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Re: [PATCH 2/2] arm/virt/acpi: remove _ADR from devices identified by _H

From: Guoheyi
Subject: Re: [PATCH 2/2] arm/virt/acpi: remove _ADR from devices identified by _HID
Date: Mon, 6 Jan 2020 10:10:24 +0800
User-agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2

在 2020/1/5 20:53, Michael S. Tsirkin 写道:
On Sun, Jan 05, 2020 at 07:34:01AM -0500, Michael S. Tsirkin wrote:
On Thu, Dec 19, 2019 at 02:47:59PM +0800, Heyi Guo wrote:
According to ACPI spec, _ADR should be used for device which is on a
bus that has a standard enumeration algorithm. It does not make sense
to have a _ADR object for devices which already have _HID and will be
enumerated by OSPM.

Signed-off-by: Heyi Guo <address@hidden>
Are you sure? I would think this depends on the ID and the device
really. E.g. PCI devices all are expected to have _ADR and some of them
have a _HID.

To clarify I am not commenting on patches.
The spec says this:
        6.1.5 _HID (Hardware ID)

        This object is used to supply OSPM with the device’s PNP ID or ACPI ID. 

        When describing a platform, use of any _HID objects is optional. 
However, a _HID object must be

        used to describe any device that will be enumerated by OSPM. OSPM only 
enumerates a device

        when no bus enumerator can detect the device ID. For example, devices 
on an ISA bus are

        enumerated by OSPM. Use the _ADR object to describe devices enumerated 
by bus enumerators

        other than OSPM.

Note: "detect the device ID" not "enumerate the device" which I think
means there's a driver matching this vendor/device ID.

So it seems fine to have _ADR so device is enumerated, and still have
_HID e.g. so ACPI driver can be loaded as fallback if there's
no bus driver.

Note I am not saying the patch itself is not correct.
Maybe these devices are not on any standard bus and that
is why they should not have _ADR? I have not looked.

I am just saying that spec does not seem to imply _HID and _ADR
can't coexist.

That's true; I did't find such statement either. Maybe what we can say is that the _ADR is senseless here.



CC Corey who added a device with both HID and ADR to x86 recenly.

Apropos Corey, why was HID APP0005 chosen?

Cc: Shannon Zhao <address@hidden>
Cc: Peter Maydell <address@hidden>
Cc: "Michael S. Tsirkin" <address@hidden>
Cc: Igor Mammedov <address@hidden>
Cc: address@hidden
Cc: address@hidden
  hw/arm/virt-acpi-build.c          |   8 --------
  tests/data/acpi/virt/DSDT         | Bin 18449 -> 18426 bytes
  tests/data/acpi/virt/DSDT.memhp   | Bin 19786 -> 19763 bytes
  tests/data/acpi/virt/DSDT.numamem | Bin 18449 -> 18426 bytes
  4 files changed, 8 deletions(-)

diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c
index 9f4c7d1889..be752c0ad8 100644
--- a/hw/arm/virt-acpi-build.c
+++ b/hw/arm/virt-acpi-build.c
@@ -78,11 +78,6 @@ static void acpi_dsdt_add_uart(Aml *scope, const MemMapEntry 
                               AML_EXCLUSIVE, &uart_irq, 1));
      aml_append(dev, aml_name_decl("_CRS", crs));
- /* The _ADR entry is used to link this device to the UART described
-     * in the SPCR table, i.e. SPCR.base_address.address == _ADR.
-     */
-    aml_append(dev, aml_name_decl("_ADR", aml_int(uart_memmap->base)));
      aml_append(scope, dev);
@@ -170,7 +165,6 @@ static void acpi_dsdt_add_pci(Aml *scope, const MemMapEntry *memmap,
      aml_append(dev, aml_name_decl("_CID", aml_string("PNP0A03")));
      aml_append(dev, aml_name_decl("_SEG", aml_int(0)));
      aml_append(dev, aml_name_decl("_BBN", aml_int(0)));
-    aml_append(dev, aml_name_decl("_ADR", aml_int(0)));
      aml_append(dev, aml_name_decl("_UID", aml_string("PCI0")));
      aml_append(dev, aml_name_decl("_STR", aml_unicode("PCIe 0 Device")));
      aml_append(dev, aml_name_decl("_CCA", aml_int(1)));
@@ -334,7 +328,6 @@ static void acpi_dsdt_add_gpio(Aml *scope, const 
MemMapEntry *gpio_memmap,
      Aml *dev = aml_device("GPO0");
      aml_append(dev, aml_name_decl("_HID", aml_string("ARMH0061")));
-    aml_append(dev, aml_name_decl("_ADR", aml_int(0)));
      aml_append(dev, aml_name_decl("_UID", aml_int(0)));
Aml *crs = aml_resource_template();
@@ -364,7 +357,6 @@ static void acpi_dsdt_add_power_button(Aml *scope)
      Aml *dev = aml_device(ACPI_POWER_BUTTON_DEVICE);
      aml_append(dev, aml_name_decl("_HID", aml_string("PNP0C0C")));
-    aml_append(dev, aml_name_decl("_ADR", aml_int(0)));
      aml_append(dev, aml_name_decl("_UID", aml_int(0)));
      aml_append(scope, dev);
diff --git a/tests/data/acpi/virt/DSDT b/tests/data/acpi/virt/DSDT

Please do not include binary changes in acpi patches.

See comment at the top of tests/bios-tables-test.c for documentation
on how to update these.



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