From: Igor Mammedov <imammedo@redhat.com>
To: Guoheyi <guoheyi@huawei.com>
Cc: Peter Maydell <peter.maydell@linaro.org>,
"Michael S. Tsirkin" <mst@redhat.com>,
qemu-devel@nongnu.org, Shannon Zhao <shannon.zhaosl@gmail.com>,
qemu-arm@nongnu.org, Corey Minyard <cminyard@mvista.com>,
wanghaibin.wang@huawei.com
Subject: Re: [PATCH 2/2] arm/virt/acpi: remove _ADR from devices identified by _HID
Date: Thu, 16 Jan 2020 14:25:08 +0100 [thread overview]
Message-ID: <20200116142508.1d82af31@redhat.com> (raw)
In-Reply-To: <a4992b63-e8e7-7f54-341e-f7dd3d7e8880@huawei.com>
On Thu, 16 Jan 2020 19:56:19 +0800
Guoheyi <guoheyi@huawei.com> wrote:
> 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.
>
> More reading on the spec, I found a statement as below
> (https://uefi.org/sites/default/files/resources/ACPI_6_3_May16.pdf,
> section 6.1, on top of page 343):
I'd replace 'It does not make sense ...' sentence with pointer to spec
and quote below in commit message.
> A device object must contain either an _HID object or an _ADR object,
> but should not contain both
[...]
next prev parent reply other threads:[~2020-01-16 13:26 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-19 6:47 [PATCH 0/2] Some cleanup in arm/virt/acpi Heyi Guo
2019-12-19 6:47 ` [PATCH 1/2] arm/virt/acpi: remove meaningless sub device "PR0" from PCI0 Heyi Guo
2020-01-13 12:37 ` Igor Mammedov
2020-01-16 12:36 ` Guoheyi
2020-01-21 3:48 ` Guoheyi
2020-01-21 6:35 ` Michael S. Tsirkin
2020-01-22 5:39 ` Michael S. Tsirkin
2020-01-22 6:38 ` Guoheyi
2019-12-19 6:47 ` [PATCH 2/2] arm/virt/acpi: remove _ADR from devices identified by _HID Heyi Guo
2020-01-05 12:33 ` Michael S. Tsirkin
2020-01-05 12:53 ` Michael S. Tsirkin
2020-01-06 2:10 ` Guoheyi
2020-01-13 8:46 ` Guoheyi
2020-01-16 11:56 ` Guoheyi
2020-01-16 13:25 ` Igor Mammedov [this message]
2020-01-17 1:54 ` Guoheyi
2020-01-05 22:54 ` Corey Minyard
2020-01-06 9:39 ` Michael S. Tsirkin
2020-01-06 13:07 ` Corey Minyard
2020-01-06 15:51 ` Peter Maydell
2020-01-15 2:03 ` Guoheyi
2020-01-15 6:30 ` Michael S. Tsirkin
2020-01-15 9:25 ` Guoheyi
2020-01-15 10:53 ` Michael S. Tsirkin
2020-01-15 10:55 ` Michael S. Tsirkin
2020-01-16 12:24 ` Peter Maydell
2020-01-17 2:08 ` Guoheyi
2020-01-13 12:08 ` Igor Mammedov
2020-01-13 13:57 ` Guoheyi
2020-01-13 15:26 ` Andrew Jones
2020-01-15 1:25 ` Guoheyi
2020-01-15 12:08 ` Igor Mammedov
2019-12-19 12:34 ` [PATCH 0/2] Some cleanup in arm/virt/acpi Michael S. Tsirkin
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