linux-kernel - Re: [PATCH v1 2/2] of: Let of_for_each_phandle fallback to non-negative cell

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Date:   Mon, 2 Sep 2019 15:26:39 +0100
From:   Rob Herring <robh@...nel.org>
To:     Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>
Cc:     Frank Rowand <frowand.list@...il.com>, devicetree@...r.kernel.org,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        linux-mediatek@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, kernel@...gutronix.de,
        Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        Joerg Roedel <joro@...tes.org>,
        Matthias Brugger <matthias.bgg@...il.com>
Subject: Re: [PATCH v1 2/2] of: Let of_for_each_phandle fallback to
 non-negative cell_count

On Sat, Aug 24, 2019 at 03:28:46PM +0200, Uwe Kleine-König wrote:
> Referencing device tree nodes from a property allows to pass arguments.
> This is for example used for referencing gpios. This looks as follows:
> 
> 	gpio_ctrl: gpio-controller {
> 		#gpio-cells = <2>
> 		...
> 	}
> 
> 	someothernode {
> 		gpios = <&gpio_ctrl 5 0 &gpio_ctrl 3 0>;
> 		...
> 	}
> 
> To know the number of arguments this must be either fixed, or the
> referenced node is checked for a $cells_name (here: "#gpio-cells")
> property and with this information the start of the second reference can
> be determined.
> 
> Currently regulators are referenced with no additional arguments. To
> allow some optional arguments without having to change all referenced
> nodes this change introduces a way to specify a default cell_count. So
> when a phandle is parsed we check for the $cells_name property and use
> it as before if present. If it is not present we fall back to
> cells_count if non-negative and only fail if cells_count is smaller than
> zero.
> 
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
> ---
>  drivers/of/base.c | 25 +++++++++++++++++--------
>  1 file changed, 17 insertions(+), 8 deletions(-)

Looks fine to me. I can apply with an ack from the iommu folks on patch 
1.

Rob