From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tony Lindgren Subject: Re: [PATCH 02/25] OMAP4: Redefine mandatory barriers for OMAP to include interconnect barriers. Date: Tue, 13 Sep 2011 13:27:01 -0700 Message-ID: <20110913202701.GF24252@atomide.com> References: <1315144466-9395-1-git-send-email-santosh.shilimkar@ti.com> <1315144466-9395-3-git-send-email-santosh.shilimkar@ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mho-03-ewr.mailhop.org ([204.13.248.66]:53970 "EHLO mho-01-ewr.mailhop.org" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932470Ab1IMU1E (ORCPT ); Tue, 13 Sep 2011 16:27:04 -0400 Content-Disposition: inline In-Reply-To: <1315144466-9395-3-git-send-email-santosh.shilimkar@ti.com> Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Santosh Shilimkar Cc: linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux@arm.linux.org.uk, khilman@ti.com, rnayak@ti.com, Richard Woodruff * Santosh Shilimkar [110904 06:22]: > On OMAP4 SOC intecronnects has many write buffers in the async bridges > and they can be drained only with stongly ordered accesses. This is not correct, strongly ordered access does not guarantee anything here. If it fixes issues, it's because it makes the writes to reach the device faster. Strongly ordered does not affect anything outside ARM, so the bus access won't change. The only real fix here is to do a read back of the device in question to guarantee the write got to the device. > There are two ports as below from MPU and both needs to be drained. > - MPU --> L3 T2ASYNC FIFO > - MPU --> DDR T2ASYNC FIFO > > Without the interconnect barriers, many issues have been observed > leading to system freeze, CPU deadlocks, random crashes with > register accesses, synchronization loss on initiators operating > on both interconnect port simultaneously. We had these issues for omap3 too. Adding a few read backs solved those kinds of issues. Regards, Tony