From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Garzik Subject: Re: [PATCH] sata_uli: ignore SIMPLEX Date: Fri, 19 Jan 2007 23:05:29 -0500 Message-ID: <45B19509.6080606@pobox.com> References: <20070116055551.GN10987@htj.dyndns.org> <45B15F7E.2080807@pobox.com> <45B18F7F.7000900@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]:54995 "EHLO mail.dvmed.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965158AbXATEFf (ORCPT ); Fri, 19 Jan 2007 23:05:35 -0500 In-Reply-To: <45B18F7F.7000900@gmail.com> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Tejun Heo Cc: linux-ide@vger.kernel.org Tejun Heo wrote: > Jeff Garzik wrote: >> Tejun Heo wrote: >>> Some uli controllers have stuck SIMPLEX bit which can't be cleared >>> with ata_pci_clear_simplex(), but the controller is capable of doing >>> DMAs on both channels simultaneously. Ignore it. >>> >>> Signed-off-by: Tejun Heo >> This is going to be the common case going forward. Please create an >> 'ignore simplex bit' flag, and set it in sata_uli > > I'm a little bit hesitant to do that. > > 1. I don't think we're gonna have a lot of drivers which need this. > Just a few. We've just found one now. > > 2. I think libata core layer (sff included) is burdened with too much > already. Also, now that devres is acked, we can easily transition to > alloc - init - register model which gives LLDs much more flexibility and > this kind of stuff can easily be done in init_one()'s. It just fits there. We need to correct a false assumption in the core. The PCI IDE spec specifies the simplex bit, but a /vast majority/ of controllers, PATA as well as SATA, hardwire the bit, or program it to a value set by BIOS. As such, most drivers really should /just know/ that their hardware need never worry about this odd simplex concept. Jeff