From mboxrd@z Thu Jan 1 00:00:00 1970 From: Randy Dunlap Subject: Re: RFC: ACPI/scsi/libata integration and hotswap Date: Tue, 13 Dec 2005 11:07:27 -0800 Message-ID: <20051213110727.2bef7d80.randy_d_dunlap@linux.intel.com> References: <20051208030242.GA19923@srcf.ucam.org> <20051213101417.13fdb14c.randy_d_dunlap@linux.intel.com> <20051213182651.GA14645@srcf.ucam.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20051213182651.GA14645@srcf.ucam.org> Sender: linux-kernel-owner@vger.kernel.org To: Matthew Garrett Cc: linux-ide@vger.kernel.org, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, acpi-devel@lists.sourceforge.net List-Id: linux-ide@vger.kernel.org On Tue, 13 Dec 2005 18:26:51 +0000 Matthew Garrett wrote: > On Tue, Dec 13, 2005 at 10:14:17AM -0800, Randy Dunlap wrote: > > > 7. Most important: What good does the ACPI interface do/add? > > What I mean is that acpi_get_child() in scsi_acpi_find_channel() > > always returns a handle value of 0, so it doesn't get us > > any closer to determining the ACPI address (_ADR) of the SATA > > devices. The acpi_get_devices() technique in my patch (basically > > walking the ACPI namespace, looking at all "devices") is the > > only way that I know of doing this, but I would certainly > > like to find a better way. > > When the PCI bus is registered, acpi walks it and finds the appropriate > acpi handle for each PCI device. This is shoved in the > firmware_data field of the device structure. Later on, we register the > scsi bus. As each item on the bus is added, the acpi callback gets > called. If it's not an endpoint, scsi_acpi_find_channel gets called. > We're worried about the host case. The host number will correspond to > the appropriate _ADR underneath the PCI device that the host is on, so > we simply get the handle of the PCI device and then ask for the child > with the appropriate _ADR. That gives us the handle for the device, and > returning that sticks it back in the child's firmware_data field. > > At least, that's how it works here. If acpi_get_child always returns 0 > for you, then it sounds like something's going horribly wrong. Do you > have a copy of the DSDT? Thanks for the explanation. The 136 KB DSDT is at: http://www.xenotime.net/linux/SATA/acpitbl.out . --- ~Randy