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=1792867863; b=V4ROBpW5WOjMBz3xtN5YbhjDNdxJ7UetdN72HmnNwVq20+vjyqRef53wBx3Tjkn0ttGz m4Not6D6zKNTQAw4h8NO7+lOi8C1wJvrFTvrhIqM7xIIkWe1HF9Kah3VStXydiL9pJPds KyeJQwIyhDFI8pSSLhOBSl+2JEYFfICoqSTJeV+CdszwkruGf/yO5ktq5jYC4G68PAq1b BQIebmd2piiI82GSo3rR1xXCZ7TGln6WHxwSR8ebfanWCMyJxykB35EbUOh/nlErVmme4 CgnbnDQzIQyB9le62zEg7HMQ0PZefhw7ncGg3BK91jJlcaG73jREB+S+C3PAg+xZefg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792867863; h=Received:DKIM-Signature:Message-ID:From:Subject:Reply-To:To:Cc: In-Reply-To:References:Content-Type:Content-Transfer-Encoding:Date; bh=c9BvONVTbgQAlNLcKqFfDZz81U7vs1li8YUwS3SFn+s=; b=CZYJZbllRBt9AZtPX4jiVmfbZucia98+VGzq7rhWHve57YS6S6ahQQDz0z8iSOAtIMln pg2Ul2/vuQEkQRm04eIaThqwnhpdFOE6uYxOhbuNeQPQoQmEDFv2zZbIVbNgFGxenzX87 ASzXMrK8eOSIghQc2xvbOy7WiqkdM1BMXbmjFju3d53IeqNbqBnBDmxTWeJLZY/ikMFSb lZT4DHsjqsjNXnE45taySO6dI7ZzaX+1/Q+JV59NO0AL44DXSCyxA2Nz5mk7Rn7QOmIro wGs+B6wUsebRetWciU9tVfgzuTRI++rIq4i7kK66yGDaCIC9CtVgpP8I1n/0YWZWQTQ== 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=XTqM2GB4; 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 BD0D0606A31A for ; Sat, 24 Oct 2026 18:51:02 +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=XTqM2GB4 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 769D61F01825; Sat, 24 Oct 2026 18:51:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1792867862; bh=c9BvONVTbgQAlNLcKqFfDZz81U7vs1li8YUwS3SFn+s=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=XTqM2GB4VUZiQbg0JBeETIp7yJhj72gDDBrd6uc7RX74h8oH7l7W8nDPceUZq2h62 EDyvxy1BPQQ7F6xUq5uITRwhQSiIYHORX5PYKF7dChmKXdaOLIzS0c2z217A9Gm52F D8Wu5z8z15AVhnMZZOQCuUq5QbcZtOHVbO/nYIbMsuLLikQTqEqZx7oX2vebO5tB+x /qg99elfpm+JRmiXeUcD1vWiAztxqvsiS6IYZ6tN7ULIGoOPvi55d8cQu1Z/AiW+eE ms5ztgRy+HGt4Q0shEQ/TDKuCuTM6tDLbZ4tN8+KhcCvp6irm8JyldLlQO5zVSbWZi tAv90teZ9bcCQ== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [PATCH v2] 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: <20261024-submit-serial-8250-dw-divisor-v1-v2-1-032ca5338359@gmail.com> References: <20261024-submit-serial-8250-dw-divisor-v1-v2-1-032ca5338359@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Sat, 24 Oct 2026 18:51:02 +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. Select the shared calculator > when fractional divisors are supported, preserving the core calculation > for integer-only ports. >=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/20261024-submit-ser= ial-8250-dw-divisor-v1-v2-1-032ca5338359@gmail.com?part=3D1