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x-vs=clean score=0 state=0 X-ME-VSCategory: clean X-CM-Envelope: MS4wfD5Lg6uTHnZvUr5i0eHtp5sYqTmuiYf5TE4x56dFYRYlBlOxKZ/1+i8Wq0f8A2QD5R1WA3+Eo5Q7CTIAqQkj9xhEI5gAMBKyVD0Dzd+hAc43KRFnP1O6 fLD0/3bXaWZ6uJvqb1Wr5zAKwzowpCB4C2xkY9DEOMC8kL5VbvSvcrnFTON4IYpzOEMfkLfEu0tfvX6njllkgFXAnvO/Pty+sjFrL3IuzYixGO2H1cyo82OJ X-CM-Analysis: v=2.3 cv=FKU1Odgs c=1 sm=1 tr=0 a=UK1r566ZdBxH71SXbqIOeA==:117 a=UK1r566ZdBxH71SXbqIOeA==:17 a=IkcTkHD0fZMA:10 a=xqWC_Br6kY4A:10 a=Kd1tUaAdevIA:10 a=8AirrxEcAAAA:8 a=VwQbUJbxAAAA:8 a=IoFmlQYEO8KAc7pQ7V0A:9 a=QEXdDO2ut3YA:10 a=x8gzFH9gYPwA:10 a=ST-jHhOKWsTCqRlWije3:22 a=AjGcO6oz07-iQ99wixmX:22 X-ME-CMScore: 0 X-ME-CMCategory: none Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754786AbeDTMoO (ORCPT ); Fri, 20 Apr 2018 08:44:14 -0400 Received: from mail.kmu-office.ch ([178.209.48.109]:60670 "EHLO mail.kmu-office.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754712AbeDTMoM (ORCPT ); Fri, 20 Apr 2018 08:44:12 -0400 From: Stefan Agner To: gregkh@linuxfoundation.org Cc: u.kleine-koenig@pengutronix.de, festevam@gmail.com, jslaby@suse.com, linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, Stefan Agner Subject: [PATCH v2] serial: imx: fix cached UCR2 read on software reset Date: Fri, 20 Apr 2018 14:44:07 +0200 Message-Id: <20180420124407.12892-1-stefan@agner.ch> X-Mailer: git-send-email 2.17.0 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Remote-Spamd-Result: default: False [-2.10 / 15.00]; RCVD_TLS_ALL(0.00)[]; ASN(0.00)[asn:13030, ipnet:2001:1620::/32, country:CH]; RCVD_COUNT_ZERO(0.00)[0]; FROM_HAS_DN(0.00)[]; MID_CONTAINS_FROM(1.00)[]; TO_DN_SOME(0.00)[]; MIME_GOOD(-0.10)[text/plain]; FROM_EQ_ENVFROM(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; BAYES_HAM(-3.00)[100.00%]; ARC_NA(0.00)[]; DKIM_SIGNED(0.00)[]; RCPT_COUNT_SEVEN(0.00)[7] Sender: linux-serial-owner@vger.kernel.org X-Mailing-List: linux-serial@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: To reset the UART the SRST needs be cleared (low active). According to the documentation the bit will remain active for 4 module clocks until it is cleared (set to 1). Hence the real register need to be read in case the cached register indicates that the SRST bit is zero. This bug lead to wrong baudrate because the baud rate register got restored before reset completed in imx_flush_buffer. Fixes: 3a0ab62f43de ("serial: imx: implement shadow registers for UCRx and UFCR") Signed-off-by: Stefan Agner Reviewed-by: Fabio Estevam Reviewed-by: Uwe Kleine-König --- Hi Greg, Since this fixes a regression it should go into v4.17... -- Stefan drivers/tty/serial/imx.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c index 91f3a1a5cb7f..4ff6bd6eb9ab 100644 --- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -316,7 +316,7 @@ static u32 imx_uart_readl(struct imx_port *sport, u32 offset) * differ from the value that was last written. As it only * clears after being set, reread conditionally. */ - if (sport->ucr2 & UCR2_SRST) + if (!(sport->ucr2 & UCR2_SRST)) sport->ucr2 = readl(sport->port.membase + offset); return sport->ucr2; break; -- 2.17.0