From patchwork Thu May 20 02:13:32 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Jeffery X-Patchwork-Id: 443748 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2B90DC433ED for ; Thu, 20 May 2021 02:14:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0B134611BF for ; Thu, 20 May 2021 02:14:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230315AbhETCQK (ORCPT ); Wed, 19 May 2021 22:16:10 -0400 Received: from new1-smtp.messagingengine.com ([66.111.4.221]:34237 "EHLO new1-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230308AbhETCPu (ORCPT ); Wed, 19 May 2021 22:15:50 -0400 Received: from compute2.internal (compute2.nyi.internal [10.202.2.42]) by mailnew.nyi.internal (Postfix) with ESMTP id ACA925808EB; Wed, 19 May 2021 22:13:49 -0400 (EDT) Received: from mailfrontend2 ([10.202.2.163]) by compute2.internal (MEProxy); Wed, 19 May 2021 22:13:49 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=aj.id.au; h=from :to:cc:subject:date:message-id:mime-version :content-transfer-encoding; s=fm2; bh=odecAKUaHKQG4X3qJBH558YiNF 7tYkLnTOKSXP3atJM=; b=TBAjCkk+uY2vL+OPwD/lYfZ9Qd6hy31ihSr8xd0dER PAhQvk5iYF7YH9Yvo8H2rOcZGIc+JjioT2xksAA+5QM6/HRC2xe94VBjExBy/FhF MGqjFe0RWKq60dai30WXXqO4IsJXrc34UIvxcctz9BqHbDSLzX2pzkgILvtmvjDQ b2k8t2xr6ZQTQ+wb23M2rYocYszl5wjFwXC9feT0j9PDvdwFoYJE0ARQGoHitZNL idcfpvX5BO1Ai500+DqKTMofPg+IPjidnX6VcyeHc6T+Xt2wvZNnQ/tNzo4yHFkK RM8vQUUax0XWYWW4VVQYN9JDDZCmJg85nJW5ag3eHIqw== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-transfer-encoding:date:from :message-id:mime-version:subject:to:x-me-proxy:x-me-proxy :x-me-sender:x-me-sender:x-sasl-enc; s=fm2; bh=odecAKUaHKQG4X3qJ BH558YiNF7tYkLnTOKSXP3atJM=; b=ajPVZwIRN8x1f044hZZ78SjOdzZ2dcid7 4O6D8HV1KWmQxN+3WPnvpC0HCqGiV4QRKIsofQhNldfU/IZJFNQ0HroscZdCsjtI 21SuRslEESk2tql30Hb2Ryu8Y54iI0JaOEW9y0mu9VC7oL68I/4++1XEifSKRTyi tAVkRR2lEJh7O5Ldk+q46JxM8DF/+yPv/k53jlg7rJflyJN8ckBrI49tZAo+AjnQ KH5jL39tibMDPP5TANRlf1IFKXi2HOqnuGQW/K8PCioBUD797wBgVF9ttEy0CFI3 FW3RdwTvQNBqrP7N758PDBV/moyULfKMQ0yQRv2QDuj8tmJxuCSUw== X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeduledrvdejtddgheeiucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucenucfjughrpefhvffufffkofgggfestdekredtre dttdenucfhrhhomheptehnughrvgifucflvghffhgvrhihuceorghnughrvgifsegrjhdr ihgurdgruheqnecuggftrfgrthhtvghrnhepieetheduveelhfdvvdejleeuhfelteevhe ffgfeitdefgeekjeefieevgfehhefgnecuffhomhgrihhnpehkvghrnhgvlhdrohhrghen ucfkphepvddtfedrheejrddvudehrdeknecuvehluhhsthgvrhfuihiivgeptdenucfrrg hrrghmpehmrghilhhfrhhomheprghnughrvgifsegrjhdrihgurdgruh X-ME-Proxy: Received: from mistburn.lan (203-57-215-8.dyn.iinet.net.au [203.57.215.8]) by mail.messagingengine.com (Postfix) with ESMTPA; Wed, 19 May 2021 22:13:43 -0400 (EDT) From: Andrew Jeffery To: linux-serial@vger.kernel.org Cc: gregkh@linuxfoundation.org, jirislaby@kernel.org, joel@jms.id.au, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-aspeed@lists.ozlabs.org, openbmc@lists.ozlabs.org, jenmin_yuan@aspeedtech.com, ryan_chen@aspeedtech.com, miltonm@us.ibm.com Subject: [PATCH v3 0/2] serial: 8250: Mitigate Tx stall risk for Aspeed VUARTs Date: Thu, 20 May 2021 11:43:32 +0930 Message-Id: <20210520021334.497341-1-andrew@aj.id.au> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org Hello, Briefly, the series works around a hardware race condition in the Tx path for Aspeed virtual UARTs. A write burst to THR on the APB interface may provoke a transfer stall where LSR[DR] on the LPC interface remains clear despite the presence of data in the Rx FIFO. v3 addresses comments from Jiri on v2. v2 can be found here: https://lore.kernel.org/lkml/20210519000704.3661773-1-andrew@aj.id.au/ The documentation patch that fell out of the discussion of patch 2 of v2 can be found here: https://lore.kernel.org/lkml/20210520015704.489737-1-andrew@aj.id.au/T/#u Please review! Andrew Andrew Jeffery (2): serial: 8250: Add UART_BUG_TXRACE workaround for Aspeed VUART serial: 8250: Use BIT(x) for UART_{CAP,BUG}_* drivers/tty/serial/8250/8250.h | 32 +++++++++++---------- drivers/tty/serial/8250/8250_aspeed_vuart.c | 1 + drivers/tty/serial/8250/8250_port.c | 12 ++++++++ 3 files changed, 30 insertions(+), 15 deletions(-) Reviewed-by: Jiri Slaby