From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Ball Subject: Re: [PATCH v9] mmc: support BKOPS feature for eMMC Date: Sun, 08 Jul 2012 22:48:54 -0400 Message-ID: <87vchxvecp.fsf@octavius.laptop.org> References: <4FD1821D.4070603@samsung.com> <874npkx2dq.fsf@octavius.laptop.org> <4FFA4334.7010904@samsung.com> Mime-Version: 1.0 Content-Type: text/plain Return-path: Received: from void.printf.net ([89.145.121.20]:43514 "EHLO void.printf.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751419Ab2GICtJ (ORCPT ); Sun, 8 Jul 2012 22:49:09 -0400 In-Reply-To: <4FFA4334.7010904@samsung.com> (Jaehoon Chung's message of "Mon, 09 Jul 2012 11:34:28 +0900") Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: Jaehoon Chung Cc: merez@codeaurora.org, linux-mmc , Kyungmin Park , Hanumath Prasad , Per FORLIN , Sebastian Rasmussen , "Dong, Chuanxiao" , "svenkatr@ti.com" , Saugata Das , Konstantin Dorfman , Adrian Hunter , Ulf Hansson Hi, On Sun, Jul 08 2012, Jaehoon Chung wrote: >> I think MMC_CAP2_BKOPS should be removed. If the card BKOPs were already >> enabled, the host must support BKOPs. Therefore, in mmc_start_bkops we >> should check only if card->ext_csd.bkops_en is set. > > If bkops bit is set, it means that use the bkops by default. > If somebody didn't want to use the bkops, then just didn't set the MMC_CAP2_BKOPS. > And eMMC card's BKOPS bit should not be set, > then we can set the BKOPS support with switch command. > For this, MMC_CAP2_INIT_BKOPS is added. > In my case, didn't set the bkops enable bit at first time. > So need to set bkops enable bit with switch command. > > As Maya's mentioned, if we use the bkops by default, we can remove the MMC_CAP2_BKOPS2. I'm not sure I understand. If someone has advertised MMC_CAP2_BKOPS on their host, why do we also need to check for MMC_CAP2_INIT_BKOPS before we enable it in the ext_csd? Why shouldn't we just use one (MMC_CAP2_BKOPS) capability to mean "enable bkops if supported, by writing 1 (if it wasn't already set) to ext_csd[163] to tell the card that we're going to be using bkops"? Are there any disadvantages to doing this? Thanks, - Chris. -- Chris Ball One Laptop Per Child