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=1792821468; b=rtG7kiO8IC1Et12SUZQ/odFizD0M9DuvAJ3JaDrKhspLhQ04FF1e8A6S3TtVAVPamUWQ +d6QFpX+p4n9gejgAsmeLnvHljlbzKbp1x4FZtSYIS49XiLdFFnOPPqS1n8w9N4X04VRl o4biCQH4/HicfDDZOH0Gr6T2+RvdBWLKc3KAC03BbH0CJGvFKH7Bf4xDuGPka5hY5STZq hrIy03uU78SM0rY+bcyPH8dgIlu2aNCZsI+toibYfT6nJqcByv/ryHO1q5pOhe27SIp1Q HR0Dw7qfuCzL9drSVkNcX0Omoyx0Jl0hytnCKbxRt4e3OWaktD8dK/Uvu/+rVXcQsJg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792821468; h=Received:DKIM-Signature:Message-ID:From:Subject:Reply-To:To:Cc: In-Reply-To:References:Content-Type:Content-Transfer-Encoding:Date; bh=bOQjfnOqEO0vdNcHx0bOWlgK9aVHH/nHX7+pCef+BYQ=; b=SBoykQJlrdofbXsj0wovqjv6njMYE2X67enJvgO0MsB8q6SLjZvfgnRi6i7Bcs4ZMOkc gtfEdRX8VVWk27JhdP7zQqn69tEmccaEfvwHa9ZPR3hcYy2LWpe6OJDNYiJVIPu2J5lLp F/6DNHENskIqC1DWapRI2rNqeh6OnOpSg2OWOHFajYyEM+aSVAgbPF9kWMUyNzcNQDJhv Uv2zFMXAFjWw+BNuJcOVzdFNaWOgZLQYobK4RcdxgRAIjac6S5kqHVoWxzzwEkQ/zQkYX 3GHbUmC89wYonuatiWfAJZavMm/Ebi3jwUJ0X2DjICvIDpAw0Do8XFTNB2Y0hmIev0g== 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=GUn8sUw0; 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) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AAECA606A31A for ; Sat, 24 Oct 2026 05:57:47 +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=GUn8sUw0 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2FDEA1F01825; Sat, 24 Oct 2026 05:57:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1792821467; bh=bOQjfnOqEO0vdNcHx0bOWlgK9aVHH/nHX7+pCef+BYQ=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=GUn8sUw0lBm4EWwpg1KNCDG9PU20INsSPyTdSMW74QWjY1oijYGKMXfrYdxRQWawi mHaFa4CFF7iHS21bIjAmyv3gU6PmSsAfGZusbDQ91iYyFi6oGtb9GgFXDeOP3Av/Jn MP9Q3klvPqLvozkVX9ldAJH7T5G1IYqUAWQhsHSE8Nxev9Fnr3l0G3g5E62VjmRj/P drra3hJbwe+QXPIntJoZVKhJ5UTdCDm5rFWOPN4oURLnULalLVW46ZMtync25nA0CB OO8UpXmB4722vzytkLbaDSowQUkZ0yuqCicJC3CoxAyGUI9sTIhm49JWTwtqaVMMa0 NYs+5rJgSXhvQ== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [PATCH] 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: <20261023-submit-serial-8250-dw-divisor-v1-v1-1-f452d4bb1b1f@gmail.com> References: <20261023-submit-serial-8250-dw-divisor-v1-v1-1-f452d4bb1b1f@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Sat, 24 Oct 2026 05:57:46 +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 > Install the BUSY-safe setter after hardware discovery and extend it to > write DLF when fractional divisors are supported. Program both divisor > fields only after DLAB has been confirmed, retaining the fractional > divisor calculation selected by dw8250_setup_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/20261023-submit-ser= ial-8250-dw-divisor-v1-v1-1-f452d4bb1b1f@gmail.com?part=3D1