_adapter(arb->parent);
> +		i2c_put_adapter(muxc->parent);
>  	}
>  
>  	return ret;

--
With best wishes,
Vladimir