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

[Guoheyi <guoheyi@huawei.com>]

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 <guoheyi@huawei.com>
>> 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. 1
>
> 	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.

Thanks,

Heyi

>
>
>> CC Corey who added a device with both HID and ADR to x86 recenly.
>>
>> Apropos Corey, why was HID APP0005 chosen?
>>
>>> ---
>>> Cc: Shannon Zhao <shannon.zhaosl@gmail.com>
>>> Cc: Peter Maydell <peter.maydell@linaro.org>
>>> Cc: "Michael S. Tsirkin" <mst@redhat.com>
>>> Cc: Igor Mammedov <imammedo@redhat.com>
>>> Cc: qemu-arm@nongnu.org
>>> Cc: qemu-devel@nongnu.org
>>> ---
>>>   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 *uart_memmap,
>>>                                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.
>>
>> -- 
>> MST
>
> .