linux-kernel - Re: [RFC PATCH for Juno 1/2] net: smsc911x add support for probing from ACPI

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Message-ID: <20140901170447.GF608@arm.com>
Date:	Mon, 1 Sep 2014 18:04:47 +0100
From:	Catalin Marinas <catalin.marinas@....com>
To:	Hanjun Guo <hanjun.guo@...aro.org>
Cc:	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Mark Rutland <Mark.Rutland@....com>,
	Olof Johansson <olof@...om.net>,
	"grant.likely@...aro.org" <grant.likely@...aro.org>,
	"graeme.gregory@...aro.org" <graeme.gregory@...aro.org>,
	Arnd Bergmann <arnd@...db.de>,
	Sudeep Holla <Sudeep.Holla@....com>,
	Will Deacon <Will.Deacon@....com>,
	Jason Cooper <jason@...edaemon.net>,
	Marc Zyngier <Marc.Zyngier@....com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Mark Brown <broonie@...nel.org>, Rob Herring <robh@...nel.org>,
	Robert Richter <rric@...nel.org>,
	Lv Zheng <lv.zheng@...el.com>,
	Robert Moore <robert.moore@...el.com>,
	Lorenzo Pieralisi <Lorenzo.Pieralisi@....com>,
	Liviu Dudau <Liviu.Dudau@....com>,
	Randy Dunlap <rdunlap@...radead.org>,
	Charles Garcia-Tobin <Charles.Garcia-Tobin@....com>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linaro-acpi@...ts.linaro.org" <linaro-acpi@...ts.linaro.org>
Subject: Re: [RFC PATCH for Juno 1/2] net: smsc911x add support for probing
 from ACPI

On Mon, Sep 01, 2014 at 04:06:00PM +0100, Hanjun Guo wrote:
> +#ifdef CONFIG_ACPI
> +/* Configure some sensible defaults for ACPI mode */
> +static int smsc911x_probe_config_acpi(struct smsc911x_platform_config *config,
> +				    acpi_handle *ahandle)
> +{
> +	if (!ahandle)
> +		return -ENOSYS;
> +
> +	config->phy_interface = PHY_INTERFACE_MODE_MII;
> +
> +	config->flags |= SMSC911X_USE_32BIT;
> +
> +	config->irq_polarity = SMSC911X_IRQ_POLARITY_ACTIVE_HIGH;
> +
> +	config->irq_type = SMSC911X_IRQ_TYPE_PUSH_PULL;
> +
> +	return 0;
> +}
> +#else

I don't like this and it shows issues we have with ACPI on certain ARM
platforms. You hard-code these values to match the Juno platform. What
if we get another SoC which has different configuration here? For DT, we
have the smsc911x_probe_config_dt() which reads the relevant information
from DT. I think this kind of configuration would be more suitable as
_DSD properties and sharing the similar names with DT (but we go back to
the question about who's in charge of the _DSD properties).

>  static int smsc911x_drv_probe(struct platform_device *pdev)
>  {
>  	struct device_node *np = pdev->dev.of_node;
> +	acpi_handle *ahandle = ACPI_HANDLE(&pdev->dev);
>  	struct net_device *dev;
>  	struct smsc911x_data *pdata;
>  	struct smsc911x_platform_config *config = dev_get_platdata(&pdev->dev);
> @@ -2436,6 +2464,9 @@ static int smsc911x_drv_probe(struct platform_device *pdev)
>  	}
>  
>  	retval = smsc911x_probe_config_dt(&pdata->config, np);
> +	if (retval)
> +		retval = smsc911x_probe_config_acpi(&pdata->config, ahandle);
> +

In most of the ACPI patches so far we check for ACPI first with DT as a
fall-back if ACPI is not enabled. This changes here. I would prefer
something which probes only ACPI if the ACPI is enabled (run-time, not
config) otherwise DT only. E.g.

-- 
Catalin
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