From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793121376; b=f1m2U4TuMNKhf4uh3Xetx5a3mC3Y/76lwekdNJi624u8RKt3QDUuJUA16KmXUBGKIXq7 i1Bco97D8ONAvb2dyV8Z6fcD8/EnHDsw3Ch81t0HBjItUiTOl+EjS7whGa4tgH+QSceFE y2YheSpx7XnKpRXPBYVQEZ9aC5CuZMjpDWGXuUYVXRG+Ve0+FQb+Wq3Dzo22uxvqKtHsx K/dy6ZbnAseGIPgNM8+Fe6ilo6vn69W1tRXIc87BDTtYI0I6IqsP8cBb+lHmaDXE64oz5 D+hIjaKCEMbUmGrTVtgwnluARkBvZElZhYRDAyWtfcrDMVIVgRNA2MsgIZOgzZ1RD/A== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793121376; h=Received:DKIM-Signature:Message-ID:From:Subject:Reply-To:To:Cc: In-Reply-To:References:Content-Type:Content-Transfer-Encoding:Date; bh=dPGqEZhz1K47fCMbegZC+JlyKQdqvlPhCRpJ+bR/mwI=; b=UYd99e0TJWfhVo+hkr/Cuv7RKsRSrebJ77fQI6wPMUZDkOOfd2lxGzTW9svKATgleoOo LzA722mwhQqab0OhbH/5H68W3RWFItBmqmKnWTLh2sxoVATjACu7ghNM1aRjIQrCUEFUD Aq+g1xkV/p1UzwgnKePxmk1o2youzYpUfcW4Nr7O2NhL6oqNVfP0c3hmk63VkV9zNWHSa sRKuMcQNmyBo2YO6I0lJPU0gUuq3cgH75xL4qq77Hh4qFTaeix+gQJpdDj11cTqBJGtae PdQHsAxAjVgin8iVeVWP/ddjDS7vKnopqdSTd6FxB7WC7SusNQ9hnEA2IupQ4nS2AsA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=frNhDIqV; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7AB66606A31A for ; Tue, 27 Oct 2026 17:16:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=frNhDIqV Received: by smtp.kernel.org (Postfix) with ESMTPSA id 09CCD1F01825; Tue, 27 Oct 2026 17:16:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793121376; bh=dPGqEZhz1K47fCMbegZC+JlyKQdqvlPhCRpJ+bR/mwI=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=frNhDIqVI8ijY53Nf6Aiw+AXX8hrFNsdP5FJJlND75ByFsWYomZo6hr2oMVxKC3mP l9MQ/e9VkNmwW0t7XaejIIbXp9pharD19ppxsOO7jkyArM2/91sUzIJHgv4JgGZ1gH oxPGVzBg7AVj3ltjv6dXrViIDHlM9JFL1+osbSRdPu97G4ShyPg/VjsXnVybtNNP2u GPyWXqOX6P9HFNZfpC16ENHQrvaBGCXKRwtImMh0gnOkprbpvH9zsA9b4DAol9y2WF 3hBK4uZrCkD46lJEAaKJ0m5gQ5e0fZjEQ4McrWh6tgg12uhaLQBCpxwXNTc7U/t29u uDbtLYZezBvIg== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [PATCH v4] serial: 8250_dw: preserve BUSY-safe fractional divisor programming Reply-To: sashiko-reviews@lists.linux.dev To: "James Hilliard" Cc: linux-serial@vger.kernel.org In-Reply-To: <20261027-submit-serial-8250-dw-divisor-v1-v4-1-41714a75e15a@gmail.com> References: <20261027-submit-serial-8250-dw-divisor-v1-v4-1-41714a75e15a@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Tue, 27 Oct 2026 17:16:15 +0000 X-Mailing-List: linux-serial@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list > dw8250_probe() installs a divisor setter that makes the UART idle and > checks DLAB before writing DLL and DLH. When dw8250_setup_port() detects > fractional-divisor support, it replaces that setter with the library's > callback. The replacement writes DLF and uses serial8250_do_set_divisor(), > bypassing the divisor setter's idle sequence and DLAB readback. >=20 > If the LCR update fails to set DLAB, the subsequent divisor writes can > reach TX and IER instead of DLL and DLH. >=20 > Expose the library's fractional-divisor calculation and DLF write as > shared helpers. Install the BUSY-safe setter after hardware discovery and > use the shared DLF helper to program the fractional field only after DLAB > has been confirmed, alongside DLL and DLH. Keep fractional-divisor > detection and calculator selection in the library, preserving the core > calculation for integer-only ports. Let the shared DLF setter check for > fractional-divisor support so callers can use it for either kind of port. >=20 > Fixes: a7b9ce39fbe4 ("serial: 8250_dw: Ensure BUSY is deasserted") > Cc: stable@vger.kernel.org > Signed-off-by: James Hilliard Sashiko has reviewed this patch and found no issues. --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20261027-submit-ser= ial-8250-dw-divisor-v1-v4-1-41714a75e15a@gmail.com?part=3D1