From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Garzik Subject: Re: [PATCH 11/14] libata-hp-prep: make ops->tf_read() optional Date: Fri, 19 May 2006 11:11:48 -0400 Message-ID: <446DE034.6030103@pobox.com> References: <11480445844029-git-send-email-htejun@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from srv5.dvmed.net ([207.36.208.214]:48806 "EHLO mail.dvmed.net") by vger.kernel.org with ESMTP id S932329AbWESPME (ORCPT ); Fri, 19 May 2006 11:12:04 -0400 In-Reply-To: <11480445844029-git-send-email-htejun@gmail.com> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Tejun Heo Cc: mlord@pobox.com, albertcc@tw.ibm.com, alan@lxorguk.ukuu.org.uk, axboe@suse.de, forrest.zhao@intel.com, linux-ide@vger.kernel.org Tejun Heo wrote: > Not all controllers have single TF image and ops->tf_read() is > inappropriate for them. Newly implemented hotplug probing will allow > drivers for such controllers to get rid of ops->tf_read() completely. > Make ops->tf_read() optional in core layer. > > Signed-off-by: Tejun Heo NAK. At the present time, the controller model expects to be able to obtain correct values from the shadow registers. For FIS-based controllers, this may imply that the driver needs to maintain an accurate shadow register image, if the chip doesn't automatically supply one. I think this is a quite reasonable expectation, given that ATA continues to have specifically defined shadow register outputs, and even in the face of NCQ, we have defined states where the shadow registers are available. On this basis, attempts to make ->check_status() optional are also NAK'd. Jeff