From patchwork Tue Mar 7 22:26:48 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Martin Blumenstingl X-Patchwork-Id: 13164856 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 2CA71C678D5 for ; Tue, 7 Mar 2023 22:28:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:Message-Id:Date:Subject:Cc :To:From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References: List-Owner; bh=Vj/aDngaXluLJKG8VUvX+ToLmIgKOhG4I5JlCrjnQ6k=; b=chYdWey6/cMViC p+MfUrsv5zGoXPzfhOSm1kaPB7NoAMv6vfconiFFvwpYNGTXqQkM+wnfaTpCBJLMN4QkhmQOZ6uOp q+Jv3qdR7M85RrAd/44cBxdabfF7RjRtkSQgXZjC6UFtaA8yZ4hwCLho+WbvE75aq5FUaxQTF5R5/ pQmq9OEcx5l2YOvHY/m6WjUsXLrM6oVTlKQ1Zv/CWzBb8lxMPenPkXfKUMIRSRQ8FHtp12AC6x0+3 9Drtuiv8HpaUqs0g4Wjg8tqKPPhTxufq8184LMYsoZ0/9WxC8C68ML7STi85IonfzUa43nNc1l6sY r5jLuoQ2CxpQqlWtUc+w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1pZfmH-002f6v-6g; Tue, 07 Mar 2023 22:27:25 +0000 Received: from mail-ed1-x529.google.com ([2a00:1450:4864:20::529]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1pZflx-002ezt-DJ; Tue, 07 Mar 2023 22:27:08 +0000 Received: by mail-ed1-x529.google.com with SMTP id j11so38954654edq.4; Tue, 07 Mar 2023 14:27:03 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=googlemail.com; s=20210112; t=1678228021; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=8gjcCprh0YtfA6Dnk0t8C1b7TfZOQ0dz/8SnTGInkFw=; b=GX5tKBTUsIR1Y3f5WlAlOygrvh+AjgsTKfFdsV7j8TjOfzu0KDs1huN4yai3/K4+xV lLuyCyS4mhgtbXMUf/mhycv6ttOCbPvsWfDL/+Jq39lzsmsvVJTfNSmjEhzEkBzxO1JC +KgOysHLqNB4zgqjqI/XypqKidEGESmCUr7CklJsULGF5bugnyfUpgLbi5KKoYalOMuo X9kSmaV+RWFZ4SzjBhzWpA8Om5u/CQ8T2kgwUz5nH20C1zEMMzALEq9oA4po/+CUKDrE S8KrBg6/NB6KsnPkxR1nmTEgoOkLzCwvW441q825numITyeG8TGOM/9qVwoBq3xa1FfP KdKg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1678228021; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=8gjcCprh0YtfA6Dnk0t8C1b7TfZOQ0dz/8SnTGInkFw=; b=79bvaYlZ0sK8Fheg/O8VHUR0EjgPV9cfdblLQG8L/PDt4duxRCMnd7lDszwCjLh1wy 8wCWCTiM0pUbFlZ/nXjevepTswDnl+xq4czUnKW6NMJbQ8sl2LGzGw1Pvg/fdgpN8XU5 0rV60VdIvSkMOheQrqKBTlkGM9EKYet4049Pch6GnZDNYDzQHspKD1mFlbb7a34pYOlA R/bgRu+3H/lsW2arqk3dQAEJ75bIK9SEjswN4rgfldUp8CNycaJloK30AHMicH+3pzb+ SR4/j5ISMhotMBFhcel9PxFbRmPOL1s+d0O4ly7AOz4Dm5dxkkDrpV/ONHQWkPoa/bPM SIHQ== X-Gm-Message-State: AO0yUKUsnNUh8h3xt1K+c7kB/md4qZ/xNRuAMvWLkbeGnODSo6MDQDxZ lpjRbebu8B9bPvp4gD09Rq8q9VF45Kg= X-Google-Smtp-Source: AK7set+1wRh2vgznuNAkSHl6cmRUMN6CNrWvNayb33+wDRXF+1iPXKb/NZPh5Uroj+Zs8Mmntku6nQ== X-Received: by 2002:a17:906:dac3:b0:8a9:fa2f:e440 with SMTP id xi3-20020a170906dac300b008a9fa2fe440mr21240590ejb.55.1678228021589; Tue, 07 Mar 2023 14:27:01 -0800 (PST) Received: from localhost.localdomain (dynamic-2a01-0c23-c485-ef00-0000-0000-0000-0e63.c23.pool.telefonica.de. [2a01:c23:c485:ef00::e63]) by smtp.googlemail.com with ESMTPSA id t19-20020a170906065300b008be996c1630sm6669412ejb.39.2023.03.07.14.27.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 07 Mar 2023 14:27:01 -0800 (PST) From: Martin Blumenstingl To: linux-amlogic@lists.infradead.org, devicetree@vger.kernel.org Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, jirislaby@kernel.org, neil.armstrong@linaro.org, krzysztof.kozlowski+dt@linaro.org, robh+dt@kernel.org, gregkh@linuxfoundation.org, Christian Hewitt , Martin Blumenstingl Subject: [PATCH v3 0/3] meson-uart: Use "divide XTAL by 2" bit on G12A Date: Tue, 7 Mar 2023 23:26:48 +0100 Message-Id: <20230307222651.2106615-1-martin.blumenstingl@googlemail.com> X-Mailer: git-send-email 2.39.2 MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230307_142705_476008_B0C3ED0C X-CRM114-Status: GOOD ( 12.58 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org This series improves support for UART attached Bluetooth modules on Amlogic Meson G12A and newer SoCs. These SoCs also support the "divide XTAL by 2" bit which (greatly) reduces jitter when generating baud rates such as 1500000 (which is used by the Bluetooth part of the RTL8822CS SDIO WiFi and UART Bluetooth combo chip). Without this the baud rate calculation is based on the XTAL clock (running at 24MHz) divided by 3 (meaning: 8MHz). 8MHz cannot be divided with integer division to a 1500000 baud rate. Using the "divide XTAL by 2" bit however means that we can achieve 1500000 cleanly, without any jitter. In future we should allow dynamic switching of these UART controller internal dividers to pick the best divider automatically for the requested baud rate. This however still requires the new compatible string - which is added by this series - to enable the "divide XTAL by 2" logic on SoCs that support it (G12A and newer). Changes since v1 at [1]: - make meson-gx-uart a valid fallback compatible string for the newer meson-g12a-uart - rebased on top of v6.3-rc1 Changes since v2 at [2]: - simplify the dt-bindings patch as suggested by Krzysztof Kozlowski (thank you!) which actually uncovers an unwanted change [0] https://lore.kernel.org/linux-bluetooth/3B9D4DB2-D2CD-44FE-817A-F6EA8A0AD734@gmail.com/ [1] https://lore.kernel.org/lkml/20230222210425.626474-1-martin.blumenstingl@googlemail.com/ [2] https://lore.kernel.org/lkml/20230306194223.1869814-1-martin.blumenstingl@googlemail.com/ Martin Blumenstingl (3): dt-bindings: serial: amlogic,meson-uart: Add compatible string for G12A tty: serial: meson: Add a new compatible string for the G12A SoC arm64: dts: meson-g12-common: Use the G12A UART compatible string .../bindings/serial/amlogic,meson-uart.yaml | 9 +++++++++ arch/arm64/boot/dts/amlogic/meson-g12-common.dtsi | 15 ++++++++++----- drivers/tty/serial/meson_uart.c | 8 ++++++-- 3 files changed, 25 insertions(+), 7 deletions(-)