From: Julien Grall <julien.grall@arm.com>
To: Shanker Donthineni <shankerd@codeaurora.org>,
xen-devel <xen-devel@lists.xensource.com>
Cc: Philip Elcan <pelcan@codeaurora.org>,
Stefano Stabellini <sstabellini@kernel.org>,
Vikram Sethi <vikrams@codeaurora.org>,
Steve Capper <Steve.Capper@arm.com>
Subject: Re: [PATCH v2] arm/gic-v3: Fix ACPI probe fail on GICv4 hardware
Date: Fri, 27 May 2016 17:10:47 +0100 [thread overview]
Message-ID: <57487187.3080408@arm.com> (raw)
In-Reply-To: <5748681E.9020206@codeaurora.org>
Hello Shanker,
On 27/05/16 16:30, Shanker Donthineni wrote:
> On 05/27/2016 10:10 AM, Julien Grall wrote:
>> On 27/05/16 16:00, Shanker Donthineni wrote:
>>> The current driver ACPI probe fails on hardware which has GICv4
>>> version, even though it is fully compatible to GICv3. This patch
>>> fixes the issue by registering the same probe function for GICv4
>>> hardware.
>>>
>>> Signed-off-by: Shanker Donthineni <shankerd@codeaurora.org>
>>> ---
>>> Changes since v1:
>>> - Edit commit text.
>>> - Fix BUG() in xen/arch/arm/domain.c
>>
>> Please see my latest comment on the previous version [1].
>>
>> To go further, the ACPI tables may not represent the actual hardware. It is possible to have ACPI tables describing a GICv2 whilst the real hardware is a GICv3.
>>
> Yes, it is absolutely valid and UEFI firmware can decide what to be exported to OS by changing the version number in ACPI MADT table.
>
> On Qualcomm Technologies QDF2XXX platforms, GIC version set to 4.
To be clear, I am not against adding support of GICv4 in Xen. My concern
is how the patch add it. Exposing GICv4 beyond the GICv3 driver is not
necessary today.
Better to keep as small as possible until we figure out how Xen will
support GICv4 features.
I.e, the following the code should be enough.
ACPI_DEVICE_START(acgicv4, "GICv4", DEVICE_GIC)
.class_type = ACPI_MADT_GIC_VERSION_V4,
.init = gicv3_acpi_preinit,
ACPI_DEVICE_END
>
>> Xen will use the GICv2 driver and not the GICv3. So the helper will return GIC_V2 (and not GIC_V3).
>>
>
> The current xen is supporting both the GICv2 and GICv3 for ACPI based boot.
>
> ACPI_DEVICE_START(agicv3, "GICv3", DEVICE_GIC)
> .class_type = ACPI_MADT_GIC_VERSION_V3,
> .init = gicv3_acpi_preinit,
> ACPI_DEVICE_END
>
> ACPI_DEVICE_START(agicv2, "GICv2", DEVICE_GIC)
> .class_type = ACPI_MADT_GIC_VERSION_V2,
> .init = gicv2_acpi_preinit,
> ACPI_DEVICE_END
Regards,
--
Julien Grall
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xen.org
http://lists.xen.org/xen-devel
prev parent reply other threads:[~2016-05-27 16:10 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-27 15:00 [PATCH v2] arm/gic-v3: Fix ACPI probe fail on GICv4 hardware Shanker Donthineni
2016-05-27 15:10 ` Julien Grall
2016-05-27 15:30 ` Shanker Donthineni
2016-05-27 16:10 ` Julien Grall [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=57487187.3080408@arm.com \
--to=julien.grall@arm.com \
--cc=Steve.Capper@arm.com \
--cc=pelcan@codeaurora.org \
--cc=shankerd@codeaurora.org \
--cc=sstabellini@kernel.org \
--cc=vikrams@codeaurora.org \
--cc=xen-devel@lists.xensource.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.