From mboxrd@z Thu Jan 1 00:00:00 1970 From: Loic Poulain Subject: Re: [PATCH] serial: 8250_dw: Handle no_console_suspend when uart loses state Date: Mon, 17 Nov 2014 09:56:08 +0100 Message-ID: <5469B828.90401@intel.com> References: <1416011556-23422-1-git-send-email-dianders@chromium.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mga11.intel.com ([192.55.52.93]:53677 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751625AbaKQIx2 (ORCPT ); Mon, 17 Nov 2014 03:53:28 -0500 In-Reply-To: <1416011556-23422-1-git-send-email-dianders@chromium.org> Sender: linux-serial-owner@vger.kernel.org List-Id: linux-serial@vger.kernel.org To: Doug Anderson Cc: Greg Kroah-Hartman , Heiko Stuebner , Jiri Slaby , Chris Zhong , linux-rockchip@lists.infradead.org, linux-arm-kernel@lists.infradead.org, Andrew Bresticker , mika.westerberg@linux.intel.com, heikki.krogerus@linux.intel.com, andriy.shevchenko@linux.intel.com, wens@csie.org, alan@linux.intel.com, linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org > In certain suspend modes on certain boards the 8250 UART may lose > state when the device goes to suspend. If we're using > no_console_suspend this can cause lots of problems during resume. > > Let's cache the basic UART config registers at suspend time and if we > notice that the UART loses state (by looking at a canary stored in the > scratch register) we'll restore it. If I'm not wrong, it's already done in acpi_lpss suspend/resume (for 8250_dw). Commit c78b0830667a7e7c1f0ca65b76b33166a84806b3. Regards, Loic -- Intel Open Source Technology Center http://oss.intel.com/