From patchwork Fri Mar 27 14:59:30 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Dave Martin X-Patchwork-Id: 455435 Return-Path: X-Original-To: incoming-imx@patchwork.ozlabs.org Delivered-To: patchwork-incoming-imx@bilbo.ozlabs.org Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2001:1868:205::9]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 37B881400B6 for ; Sat, 28 Mar 2015 02:03:30 +1100 (AEDT) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1YbVlA-0005iR-8K; Fri, 27 Mar 2015 15:01:20 +0000 Received: from eu-smtp-delivery-143.mimecast.com ([207.82.80.143]) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1YbVkK-0004Il-9r for linux-arm-kernel@lists.infradead.org; Fri, 27 Mar 2015 15:00:30 +0000 Received: from cam-owa1.Emea.Arm.com (fw-tnat.cambridge.arm.com [217.140.96.140]) by uk-mta-2.uk.mimecast.lan; Fri, 27 Mar 2015 15:00:02 +0000 Received: from e103592.cambridge.arm.com ([10.1.2.79]) by cam-owa1.Emea.Arm.com with Microsoft SMTPSVC(6.0.3790.3959); Fri, 27 Mar 2015 15:00:00 +0000 From: Dave Martin To: linux-serial@vger.kernel.org Subject: [PATCH v4 1/2] Revert "serial/amba-pl011: Leave the TX IRQ alone when the UART is not open" Date: Fri, 27 Mar 2015 14:59:30 +0000 Message-Id: <1427468371-11915-2-git-send-email-Dave.Martin@arm.com> X-Mailer: git-send-email 1.7.10.4 In-Reply-To: <1427468371-11915-1-git-send-email-Dave.Martin@arm.com> References: <1427468371-11915-1-git-send-email-Dave.Martin@arm.com> MIME-Version: 1.0 X-OriginalArrivalTime: 27 Mar 2015 15:00:01.0060 (UTC) FILETIME=[B2FA1640:01D0689E] X-MC-Unique: kgLjVLjeQd-M6iSezRqCLQ-1 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20150327_080028_676973_B86FCC72 X-CRM114-Status: GOOD ( 10.20 ) X-Spam-Score: -2.3 (--) X-Spam-Report: SpamAssassin version 3.4.0 on bombadil.infradead.org summary: Content analysis details: (-2.3 points) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_MSPIKE_H3 RBL: Good reputation (+3) [207.82.80.143 listed in wl.mailspike.net] -2.3 RCVD_IN_DNSWL_MED RBL: Sender listed at http://www.dnswl.org/, medium trust [207.82.80.143 listed in list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record -0.0 RCVD_IN_MSPIKE_WL Mailspike good senders Cc: Russell King , =?UTF-8?q?Jakub=20Kici=C5=84ski?= , Greg Kroah-Hartman , Andrew Jackson , Graeme Gregory , Andre Przywara , popcorn mix , Jorge Ramirez-Ortiz , linux-arm-kernel@lists.infradead.org X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+incoming-imx=patchwork.ozlabs.org@lists.infradead.org List-Id: linux-imx-kernel.lists.patchwork.ozlabs.org This reverts commit f2ee6dfa0e8597eea8b98d240b0033994e20d215. Jakub Kiciński observed that this patch can cause the pl011 driver to hang if if the only process with a pl011 port open is killed by a signal, pl011_shutdown() can get called with an arbitrary amount of data still in the FIFO. Calling _shutdown() with the TX FIFO non-empty is questionable behaviour and my itself be a bug. Since the affected patch was speculative anyway, and brings limited benefit, the simplest course is to remove the assumption that TXIS will always be left asserted after the port is shut down. Signed-off-by: Dave Martin --- drivers/tty/serial/amba-pl011.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c index 5a4e9d5..6f5a072 100644 --- a/drivers/tty/serial/amba-pl011.c +++ b/drivers/tty/serial/amba-pl011.c @@ -1639,6 +1639,9 @@ static int pl011_startup(struct uart_port *port) writew(uap->vendor->ifls, uap->port.membase + UART011_IFLS); + /* Assume that TX IRQ doesn't work until we see one: */ + uap->tx_irq_seen = 0; + spin_lock_irq(&uap->port.lock); /* restore RTS and DTR */ @@ -1702,7 +1705,7 @@ static void pl011_shutdown(struct uart_port *port) spin_lock_irq(&uap->port.lock); uap->im = 0; writew(uap->im, uap->port.membase + UART011_IMSC); - writew(0xffff & ~UART011_TXIS, uap->port.membase + UART011_ICR); + writew(0xffff, uap->port.membase + UART011_ICR); spin_unlock_irq(&uap->port.lock); pl011_dma_shutdown(uap);