From: "Jernej Škrabec" <jernej.skrabec@gmail.com>
To: daniel.lezcano@kernel.org, tglx@kernel.org,
Felix Yan <felixonmars@archlinux.org>
Cc: wens@kernel.org, samuel@sholland.org, indrek.kruusa@gmail.com,
linux-kernel@vger.kernel.org, linux-sunxi@lists.linux.dev,
linux-riscv@lists.infradead.org,
Felix Yan <felixonmars@archlinux.org>,
stable@vger.kernel.org
Subject: Re: [PATCH] clocksource/drivers/timer-sun4i: Advertise a real minimum delta
Date: Sat, 27 Jun 2026 08:48:28 +0200 [thread overview]
Message-ID: <cyKZfOi8QVGppYlWqaO5QA@gmail.com> (raw)
In-Reply-To: <20260624220434.4183732-1-felixonmars@archlinux.org>
Dne četrtek, 25. junij 2026 ob 00:04:34 Srednjeevropski poletni čas je Felix Yan napisal(a):
> sun4i_clkevt_next_event() compensates for the timer stop/start
> synchronization delay by programming evt - TIMER_SYNC_TICKS into the
> hardware interval register. The clockevent device currently advertises
> TIMER_SYNC_TICKS as min_delta_ticks, so the clockevents core is allowed
> to call set_next_event() with evt == TIMER_SYNC_TICKS.
>
> That programs a zero-tick interval. With oneshot/highres/nohz timer
> operation this can leave the next event stuck, which was observed as a
> boot hang on Allwinner D1 after the clockevents core started reusing
> forced minimum-delta events.
>
> Advertise one extra tick instead, so the smallest event accepted by the
> core still programs at least one hardware tick after the synchronization
> compensation.
>
> Fixes: 12e1480bcb49 ("clocksource: sun4i: Report the minimum tick that we can program")
> Cc: stable@vger.kernel.org
> Reported-by: Indrek Kruusa <indrek.kruusa@gmail.com>
> Closes: https://lore.kernel.org/linux-riscv/CA+fTLhgLmTY+exGujKf8OYYQvcEW5X5NJ_5sLq2AYL6zER2c0A@mail.gmail.com/
> Assisted-by: Codex:gpt-5.5
> Signed-off-by: Felix Yan <felixonmars@archlinux.org>
Acked-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Best regards,
Jernej
WARNING: multiple messages have this Message-ID (diff)
From: "Jernej Škrabec" <jernej.skrabec@gmail.com>
To: daniel.lezcano@kernel.org, tglx@kernel.org,
Felix Yan <felixonmars@archlinux.org>
Cc: wens@kernel.org, samuel@sholland.org, indrek.kruusa@gmail.com,
linux-kernel@vger.kernel.org, linux-sunxi@lists.linux.dev,
linux-riscv@lists.infradead.org,
Felix Yan <felixonmars@archlinux.org>,
stable@vger.kernel.org
Subject: Re: [PATCH] clocksource/drivers/timer-sun4i: Advertise a real minimum delta
Date: Sat, 27 Jun 2026 08:48:28 +0200 [thread overview]
Message-ID: <cyKZfOi8QVGppYlWqaO5QA@gmail.com> (raw)
In-Reply-To: <20260624220434.4183732-1-felixonmars@archlinux.org>
Dne četrtek, 25. junij 2026 ob 00:04:34 Srednjeevropski poletni čas je Felix Yan napisal(a):
> sun4i_clkevt_next_event() compensates for the timer stop/start
> synchronization delay by programming evt - TIMER_SYNC_TICKS into the
> hardware interval register. The clockevent device currently advertises
> TIMER_SYNC_TICKS as min_delta_ticks, so the clockevents core is allowed
> to call set_next_event() with evt == TIMER_SYNC_TICKS.
>
> That programs a zero-tick interval. With oneshot/highres/nohz timer
> operation this can leave the next event stuck, which was observed as a
> boot hang on Allwinner D1 after the clockevents core started reusing
> forced minimum-delta events.
>
> Advertise one extra tick instead, so the smallest event accepted by the
> core still programs at least one hardware tick after the synchronization
> compensation.
>
> Fixes: 12e1480bcb49 ("clocksource: sun4i: Report the minimum tick that we can program")
> Cc: stable@vger.kernel.org
> Reported-by: Indrek Kruusa <indrek.kruusa@gmail.com>
> Closes: https://lore.kernel.org/linux-riscv/CA+fTLhgLmTY+exGujKf8OYYQvcEW5X5NJ_5sLq2AYL6zER2c0A@mail.gmail.com/
> Assisted-by: Codex:gpt-5.5
> Signed-off-by: Felix Yan <felixonmars@archlinux.org>
Acked-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Best regards,
Jernej
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next prev parent reply other threads:[~2026-06-27 6:48 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-18 19:36 Booting v7.1-rc4 hangs on a single core CPU, bisected to ff1c0c5d07028 Indrek Kruusa
2026-06-24 22:04 ` [PATCH] clocksource/drivers/timer-sun4i: Advertise a real minimum delta Felix Yan
2026-06-24 22:04 ` Felix Yan
2026-06-24 22:14 ` sashiko-bot
2026-06-25 19:58 ` Indrek Kruusa
2026-06-25 19:58 ` Indrek Kruusa
2026-06-27 6:48 ` Jernej Škrabec [this message]
2026-06-27 6:48 ` Jernej Škrabec
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