linux-kernel - Re: [PATCH v5 1/1] irqchip/gic-v3: Enable non-coherent redistributors/ITSes ACPI probing

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Date: Wed, 05 Jun 2024 09:40:34 +0100
From: Marc Zyngier <maz@...nel.org>
To: Lorenzo Pieralisi <lpieralisi@...nel.org>
Cc: linux-kernel@...r.kernel.org, "Rafael J. Wysocki" <rafael@...nel.org>,
 Robin Murphy <robin.murphy@....com>, Mark Rutland <mark.rutland@....com>,
 linux-arm-kernel@...ts.infradead.org, linux-acpi@...r.kernel.org,
 acpica-devel@...ts.linux.dev, Fang Xiang <fangxiang3@...omi.com>, Robert
 Moore <robert.moore@...el.com>
Subject: Re: [PATCH v5 1/1] irqchip/gic-v3: Enable non-coherent
 redistributors/ITSes ACPI probing

On 2024-06-05 08:14, Lorenzo Pieralisi wrote:
> On Mon, Apr 22, 2024 at 10:42:19AM +0200, Lorenzo Pieralisi wrote:
>> On Tue, Jan 23, 2024 at 12:03:32PM +0100, Lorenzo Pieralisi wrote:
>> > The GIC architecture specification defines a set of registers for
>> > redistributors and ITSes that control the sharebility and cacheability
>> > attributes of redistributors/ITSes initiator ports on the interconnect
>> > (GICR_[V]PROPBASER, GICR_[V]PENDBASER, GITS_BASER<n>).
>> >
>> > Architecturally the GIC provides a means to drive shareability and
>> > cacheability attributes signals but it is not mandatory for designs to
>> > wire up the corresponding interconnect signals that control the
>> > cacheability/shareability of transactions.
>> >
>> > Redistributors and ITSes interconnect ports can be connected to
>> > non-coherent interconnects that are not able to manage the
>> > shareability/cacheability attributes; this implicitly makes the
>> > redistributors and ITSes non-coherent observers.
>> >
>> > To enable non-coherent GIC designs on ACPI based systems, parse the MADT
>> > GICC/GICR/ITS subtables non-coherent flags to determine whether the
>> > respective components are non-coherent observers and force the
>> > shareability attributes to be programmed into the redistributors and
>> > ITSes registers.
>> >
>> > An ACPI global function (acpi_get_madt_revision()) is added to retrieve
>> > the MADT revision, in that it is essential to check the MADT revision
>> > before checking for flags that were added with MADT revision 7 so that
>> > if the kernel is booted with an ACPI MADT table with revision < 7 it
>> > skips parsing the newly added flags (that should be zeroed reserved
>> > values for MADT versions < 7 but they could turn out to be buggy and
>> > should be ignored).
>> >
>> > Signed-off-by: Lorenzo Pieralisi <lpieralisi@...nel.org>
>> > Cc: Robin Murphy <robin.murphy@....com>
>> > Cc: Mark Rutland <mark.rutland@....com>
>> > Cc: "Rafael J. Wysocki" <rafael@...nel.org>
>> > Cc: Marc Zyngier <maz@...nel.org>
>> > ---
>> >  drivers/acpi/processor_core.c    | 15 +++++++++++++++
>> >  drivers/irqchip/irq-gic-v3-its.c |  4 ++++
>> >  drivers/irqchip/irq-gic-v3.c     |  9 +++++++++
>> >  include/linux/acpi.h             |  3 +++
>> >  4 files changed, 31 insertions(+)
>> 
>> Hi Marc, Rafael,
>> 
>> I would kindly ask you please what to do with this patch, it still
>> applies to v6.9-rc5 - I can resend it if needed, ACPICA changes
>> are already merged as-per the cover letter.
> 
> Hi Marc, Rafael,
> 
> I would kindly ask please what to do with this patch, rebased to 
> v6.10-rc1,
> I can resend it if that's preferred, please let me know.

Please resend it with my:

Acked-by: Marc Zyngier <maz@...nel.org>

and Cc'ing Thomas Gleixner.

Thanks,

         M.
-- 
Jazz is not dead. It just smells funny...