linux-kernel - RE: [PATCH v2] ACPI / device_sysfs: change

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Message-ID: <94F2FBAB4432B54E8AACC7DFDE6C92E3B958C7AE@ORSMSX110.amr.corp.intel.com>
Date:   Fri, 3 May 2019 19:54:57 +0000
From:   "Moore, Robert" <robert.moore@...el.com>
To:     Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>,
        "alsa-devel@...a-project.org" <alsa-devel@...a-project.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "tiwai@...e.de" <tiwai@...e.de>,
        "broonie@...nel.org" <broonie@...nel.org>,
        "vkoul@...nel.org" <vkoul@...nel.org>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "liam.r.girdwood@...ux.intel.com" <liam.r.girdwood@...ux.intel.com>,
        "jank@...ence.com" <jank@...ence.com>,
        "joe@...ches.com" <joe@...ches.com>,
        "srinivas.kandagatla@...aro.org" <srinivas.kandagatla@...aro.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>,
        "Schmauss, Erik" <erik.schmauss@...el.com>,
        "open list:ACPI" <linux-acpi@...r.kernel.org>,
        "open list:ACPI COMPONENT ARCHITECTURE (ACPICA)" <devel@...ica.org>
Subject: RE: [PATCH v2] ACPI / device_sysfs: change _ADR representation to
 64 bits



> -----Original Message-----
> From: Pierre-Louis Bossart [mailto:pierre-louis.bossart@...ux.intel.com]
> Sent: Wednesday, May 1, 2019 5:53 AM
> To: alsa-devel@...a-project.org
> Cc: linux-kernel@...r.kernel.org; tiwai@...e.de; broonie@...nel.org;
> vkoul@...nel.org; gregkh@...uxfoundation.org;
> liam.r.girdwood@...ux.intel.com; jank@...ence.com; joe@...ches.com;
> srinivas.kandagatla@...aro.org; Pierre-Louis Bossart <pierre-
> louis.bossart@...ux.intel.com>; Rafael J. Wysocki <rjw@...ysocki.net>;
> Len Brown <lenb@...nel.org>; Moore, Robert <robert.moore@...el.com>;
> Schmauss, Erik <erik.schmauss@...el.com>; open list:ACPI <linux-
> acpi@...r.kernel.org>; open list:ACPI COMPONENT ARCHITECTURE (ACPICA)
> <devel@...ica.org>
> Subject: [PATCH v2] ACPI / device_sysfs: change _ADR representation to
> 64 bits
> 
> Standards such as the MIPI DisCo for SoundWire 1.0 specification assume
> the _ADR field is 64 bits.
> 
> _ADR is defined as an "Integer" represented as 64 bits since ACPI 2.0
> released in 2002. The low levels already use _ADR as 64 bits, e.g. in
> struct acpi_device_info.
> 
[Moore, Robert] 

Just to be precise: since acpi 2.0 the integer width is either 32 bits or 64 bits, depending on the version number of the DSDT (1-->32, 2 or greater --> 64).


> This patch bumps the representation used for sysfs to 64 bits. To avoid
> any compatibility/ABI issues, the printf format is only extended to 16
> characters when the actual _ADR value exceeds the 32 bit maximum.
> 
> Example with a SoundWire device, the results show the complete vendorID
> and linkID which were omitted before:
> 
> Before:
> $ more /sys/bus/acpi/devices/device\:38/adr
> 0x5d070000
> After:
> $ more /sys/bus/acpi/devices/device\:38/adr
> 0x000010025d070000
> 
> Signed-off-by: Pierre-Louis Bossart <pierre-
> louis.bossart@...ux.intel.com>
> ---
> v2: only use 64 bits when required to avoid compatibility issues
> (feedback from Vinod and Rafael)
> 
>  drivers/acpi/device_sysfs.c | 6 ++++--
>  include/acpi/acpi_bus.h     | 2 +-
>  2 files changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/acpi/device_sysfs.c b/drivers/acpi/device_sysfs.c
> index 8940054d6250..7dda0ee05cd1 100644
> --- a/drivers/acpi/device_sysfs.c
> +++ b/drivers/acpi/device_sysfs.c
> @@ -428,8 +428,10 @@ static ssize_t acpi_device_adr_show(struct device
> *dev,  {
>  	struct acpi_device *acpi_dev = to_acpi_device(dev);
> 
> -	return sprintf(buf, "0x%08x\n",
> -		       (unsigned int)(acpi_dev->pnp.bus_address));
> +	if (acpi_dev->pnp.bus_address > 0xFFFFFFFF)
> +		return sprintf(buf, "0x%016llx\n", acpi_dev-
> >pnp.bus_address);
> +	else
> +		return sprintf(buf, "0x%08llx\n", acpi_dev->pnp.bus_address);
>  }
>  static DEVICE_ATTR(adr, 0444, acpi_device_adr_show, NULL);
> 
> diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h index
> f7981751ac77..9075e28ea60a 100644
> --- a/include/acpi/acpi_bus.h
> +++ b/include/acpi/acpi_bus.h
> @@ -230,7 +230,7 @@ struct acpi_device_dir {
>  /* Plug and Play */
> 
>  typedef char acpi_bus_id[8];
> -typedef unsigned long acpi_bus_address;
> +typedef u64 acpi_bus_address;
>  typedef char acpi_device_name[40];
>  typedef char acpi_device_class[20];
> 
> --
> 2.17.1