linux-kernel - Re: [PATCH] ACPI / scan: Add a scan handler for PRP0001

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Date:	Mon, 13 Apr 2015 19:04:14 -0700
From:	Darren Hart <dvhart@...radead.org>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	Zhang Rui <rui.zhang@...el.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ACPI / scan: Add a scan handler for PRP0001

On Sat, Apr 11, 2015 at 01:28:45AM +0200, Rafael Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> 
> If the special PRP0001 device ID is present in the given device's list
> of ACPI/PNP IDs and the device has a valid "compatible" property in
> the _DSD, it should be enumerated using the default mechanism,
> unless some scan handlers match the IDs preceding PRP0001 in the
> device's list of ACPI/PNP IDs.  In particular, no scan handlers
> matching the IDs following PRP0001 in that list should be attached
> to the device.
> 
> To make that happen, define a scan handler that will match PRP0001
> and trigger the default enumeration for the matching devices if the
> "compatible" property is present for them.
> 
> Since that requires the check for platform_id and device->handler
> to be removed from acpi_default_enumeration(), move the fallback
> invocation of acpi_default_enumeration() to acpi_bus_attach()
> (after it's checked if there's a matching ACPI driver for the
> device), which is a better place to call it, and do the platform_id
> check in there too (device->handler is guaranteed to be unset at
> the point where the function is looking for a matching ACPI driver).
> 
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> ---
>  drivers/acpi/scan.c |   34 +++++++++++++++++++++++++++++-----
>  1 file changed, 29 insertions(+), 5 deletions(-)
> 
> Index: linux-pm/drivers/acpi/scan.c
> ===================================================================
> --- linux-pm.orig/drivers/acpi/scan.c
> +++ linux-pm/drivers/acpi/scan.c
> @@ -2390,9 +2390,6 @@ static void acpi_default_enumeration(str
>  	struct list_head resource_list;
>  	bool is_spi_i2c_slave = false;
>  
> -	if (!device->pnp.type.platform_id || device->handler)
> -		return;
> -
>  	/*
>  	 * Do not enemerate SPI/I2C slaves as they will be enuerated by their
>  	 * respective parents.
> @@ -2405,6 +2402,30 @@ static void acpi_default_enumeration(str
>  		acpi_create_platform_device(device);
>  }
>  
> +static const struct acpi_device_id generic_device_ids[] = {
> +	{"PRP0001", },
> +	{"", },
> +};
> +
> +static int acpi_generic_device_attach(struct acpi_device *adev,
> +				      const struct acpi_device_id *not_used)
> +{
> +	/*
> +	 * Since PRP0001 is the only ID handled here, the test below can be
> +	 * unconditional.
> +	 */
> +	if (adev->data.of_compatible) {
> +		acpi_default_enumeration(adev);
> +		return 1;
> +	}

Would a warning be appropriate here? PRP0001 should only appear when paired with
a DSD of GUID Device Properties with a "compatible" entry. If not, it's an
error, correct? I believe we warn on similarly malformed AML?

Otherwise,

Acked-by: Darren Hart <dvhart@...ux.intel.com>

-- 
Darren Hart
Intel Open Source Technology Center
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