Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757051AbaLKKjd (ORCPT ); Thu, 11 Dec 2014 05:39:33 -0500 Received: from foss-mx-na.foss.arm.com ([217.140.108.86]:48040 "EHLO foss-mx-na.foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751514AbaLKKjc (ORCPT ); Thu, 11 Dec 2014 05:39:32 -0500 Date: Thu, 11 Dec 2014 10:39:20 +0000 From: Will Deacon To: Philipp Zabel Cc: Abhilash Kesavan , Santosh Shilimkar , Catalin Marinas , "heiko@sntech.de" , "Li.Xiubo@freescale.com" , "shc_work@mail.ru" , "nicoleotsuka@gmail.com" , "arnd@arndb.de" , "gregkh@linuxfoundation.org" , "robh+dt@kernel.org" , "grant.likely@linaro.org" , "linux-kernel@vger.kernel.org" , "corbet@lwn.net" , "padma.v@samsung.com" , "alsa-devel@alsa-project.org" , "shawn.guo@freescale.com" , "bcousson@baylibre.com" , "tony@atomide.com" , "kernel@pengutronix.de" , "kgene@kernel.org" , "kesavan.abhilash@gmail.com" , Pawel Moll Subject: Re: [PATCH 2/2] misc: sram: switch to ioremap_wc from ioremap Message-ID: <20141211103919.GA6067@arm.com> References: <1418266726-12004-1-git-send-email-a.kesavan@samsung.com> <1418266726-12004-2-git-send-email-a.kesavan@samsung.com> <1418292513.3188.4.camel@pengutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1418292513.3188.4.camel@pengutronix.de> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Dec 11, 2014 at 10:08:33AM +0000, Philipp Zabel wrote: > Hi Abhilash, > > Am Donnerstag, den 11.12.2014, 08:28 +0530 schrieb Abhilash Kesavan: > > Currently, the SRAM allocator returns device memory via ioremap. > > This causes issues on ARM64 when the internal SoC SRAM allocated by > > the generic sram driver is used for audio playback. The destination > > buffer address (which is ioremapped SRAM) is not 64-bit aligned for > > certain streams (e.g. 44.1k sampling rate). In such cases we get > > unhandled alignment faults. Use ioremap_wc in place of ioremap which > > gives us normal non-cacheable memory instead of device memory. > > Could this break the omap_bus_sync() implementation in > arch/arm/mach-omap2/omap4-common.c? > > void omap_bus_sync(void) > { > if (dram_sync && sram_sync) { > writel_relaxed(readl_relaxed(dram_sync), dram_sync); > writel_relaxed(readl_relaxed(sram_sync), sram_sync); > isb(); > } > } > > It is used in wmb() and omap_do_wfi() to drain interconnect write > buffers on omap4/5. If sram_sync is mapped with write-combining, could > the last write to sram_sync stay stuck in the write-combining buffer > until after the function returns? I think you have that issue anyway, since you can get an early write response even if you use ioremap. Does the write to sram_sync have side-effects that we need to wait for? Will -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/