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References: <20240222094006.1030709-1-apatel@ventanamicro.com>
 <20240222094006.1030709-12-apatel@ventanamicro.com> <87a5nreg94.ffs@tglx>
In-Reply-To: <87a5nreg94.ffs@tglx>
From: Anup Patel <anup@brainfault.org>
Date: Fri, 23 Feb 2024 15:22:59 +0530
Message-ID: <CAAhSdy1jdHsuwRhbRgig98-AVDOGwp_XxHurg9o3Rsj1AVOqbA@mail.gmail.com>
Subject: Re: [PATCH v14 11/18] irqchip: Add RISC-V incoming MSI controller
 early driver
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Anup Patel <apatel@ventanamicro.com>, Palmer Dabbelt <palmer@dabbelt.com>, 
	Paul Walmsley <paul.walmsley@sifive.com>, Rob Herring <robh+dt@kernel.org>, 
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>, Frank Rowand <frowand.list@gmail.com>, 
	Conor Dooley <conor+dt@kernel.org>, Marc Zyngier <maz@kernel.org>, =?UTF-8?B?QmrDtnJuIFTDtnBlbA==?= <bjorn@kernel.org>, 
	Atish Patra <atishp@atishpatra.org>, Andrew Jones <ajones@ventanamicro.com>, 
	Sunil V L <sunilvl@ventanamicro.com>, Saravana Kannan <saravanak@google.com>, 
	linux-riscv@lists.infradead.org, linux-arm-kernel@lists.infradead.org, 
	linux-kernel@vger.kernel.org, devicetree@vger.kernel.org
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On Fri, Feb 23, 2024 at 1:58=E2=80=AFPM Thomas Gleixner <tglx@linutronix.de=
> wrote:
>
> On Thu, Feb 22 2024 at 15:09, Anup Patel wrote:
> > +     /*
> > +      * Setup cpuhp state (must be done after setting imsic_parent_irq=
)
> > +      *
> > +      * Don't disable per-CPU IMSIC file when CPU goes offline
> > +      * because this affects IPI and the masking/unmasking of
> > +      * virtual IPIs is done via generic IPI-Mux
> > +      */
> > +     cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "irqchip/riscv/imsic:start=
ing",
> > +                       imsic_starting_cpu, imsic_dying_cpu);
>
> This is not really correct. IPIs should be working right away when a CPU
> comes online and on the unplug side until it really goes offline.
>
> So this wants to be in the starting range, i.e. between CPUHP_AP_OFFLINE
> and CPUHP_AP_ONLINE. No?

Yes, it has to be as early as possible but I was not sure about
introducing yet another driver specific CPUHP_AP_xyz state
considering CPUHP_AP_ONLINE_DYN worked fine.

Since you suggested, let me introduce
CPUHP_AP_IRQ_RISCV_IMSIC_STARTING in the next revision.

Regards,
Anup