Re: [PATCH v12 00/25] Linux RISC-V AIA Support

From: "Björn Töpel" <bjorn@kernel.org>
To: Anup Patel <apatel@ventanamicro.com>
Cc: Anup Patel <anup@brainfault.org>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	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>,
	devicetree@vger.kernel.org,
	Saravana Kannan <saravanak@google.com>,
	Marc Zyngier <maz@kernel.org>,
	linux-kernel@vger.kernel.org, Atish Patra <atishp@atishpatra.org>,
	linux-riscv@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org,
	Andrew Jones <ajones@ventanamicro.com>
Subject: Re: [PATCH v12 00/25] Linux RISC-V AIA Support
Date: Wed, 07 Feb 2024 13:55:39 +0100	[thread overview]
Message-ID: <87sf24mo1g.fsf@all.your.base.are.belong.to.us> (raw)
In-Reply-To: <87plx8y5s3.fsf@all.your.base.are.belong.to.us>

Björn Töpel <bjorn@kernel.org> writes:

>>> Hmm, seems like we're talking past each other, or at least I get the
>>> feeling I can't get my opinions out right. I'll try to do a quick PoC,
>>> to show you what I mean. That's probably easier than just talking about
>>> it. ...and maybe I'll come realizing I'm all wrong!
>>
>> I suggest to wait for my v13 and try something on top of that
>> otherwise we might duplicate efforts.
>
> OK!

I did some really rough code sketching, and I'm confident that you can
get rid of all ids_enabled_bitmap, hwirqs_used_bitmap, and the
corresponding functions/locks. I'd say one lock is enough, and the key
is having the per-cpu imsic_local_priv.vectors change from struct
imsic_vector * to struct imsic_vector **.

Using smp_call_function_single() to IPI enable (and disable if you don't
want to use the lazy timer disable mechanism) seems feasible as well!

(Let me know if you don't have the spare cycles, and I can help out.)

Björn

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