From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935074AbcHJUT1 (ORCPT ); Wed, 10 Aug 2016 16:19:27 -0400 Received: from mail-qt0-f179.google.com ([209.85.216.179]:33131 "EHLO mail-qt0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932481AbcHJSZq (ORCPT ); Wed, 10 Aug 2016 14:25:46 -0400 MIME-Version: 1.0 In-Reply-To: <57AB4B43.2010705@redhat.com> References: <20160810032613.GA25053@mtj.duckdns.org> <20160810151447.GI25053@mtj.duckdns.org> <57AB4B43.2010705@redhat.com> From: Tom Yan Date: Wed, 10 Aug 2016 17:19:51 +0000 Message-ID: Subject: Re: Regarding AHCI_MAX_SG and (ATA_HORKAGE_MAX_SEC_1024) To: David Milburn Cc: Tejun Heo , linux-ide@vger.kernel.org, linux-scsi@vger.kernel.org, linux-block@vger.kernel.org, LKML Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10 August 2016 at 15:41, David Milburn wrote: > Hi, > > The 168 makes AHCI_CMD_TBL_SZ equal to 2816 > > AHCI_CMD_TBL_SZ = AHCI_CMD_TBL_HDR_SZ + (AHCI_MAX_SG * 16) > AHCI_CMD_TBL_SZ = 128 + (168 * 16) > > I think if you add in AHCI_CMD_SLOT_SZ (1024) and AHCI_RX_FIS_SZ (256) > the DMA is 4K aligned, I think that is where the 168 came from. Looks like the right guess. Though AHCI_PORT_PRIV_DMA_SZ is not: AHCI_CMD_SLOT_SZ (1024) + AHCI_CMD_TBL_SZ (2816) + AHCI_RX_FIS_SZ (256) = 4096 but: AHCI_CMD_SLOT_SZ (1024) + AHCI_CMD_TBL_AR_SZ (2816 * 32 = 90112) + AHCI_RX_FIS_SZ (256) = 91392 and AHCI_PORT_PRIV_FBS_DMA_SZ is: AHCI_CMD_SLOT_SZ (1024) + AHCI_CMD_TBL_AR_SZ (2816 * 32 = 90112) + AHCI_RX_FIS_SZ * 16 (4096) = 95232 > > Thanks, > David > >