From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bmailout3.hostsharing.net (bmailout3.hostsharing.net [176.9.242.62]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6107620B7E1 for ; Sun, 26 Oct 2025 09:25:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=176.9.242.62 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761470736; cv=none; b=kp71FDOfhoaIjVFwicEt0FyXs24E262M+8x+LkFcYjoX7IozGmPBEkXSZpHLGmLgED3C2Jnpa5jbdk8x+LaAdQ4rE0iEAlxP1HT7NlxLtEN6T1G+c9vpOmEz3d1/KbM9sdFo1unOWRGvzWsmKn/OIIaiO6scLBWwUeFjsyPFxKk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761470736; c=relaxed/simple; bh=Tss/zvoXsMS02VBKCezKNf/AvHbAfwnexNTEWA5QtKw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=LYXVsjo0pDD6680mWlMY5kEdPA8HaSJfBI3pU8MjsDAj96bmPa4AVeEx1ZRj6u+uN3YbTuRi6x25cn0DmMTqoWOvP0FWjWWWepfqnnVWcyulI19RpmJppQdFLy54piYMWwinfPD446kcNzZvC0eAnIJO9gGemZxhn0YQu1sFyqs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=wunner.de; spf=none smtp.mailfrom=h08.hostsharing.net; arc=none smtp.client-ip=176.9.242.62 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=wunner.de Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=h08.hostsharing.net Received: from h08.hostsharing.net (h08.hostsharing.net [IPv6:2a01:37:1000::53df:5f1c:0]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "*.hostsharing.net", Issuer "RapidSSL TLS RSA CA G1" (verified OK)) by bmailout3.hostsharing.net (Postfix) with ESMTPS id 7E7F02C02B8F; Sun, 26 Oct 2025 10:25:32 +0100 (CET) Received: by h08.hostsharing.net (Postfix, from userid 100393) id 4ADDD4A12; Sun, 26 Oct 2025 10:25:32 +0100 (CET) Date: Sun, 26 Oct 2025 10:25:32 +0100 From: Lukas Wunner To: Gerhard Engleder Cc: linux-serial@vger.kernel.org, gregkh@linuxfoundation.org, jirislaby@kernel.org, Gerhard Engleder Subject: Re: [PATCH v4 1/2] serial: Keep rs485 settings for devices without firmware node Message-ID: References: <20251023151229.11774-1-gerhard@engleder-embedded.com> <20251023151229.11774-2-gerhard@engleder-embedded.com> Precedence: bulk X-Mailing-List: linux-serial@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251023151229.11774-2-gerhard@engleder-embedded.com> On Thu, Oct 23, 2025 at 05:12:28PM +0200, Gerhard Engleder wrote: > Commit fe7f0fa43cef ("serial: 8250: Support rs485 devicetree properties") > retrieves rs485 properties for 8250 drivers. These properties are read > from the firmware node of the device within uart_get_rs485_mode(). If the > firmware node does not exist, then the rs485 flags are still reset. Thus, > 8250 driver cannot set rs485 flags to enable a defined rs485 mode during > driver loading. This is no problem so far, as no 8250 driver sets the > rs485 flags. > > The default rs485 mode can also be set by firmware nodes. But for some > devices a firmware node does not exist. E.g., for a PCIe based serial > interface on x86 no device tree is available and the ACPI information of > the BIOS often cannot by modified. In this case it shall be possible, > that a driver works out of the box by setting a reasonable default rs485 > mode. > > If no firmware node exists, then it should be possible for the driver to > set a reasonable default rs485 mode. Therefore, reset rs485 flags only > if a firmware node exists. > > Signed-off-by: Gerhard Engleder Reviewed-by: Lukas Wunner