From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Lord Subject: [PATCH 03/12] sata_mv wait for empty+idle Date: Fri, 02 May 2008 02:09:14 -0400 Message-ID: <481AB00A.3000206@rtr.ca> References: <481AAF84.40501@rtr.ca> <481AAFB7.4090708@rtr.ca> <481AAFE0.9090101@rtr.ca> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from rtr.ca ([76.10.145.34]:1120 "EHLO mail.rtr.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756370AbYEBGJQ (ORCPT ); Fri, 2 May 2008 02:09:16 -0400 In-Reply-To: <481AAFE0.9090101@rtr.ca> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Jeff Garzik , Tejun Heo , IDE/ATA development list When performing EH, it is recommended to wait for the EDMA engine to empty out requests-in-progress before disabling EDMA. Introduce code to poll the EDMA_STATUS register for idle/empty bits before disabling EDMA. For non-EH operation, this will normally exit without delay, other than the register read. A later series of patches may focus on eliminating this and various other register reads (when possible) throughout the driver, but for now we're focussing on solid reliablity. Signed-off-by: Mark Lord --- old/drivers/ata/sata_mv.c 2008-05-01 17:49:53.000000000 -0400 +++ linux/drivers/ata/sata_mv.c 2008-05-01 17:56:54.000000000 -0400 @@ -888,6 +888,25 @@ } } +static void mv_wait_for_edma_empty_idle(struct ata_port *ap) +{ + void __iomem *port_mmio = mv_ap_base(ap); + const u32 empty_idle = (EDMA_STATUS_CACHE_EMPTY | EDMA_STATUS_IDLE); + const int per_loop = 5, timeout = (15 * 1000 / per_loop); + int i; + + /* + * Wait for the EDMA engine to finish transactions in progress. + */ + for (i = 0; i < timeout; ++i) { + u32 edma_stat = readl(port_mmio + EDMA_STATUS_OFS); + if ((edma_stat & empty_idle) == empty_idle) + break; + udelay(per_loop); + } + /* ata_port_printk(ap, KERN_INFO, "%s: %u+ usecs\n", __func__, i); */ +} + /** * mv_stop_edma_engine - Disable eDMA engine * @port_mmio: io base address @@ -920,6 +939,7 @@ if (!(pp->pp_flags & MV_PP_FLAG_EDMA_EN)) return 0; pp->pp_flags &= ~MV_PP_FLAG_EDMA_EN; + mv_wait_for_edma_empty_idle(ap); if (mv_stop_edma_engine(port_mmio)) { ata_port_printk(ap, KERN_ERR, "Unable to stop eDMA\n"); return -EIO;