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Fri, 26 Jun 2026 23:48:29 -0700 (PDT) From: Jernej =?UTF-8?B?xaBrcmFiZWM=?= To: daniel.lezcano@kernel.org, tglx@kernel.org, Felix Yan 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 , 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 Message-ID: In-Reply-To: <20260624220434.4183732-1-felixonmars@archlinux.org> References: <20260624220434.4183732-1-felixonmars@archlinux.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Dne =C4=8Detrtek, 25. junij 2026 ob 00:04:34 Srednjeevropski poletni =C4=8D= as 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 =3D=3D TIMER_SYNC_TICKS. >=20 > 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. >=20 > Advertise one extra tick instead, so the smallest event accepted by the > core still programs at least one hardware tick after the synchronization > compensation. >=20 > Fixes: 12e1480bcb49 ("clocksource: sun4i: Report the minimum tick that we= can program") > Cc: stable@vger.kernel.org > Reported-by: Indrek Kruusa > Closes: https://lore.kernel.org/linux-riscv/CA+fTLhgLmTY+exGujKf8OYYQvcEW= 5X5NJ_5sLq2AYL6zER2c0A@mail.gmail.com/ > Assisted-by: Codex:gpt-5.5 > Signed-off-by: Felix Yan Acked-by: Jernej Skrabec Best regards, Jernej