Re: [PATCH v14 11/18] irqchip: Add RISC-V incoming MSI controller early driver

From: Anup Patel <anup@brainfault.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: "Anup Patel" <apatel@ventanamicro.com>,
	devicetree@vger.kernel.org, "Conor Dooley" <conor+dt@kernel.org>,
	"Saravana Kannan" <saravanak@google.com>,
	"Marc Zyngier" <maz@kernel.org>,
	"Atish Patra" <atishp@atishpatra.org>,
	linux-kernel@vger.kernel.org, "Björn Töpel" <bjorn@kernel.org>,
	"Rob Herring" <robh+dt@kernel.org>,
	"Palmer Dabbelt" <palmer@dabbelt.com>,
	"Krzysztof Kozlowski" <krzysztof.kozlowski+dt@linaro.org>,
	"Paul Walmsley" <paul.walmsley@sifive.com>,
	linux-riscv@lists.infradead.org,
	"Frank Rowand" <frowand.list@gmail.com>,
	linux-arm-kernel@lists.infradead.org,
	"Andrew Jones" <ajones@ventanamicro.com>
Subject: Re: [PATCH v14 11/18] irqchip: Add RISC-V incoming MSI controller early driver
Date: Fri, 23 Feb 2024 15:22:59 +0530	[thread overview]
Message-ID: <CAAhSdy1jdHsuwRhbRgig98-AVDOGwp_XxHurg9o3Rsj1AVOqbA@mail.gmail.com> (raw)
In-Reply-To: <87a5nreg94.ffs@tglx>

On Fri, Feb 23, 2024 at 1:58 PM 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:starting",
> > +                       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

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