From nobody Wed Dec 17 14:05:39 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0A154C46CA0 for ; Sun, 26 Nov 2023 16:09:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230364AbjKZQEX (ORCPT ); Sun, 26 Nov 2023 11:04:23 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57318 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230107AbjKZQEV (ORCPT ); Sun, 26 Nov 2023 11:04:21 -0500 Received: from mail-yw1-x1149.google.com (mail-yw1-x1149.google.com [IPv6:2607:f8b0:4864:20::1149]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9471CFB for ; Sun, 26 Nov 2023 08:04:27 -0800 (PST) Received: by mail-yw1-x1149.google.com with SMTP id 00721157ae682-5cd6a86a898so37062127b3.3 for ; Sun, 26 Nov 2023 08:04:27 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1701014667; x=1701619467; darn=vger.kernel.org; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=jAcVnKA6iADA9vLnhJjfNDjx1x+ezMFBfqAWXzVOUug=; b=qxpCeGJLfF1BCtxowMWAsfvRVIv/6qZrnIrK/Xl5809mDWHNzkIX7uE999sOckKP79 DN2Purd3BvPqXnrl6nFdfvZ6cWbSFnbAzz6T1SLRYaOqrv/LSKAdNO2Z7SqVe5aN8KEO TWLG6Wo0k4O7deHKhrgrhWmdq65QJwd0Kqotz6lDgxZXs4dwrDRierRwYIQNEGQGInuq YGYjpssDOzVLRN7U1LYM0ZRfIZiYLQbu8jAtqoc2qFzaG7+oOTdSYNIseyyqLUlxvZfr TjvQOSxdZ1hxh9pznfRok2ZZ65iTbpznhZ4QTcKvo0Pjjbja3Ivzolj9OI87B0yP4coL GU/A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1701014667; x=1701619467; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=jAcVnKA6iADA9vLnhJjfNDjx1x+ezMFBfqAWXzVOUug=; b=gO1IV91rzMwwcLzNkc8lw49IorDDZZk5MYvGTbdHcqMTPJ+3IToPmU8QLTfmd7rv7y BTOjSuX/dW4ajbRDKoG3Wl6F89JbvnXCJvk65DoQ+l1D3hpFsoscp5AwqXz0UdviLQbN ZGOLzjyfgZUEfeRUHr1XH4pEAI1AuQ6JkjIWXVMVTGkIQFQ5ymJ4AWxluhh3zdgxSq3i leWJZUXyCyihQeWscUkGYU/YribbKDQKVI9VOBAQZI5iTANz/H2OTv9gYcqeeVoiO5U/ K5TW6TahVN5Z8lYLitbub55VVKHWW1Oc2lmJT6SRfoRRY6o1s37twLKKDoJhGj3/jqK4 0XKQ== X-Gm-Message-State: AOJu0YxazooANWB8jxiRc7K9qP7ful+PwnMKUwCOoHUHp+if2arInxyU X8aYRwqJIY5JlP6FDBsRjZ1ZdipKddodk8bOoXd7 X-Google-Smtp-Source: AGHT+IH7cSvAl+dD9EIaxrdjmVvg/Xxrak/8orkiMKrBN+wcdRVvxz+40ZTE5uo29YN8WI2xwKeM0LN6CAvXzZhldwne X-Received: from vamshig51.c.googlers.com ([fda3:e722:ac3:cc00:3:22c1:c0a8:70c]) (user=vamshigajjela job=sendgmr) by 2002:a81:9b10:0:b0:5ca:5fcd:7063 with SMTP id s16-20020a819b10000000b005ca5fcd7063mr318515ywg.3.1701014666758; Sun, 26 Nov 2023 08:04:26 -0800 (PST) Date: Sun, 26 Nov 2023 21:34:20 +0530 Mime-Version: 1.0 X-Mailer: git-send-email 2.43.0.rc1.413.gea7ed67945-goog Message-ID: <20231126160420.2442330-1-vamshigajjela@google.com> Subject: [PATCH] serial: 8250_dw: Decouple DLF register check from UCV From: Vamshi Gajjela To: Jiri Slaby , ilpo.jarvinen@linux.intel.com, Andy Shevchenko Cc: Greg Kroah-Hartman , linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, manugautam@google.com, Subhash Jadavani , Vamshi Gajjela Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Designware UART has an optional feature to enable Fractional Baud Rate Divisor (DLF) through the FRACTIONAL_BAUD_DIVISOR_EN configuration parameter, and it is not dependent on ADDITIONAL_FEATURES. dw8250_setup_port() checks DLF to determine dlf_size only when UART Component Version (UCV) is non-zero. As mentioned above DLF and UCV are independent features. Move the logic corresponding to DLF size calculation ahead of the UCV check to prevent early return. Otherwise, dlf_size will be zero and driver will not be able to use the controller's fractional baud rate divisor (DLF) feature. Signed-off-by: Vamshi Gajjela --- drivers/tty/serial/8250/8250_dwlib.c | 22 +++++++++++----------- 1 file changed, 11 insertions(+), 11 deletions(-) diff --git a/drivers/tty/serial/8250/8250_dwlib.c b/drivers/tty/serial/8250= /8250_dwlib.c index 84843e204a5e..136ad093c5b6 100644 --- a/drivers/tty/serial/8250/8250_dwlib.c +++ b/drivers/tty/serial/8250/8250_dwlib.c @@ -259,17 +259,6 @@ void dw8250_setup_port(struct uart_port *p) } up->capabilities |=3D UART_CAP_NOTEMT; =20 - /* - * If the Component Version Register returns zero, we know that - * ADDITIONAL_FEATURES are not enabled. No need to go any further. - */ - reg =3D dw8250_readl_ext(p, DW_UART_UCV); - if (!reg) - return; - - dev_dbg(p->dev, "Designware UART version %c.%c%c\n", - (reg >> 24) & 0xff, (reg >> 16) & 0xff, (reg >> 8) & 0xff); - /* Preserve value written by firmware or bootloader */ old_dlf =3D dw8250_readl_ext(p, DW_UART_DLF); dw8250_writel_ext(p, DW_UART_DLF, ~0U); @@ -282,6 +271,17 @@ void dw8250_setup_port(struct uart_port *p) p->set_divisor =3D dw8250_set_divisor; } =20 + /* + * If the Component Version Register returns zero, we know that + * ADDITIONAL_FEATURES are not enabled. No need to go any further. + */ + reg =3D dw8250_readl_ext(p, DW_UART_UCV); + if (!reg) + return; + + dev_dbg(p->dev, "Designware UART version %c.%c%c\n", + (reg >> 24) & 0xff, (reg >> 16) & 0xff, (reg >> 8) & 0xff); + reg =3D dw8250_readl_ext(p, DW_UART_CPR); if (!reg) { reg =3D data->pdata->cpr_val; --=20 2.43.0.rc1.413.gea7ed67945-goog