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Date:   Fri, 11 Aug 2023 13:39:24 -0600
From:   Rob Herring <robh@kernel.org>
To:     Anup Patel <apatel@ventanamicro.com>
Cc:     Palmer Dabbelt <palmer@dabbelt.com>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Marc Zyngier <maz@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Frank Rowand <frowand.list@gmail.com>,
        Conor Dooley <conor+dt@kernel.org>,
        Atish Patra <atishp@atishpatra.org>,
        Andrew Jones <ajones@ventanamicro.com>,
        Sunil V L <sunilvl@ventanamicro.com>,
        Saravana Kannan <saravanak@google.com>,
        Anup Patel <anup@brainfault.org>,
        linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
        devicetree@vger.kernel.org
Subject: Re: [PATCH v7 02/15] of: property: Add fw_devlink support for
 msi-parent
Message-ID: <20230811193924.GA3997669-robh@kernel.org>
References: <20230802150018.327079-1-apatel@ventanamicro.com>
 <20230802150018.327079-3-apatel@ventanamicro.com>
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On Wed, Aug 02, 2023 at 08:30:05PM +0530, Anup Patel wrote:
> This allows fw_devlink to create device links between consumers of
> a MSI and the supplier of the MSI.
> 
> Signed-off-by: Anup Patel <apatel@ventanamicro.com>
> ---
>  drivers/of/property.c | 32 ++++++++++++++++++++++++++++++++
>  1 file changed, 32 insertions(+)
> 
> diff --git a/drivers/of/property.c b/drivers/of/property.c
> index ddc75cd50825..bc20535deed7 100644
> --- a/drivers/of/property.c
> +++ b/drivers/of/property.c
> @@ -1325,6 +1325,37 @@ static struct device_node *parse_interrupts(struct device_node *np,
>  	return of_irq_parse_one(np, index, &sup_args) ? NULL : sup_args.np;
>  }
>  
> +static struct device_node *parse_msi_parent(struct device_node *np,
> +					    const char *prop_name, int index)
> +{
> +	struct of_phandle_args sup_args;
> +	struct device_node *msi_np;
> +
> +	if (IS_ENABLED(CONFIG_SPARC))
> +		return NULL;
> +
> +	if (strcmp(prop_name, "msi-parent"))
> +		return NULL;
> +
> +	msi_np = of_parse_phandle(np, prop_name, 0);
> +	if (msi_np) {
> +		if (!of_property_read_bool(msi_np, "#msi-cells")) {

Use of_property_present() to check presence.

However, this check is wrong. #msi-cells is optional and assumed to be 0 
if not present. There's another flavor of of_parse_phandle_with_args() 
that allows specifying a default cell count, so I think you can get rid 
of all this checking.

> +			if (index) {
> +				of_node_put(msi_np);
> +				return NULL;
> +			}
> +			return msi_np;
> +		}
> +		of_node_put(msi_np);
> +	}
> +
> +	if (of_parse_phandle_with_args(np, prop_name, "#msi-cells", index,
> +				       &sup_args))
> +		return NULL;
> +
> +	return sup_args.np;
> +}
> +
>  static const struct supplier_bindings of_supplier_bindings[] = {
>  	{ .parse_prop = parse_clocks, },
>  	{ .parse_prop = parse_interconnects, },
> @@ -1359,6 +1390,7 @@ static const struct supplier_bindings of_supplier_bindings[] = {
>  	{ .parse_prop = parse_regulators, },
>  	{ .parse_prop = parse_gpio, },
>  	{ .parse_prop = parse_gpios, },
> +	{ .parse_prop = parse_msi_parent, },
>  	{}
>  };
>  
> -- 
> 2.34.1
>