From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Ball Subject: Re: [PATCH v5] mmc: support BKOPS feature for eMMC Date: Sat, 07 Jan 2012 21:21:29 -0500 Message-ID: References: <4F04F512.1020909@samsung.com> <17296D9F8FF2234F831FC3DF505A87A90FCB43D7@SHSMSX101.ccr.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain Return-path: Received: from void.printf.net ([89.145.121.20]:57880 "EHLO void.printf.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751903Ab2AHCV4 (ORCPT ); Sat, 7 Jan 2012 21:21:56 -0500 In-Reply-To: <17296D9F8FF2234F831FC3DF505A87A90FCB43D7@SHSMSX101.ccr.corp.intel.com> (Chuanxiao Dong's message of "Sun, 8 Jan 2012 02:18:44 +0000") Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: "Dong, Chuanxiao" Cc: "S, Venkatraman" , Jaehoon Chung , linux-mmc , Kyungmin Park , Hanumath Prasad , "per.forlin@stericsson.com" , Sebastian Rasmussen , Konstantin Dorfman Hi, On Sat, Jan 07 2012, Dong, Chuanxiao wrote: >> In my understanding, the EXT_CSD_BKOPS_EN should be _updated_by_ the >> host controller to 1 at initialization time, to indicate to the >> device, as per the spec. >> Otherwise, the device would decide that the host doesn't support >> software controlled BKOPS. > > EXT_CSD_BKOPS_EN is a onetime programmable register, which is not > suitable for driver to touch I think. This can be updated by host > controller, but should not happened in driver. This register can be > configured by some platform firmware or some eMMC FW from vendor. For > what driver needs to do, is just to read this onetime programmable and > to know whether BKOPS is enabled. It is like hardware reset > feature. RST_n_FUNCTION is only a onetime programmable register which > can indicate whether hardware reset feature is enabled. Driver just > needs to read it out and to know whether hardware reset feature can be > used. So I agree with Jaehoon Chung's implementation. I agree -- we don't touch fuses in the driver. Thanks, - Chris. -- Chris Ball One Laptop Per Child