linux-kernel - Re: [PATCH v5 2/4] dt-bindings: x86: apic: Introduce new optional bool property for lapic

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Date:   Wed, 30 Nov 2022 15:21:44 -0600
From:   Rob Herring <robh@...nel.org>
To:     Rahul Tanwar <rtanwar@...linear.com>
Cc:     devicetree@...r.kernel.org,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        x86@...nel.org, Borislav Petkov <bp@...en8.de>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Marc Zyngier <maz@...nel.org>, linux-kernel@...r.kernel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>, linux-lgm-soc@...linear.com,
        Rob Herring <robh+dt@...nel.org>
Subject: Re: [PATCH v5 2/4] dt-bindings: x86: apic: Introduce new optional
 bool property for lapic


On Thu, 24 Nov 2022 16:41:41 +0800, Rahul Tanwar wrote:
> Intel defines a few possible interrupt delivery modes. With respect
> to boot/init time, mainly two interrupt delivery modes are possible.
> PIC Mode - Legacy external 8259 compliant PIC interrupt controller.
> Virtual Wire Mode - use lapic as virtual wire interrupt delivery mode.
> 
> For ACPI or MPS spec compliant systems, it is figured out by some read
> only bit field/s available in their respective defined data structures.
> But for OF based systems, it is by default set to PIC mode. Presently,
> it is hardcoded to legacy PIC mode for OF based x86 systems with no
> option to choose the configuration between PIC mode & virtual wire mode.
> 
> For this purpose, introduce a new boolean property for interrupt
> controller node of lapic which can allow it to be configured to virtual
> wire mode as well.
> 
> Property name: 'intel,virtual-wire-mode'
> Type: Boolean
> 
> If not present/not defined, interrupt delivery mode defaults to legacy PIC
> mode. If present/defined, interrupt delivery mode is set to virtual wire
> mode.
> 
> Suggested-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> Signed-off-by: Rahul Tanwar <rtanwar@...linear.com>
> ---
>  .../interrupt-controller/intel,ce4100-lapic.yaml   | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 

Reviewed-by: Rob Herring <robh@...nel.org>