From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTP id 57B4ADDE21 for ; Tue, 7 Aug 2007 04:04:31 +1000 (EST) In-Reply-To: <20070801165140.3e176cd1@the-village.bc.nu> References: <20061130165202.GA23205@aepfle.de> <20061204123854.GA28159@aepfle.de> <4574197A.2020204@ru.mvista.com> <4FC2EBCF-C927-435A-9BE3-E4403AFC042D@kernel.crashing.org> <45741DDE.4080509@ru.mvista.com> <20061204132124.4f7c50a9@localhost.localdomain> <52F5B831-5B40-4D40-A77F-4D7484692CAE@kernel.crashing.org> <46B0972C.3020000@ru.mvista.com> <20070801165140.3e176cd1@the-village.bc.nu> Mime-Version: 1.0 (Apple Message framework v623) Content-Type: text/plain; charset=US-ASCII; format=flowed Message-Id: <04ce93c63dfaa543b4068d448c8115d8@kernel.crashing.org> From: Segher Boessenkool Subject: Re: [PATCH] mark PCI resource with start 0 as unassigned Date: Mon, 6 Aug 2007 20:04:17 +0200 To: Alan Cox Cc: linuxppc-dev@ozlabs.org, Olaf Hering , linux-ide@vger.kernel.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , >>> But 0 _is_ a valid PCI I/O address. Do we now have to start >> >> I wasn't in PCI 2.1 (later the corresponding passage have >> disppeared). > > SFF controllers often use 0 to indicate a channel isn't configured and > present. Libata and old IDE both assume these semantics for an SFF > IDE device reporting address zero. It matches the hardware behaviour. > > I would suggest you don't map one at I/O zero on your PCI. That's of course the smarter choice, _if_ we have a choice at all -- on PowerPC, the PCI setup on certain platforms is done by the firmware (and we don't want to mess with it for various reasons), and some _do_ map PCI legacy I/O at 0. Not in this case though, so let's just ignore that possibility until it hits us in the face :-) Segher