From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Troy Mitchell <troy.mitchell@linux.dev>
Cc: "Thomas Gleixner" <tglx@kernel.org>,
"Radu Rendec" <radu@rendec.net>,
"Anup Patel" <anup@brainfault.org>,
"Paul Walmsley" <pjw@kernel.org>,
"Palmer Dabbelt" <palmer@dabbelt.com>,
"Albert Ou" <aou@eecs.berkeley.edu>,
"Alexandre Ghiti" <alex@ghiti.fr>,
"Clark Williams" <clrkwllms@kernel.org>,
"Steven Rostedt" <rostedt@goodmis.org>,
"Björn Töpel" <bjorn@rivosinc.com>,
"Anup Patel" <apatel@ventanamicro.com>,
linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org,
linux-rt-devel@lists.linux.dev
Subject: Re: [PATCH] irqchip/riscv-imsic: Synchronize remote state with IRQ work
Date: Tue, 3 Nov 2026 09:59:49 +0100 [thread overview]
Message-ID: <20261103085949.HPHNwwhb@linutronix.de> (raw)
In-Reply-To: <20261103-imsic-remote-sync-irqwork-v1-1-8b5c951fc62a@linux.dev>
On 2026-11-03 08:04:33 [+0000], Troy Mitchell wrote:
> Without a real broadcast device, the tick code falls back to the hrtimer
> based broadcast, which keeps one CPU's local timer running. Once the SoC
> timer is registered it replaces the hrtimer broadcast, and every CPU may
> stop its local timer in idle.
>
> On K3 the SoC timer interrupt goes through APLIC in MSI mode to IMSIC.
> When the CPU owning it goes offline, the interrupt is moved to a CPU
> that may already be idle with its local timer stopped. IMSIC leaves the
> enable on the new target to a timer on that CPU, and that timer can only
> fire through the broadcast interrupt, which is not enabled yet. The
> system stalls.
So the broadcast timer is moved on CPU which is idle and waking the CPU
is done by a timer, which does not work if the CPU is idle.
This makes sense.
Sebastian
next prev parent reply other threads:[~2026-11-03 8:59 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-03 8:04 Troy Mitchell
2026-11-03 8:59 ` Sebastian Andrzej Siewior [this message]
2026-11-03 15:52 ` Anup Patel
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20261103085949.HPHNwwhb@linutronix.de \
--to=bigeasy@linutronix.de \
--cc=alex@ghiti.fr \
--cc=anup@brainfault.org \
--cc=aou@eecs.berkeley.edu \
--cc=apatel@ventanamicro.com \
--cc=bjorn@rivosinc.com \
--cc=clrkwllms@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-riscv@lists.infradead.org \
--cc=linux-rt-devel@lists.linux.dev \
--cc=palmer@dabbelt.com \
--cc=pjw@kernel.org \
--cc=radu@rendec.net \
--cc=rostedt@goodmis.org \
--cc=tglx@kernel.org \
--cc=troy.mitchell@linux.dev \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®