From patchwork Mon Oct 4 14:39:36 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Sripathy, Vishwanath" X-Patchwork-Id: 228541 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by demeter1.kernel.org (8.14.4/8.14.3) with ESMTP id o94HOq1A004239 for ; Mon, 4 Oct 2010 17:25:01 GMT Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756080Ab0JDOl6 (ORCPT ); Mon, 4 Oct 2010 10:41:58 -0400 Received: from devils.ext.ti.com ([198.47.26.153]:51823 "EHLO devils.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751670Ab0JDOl6 (ORCPT ); Mon, 4 Oct 2010 10:41:58 -0400 Received: from dbdp31.itg.ti.com ([172.24.170.98]) by devils.ext.ti.com (8.13.7/8.13.7) with ESMTP id o94Efrbn028690 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Mon, 4 Oct 2010 09:41:56 -0500 Received: from localhost.localdomain (localhost [127.0.0.1]) by dbdp31.itg.ti.com (8.13.8/8.13.8) with ESMTP id o94EfpJm023640; Mon, 4 Oct 2010 20:11:52 +0530 (IST) From: Vishwanath BS To: linux-omap@vger.kernel.org Cc: Vishwanath BS , Paul Walmsley Subject: [PATCH] OMAP3: SDRC : Add comments on Errata i520 for Global SW reset Date: Mon, 4 Oct 2010 20:09:36 +0530 Message-Id: <1286203176-32602-1-git-send-email-vishwanath.bs@ti.com> X-Mailer: git-send-email 1.7.0.4 Sender: linux-omap-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-omap@vger.kernel.org X-Greylist: IP, sender and recipient auto-whitelisted, not delayed by milter-greylist-4.2.3 (demeter1.kernel.org [140.211.167.41]); Mon, 04 Oct 2010 17:25:01 +0000 (UTC) diff --git a/arch/arm/mach-omap2/prcm.c b/arch/arm/mach-omap2/prcm.c index c201374..fdc860e --- a/arch/arm/mach-omap2/prcm.c +++ b/arch/arm/mach-omap2/prcm.c @@ -157,6 +157,32 @@ void omap_prcm_arch_reset(char mode, const char *cmd) else WARN_ON(1); + /* As per Errata i520, In some cases, user + * will not be able to access DDR memory after warm-reset. + * This situation occurs while the warm-reset happens during a read + * access to DDR memory. In that particular condition, DDR memory + * does not respond to a corrupted read command due to the warm + * reset occurence but SDRC is waiting for read completion. + * SDRC is not sensitive to the warm reset, but the interconect is + * reset on the fly, thus causing a misalignment between SDRC logic, + * interconect logic and DDR memory state. + * WORKAROUND: + * Steps to perform before a Warm reset is trigged: + * 1. enable self-refresh on idle request + * 2. put SDRC in idle + * 3. wait until SDRC goes to idle + * 4. generate SW reset (Global SW reset) + + * Steps to be performed after warm reset occurs (in bootloader): + * if HW warm reset is the source, apply below steps before any + * accesses to SDRAM: + * 1. Reset SMS and SDRC and wait till reset is complete + * 2. Re-initialize SMS, SDRC and memory + + * NOTE: Above work around is required only if arch reset is implemented + * using Global SW reset(GLOBAL_SW_RST). DPLL3 reset does not need + * the WA since it resets SDRC as well as part of cold reset. */ + if (cpu_is_omap24xx() || cpu_is_omap34xx()) prm_set_mod_reg_bits(OMAP_RST_DPLL3_MASK, prcm_offs, OMAP2_RM_RSTCTRL);