linux-kernel - Re: [PATCH v5 2/5] acpi: Store CRC-32 hash of the _PLD in struct acpi

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Message-ID: <20220130164126.GA2942650@roeck-us.net>
Date:   Sun, 30 Jan 2022 08:41:26 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Heikki Krogerus <heikki.krogerus@...ux.intel.com>
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Prashant Malani <pmalani@...omium.org>,
        linux-acpi@...r.kernel.org, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 2/5] acpi: Store CRC-32 hash of the _PLD in struct
 acpi_device

On Thu, Dec 23, 2021 at 11:16:17AM +0300, Heikki Krogerus wrote:
> Storing CRC-32 hash of the Physical Location of Device
> object (_PLD) with devices that have it. The hash is stored
> to a new struct acpi_device member "pld_crc".
> 
> The hash makes it easier to find devices that share a
> location, as there is no need to evaluate the entire object
> every time. Knowledge about devices that share a location
> can be used in device drivers that need to know the
> connections to other components inside a system. USB3 ports
> will for example always share their location with a USB2
> port.
> 
> Signed-off-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>

Building ia64:tinyconfig ... failed

ia64-linux-ld: drivers/acpi/scan.o: in function `__acpi_device_add':
scan.c:(.text+0x27e2): undefined reference to `crc32_le'

ACPI now depends on CRC32.

#regzbot introduced: 882c982dada4d5

Guenter

> ---
>  drivers/acpi/scan.c     | 16 ++++++++++++++++
>  include/acpi/acpi_bus.h |  1 +
>  2 files changed, 17 insertions(+)
> 
> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> index 7ff55a197a583..113414c46b713 100644
> --- a/drivers/acpi/scan.c
> +++ b/drivers/acpi/scan.c
> @@ -19,6 +19,7 @@
>  #include <linux/dma-map-ops.h>
>  #include <linux/platform_data/x86/apple.h>
>  #include <linux/pgtable.h>
> +#include <linux/crc32.h>
>  
>  #include "internal.h"
>  
> @@ -667,6 +668,19 @@ static int acpi_tie_acpi_dev(struct acpi_device *adev)
>  	return 0;
>  }
>  
> +static void acpi_store_pld_crc(struct acpi_device *adev)
> +{
> +	struct acpi_pld_info *pld;
> +	acpi_status status;
> +
> +	status = acpi_get_physical_device_location(adev->handle, &pld);
> +	if (ACPI_FAILURE(status))
> +		return;
> +
> +	adev->pld_crc = crc32(~0, pld, sizeof(*pld));
> +	ACPI_FREE(pld);
> +}
> +
>  static int __acpi_device_add(struct acpi_device *device,
>  			     void (*release)(struct device *))
>  {
> @@ -725,6 +739,8 @@ static int __acpi_device_add(struct acpi_device *device,
>  	if (device->wakeup.flags.valid)
>  		list_add_tail(&device->wakeup_list, &acpi_wakeup_device_list);
>  
> +	acpi_store_pld_crc(device);
> +
>  	mutex_unlock(&acpi_device_lock);
>  
>  	if (device->parent)
> diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
> index 8e87ead2af341..f8c945418df23 100644
> --- a/include/acpi/acpi_bus.h
> +++ b/include/acpi/acpi_bus.h
> @@ -360,6 +360,7 @@ struct acpi_gpio_mapping;
>  
>  /* Device */
>  struct acpi_device {
> +	u32 pld_crc;
>  	int device_type;
>  	acpi_handle handle;		/* no handle for fixed hardware */
>  	struct fwnode_handle fwnode;