Date: Fri, 7 Aug 2015 12:43:20 +0200
From: Robert Richter <robert.richter@caviumnetworks.com>
To: Tomasz Nowicki <tomasz.nowicki@linaro.org>
CC: David Daney <ddaney.cavm@gmail.com>, <linux-kernel@vger.kernel.org>,
        <netdev@vger.kernel.org>, "David S. Miller" <davem@davemloft.net>,
        <linux-mips@linux-mips.org>, Sunil Goutham <sgoutham@cavium.com>,
        <linux-arm-kernel@lists.infradead.org>, <linux-acpi@vger.kernel.org>,
        David Daney <david.daney@cavium.com>
Subject: Re: [PATCH 2/2] net, thunder, bgx: Add support for ACPI binding.
Message-ID: <20150807104320.GQ1820@rric.localhost>
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On 07.08.15 10:09:04, Tomasz Nowicki wrote:
> On 07.08.2015 02:33, David Daney wrote:

...

> >+#else
> >+
> >+static int bgx_init_acpi_phy(struct bgx *bgx)
> >+{
> >+	return -ENODEV;
> >+}
> >+
> >+#endif /* CONFIG_ACPI */
> >+
> >  #if IS_ENABLED(CONFIG_OF_MDIO)
> >
> >  static int bgx_init_of_phy(struct bgx *bgx)
> >@@ -882,7 +1010,12 @@ static int bgx_init_of_phy(struct bgx *bgx)
> >
> >  static int bgx_init_phy(struct bgx *bgx)
> >  {
> >-	return bgx_init_of_phy(bgx);
> >+	int err = bgx_init_of_phy(bgx);
> >+
> >+	if (err != -ENODEV)
> >+		return err;
> >+
> >+	return bgx_init_acpi_phy(bgx);
> >  }
> >
> 
> If kernel can work with DT and ACPI (both compiled in), it should take only
> one path instead of probing DT and ACPI sequentially. How about:
> 
> @@ -902,10 +925,9 @@ static int bgx_probe(struct pci_dev *pdev, const struct
> pci_device_id *ent)
>  	bgx_vnic[bgx->bgx_id] = bgx;
>  	bgx_get_qlm_mode(bgx);
> 
> -	snprintf(bgx_sel, 5, "bgx%d", bgx->bgx_id);
> -	np = of_find_node_by_name(NULL, bgx_sel);
> -	if (np)
> -		bgx_init_of(bgx, np);
> +	err = acpi_disabled ? bgx_init_of_phy(bgx) : bgx_init_acpi_phy(bgx);
> +	if (err)
> +		goto err_enable;
> 
>  	bgx_init_hw(bgx);

I would not pollute bgx_probe() with acpi and dt specifics, and instead
keep bgx_init_phy(). The typical design pattern for this is:

static int bgx_init_phy(struct bgx *bgx)
{
#ifdef CONFIG_ACPI
        if (!acpi_disabled)
                return bgx_init_acpi_phy(bgx);
#endif
        return bgx_init_of_phy(bgx);
}

This adds acpi runtime detection (acpi=no), does not call dt code in
case of acpi, and saves the #else for bgx_init_acpi_phy().

-Robert
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