From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rajesh Shah Date: Thu, 04 Nov 2004 22:22:11 +0000 Subject: Re: pci express switch driver Message-Id: <20041104142211.B6685@unix-os.sc.intel.com> List-Id: References: <73943A6B3BEAA1468EE1A4A090129F436DABCD@corpbridge.corp.idt.com> In-Reply-To: <73943A6B3BEAA1468EE1A4A090129F436DABCD@corpbridge.corp.idt.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-hotplug@vger.kernel.org On Wed, Nov 03, 2004 at 05:52:00PM -0800, Sadik, Pallathu wrote: > Dely, Rajesh and Greg, > > Why special care is needed for hot-plugging the upstream port? > As I understand, even if hot-plug signals are provided on the upstream > port of a switch/endpoint, the generated events gets consumed by > the downstream port of the root complex/switch where this card is plugged. > Hence, the mechanism to handle hot-plugging of the upstream port of > a switch should be same as hot-plugging of the downstream port of the root > port. > When you hot-insert the (upstream port of the) 2nd switch, it may already have some devices connected to it (downstream). Also, the switch _may_ contain hot-pluggable slots (that doesn't appear to be the case with your motherboard). Someone needs to collect resource requirements, program non-conflicting values in the end devices and the summed up resource values in the switch. This is not an issue during boot, since the system firmware has done this already. Also, the hot-added switch may contain IO-APICs (as it does in your case). These need to be added too. Current hotplug drivers don't have the code to support this. > > > > shpchp is used to hot-plug PCI or PCI-X devices. Both > > drivers can run on the same system. > > As I mentioned above, we are planning to use two switches. > Do I still need the shpchp in this case? > Your switch contains an SHPC controller, so you do need this driver to hot-plug PCI/PCI-X devices under the switch. However, your motherboard doesn't appear to support this. > The PCIe hotplug protocol specifies that, when a device is > in D1, D2 or D3hot state, the hot-plug controller generates > a wakeup event (PM_PME) instead of an interrupt. Please see Hmm... I thought you said the motherboard does not support hotplug of IO devices (no attention button/indicator...). What are you trying to do here? Put the switch and all devices under it to a low-power state and then initiate a hot-plug operation on an IO device? > Is there a way to figure out whether the motherboard > supports ACPI tables for PCIe hotplug in the above > fashion? Is it possible to see it from the ACPI > tables that I can get using 'acpidump' command? If it is > not supported, is there a way I can add them? Yes, you can dump your ACPI tables, but changing them to support ACPI based hot-plug is non-trivial. Plus, just updating your DSDT may not be enough, hardware support may be needed. Rajesh ------------------------------------------------------- This SF.Net email is sponsored by: Sybase ASE Linux Express Edition - download now for FREE LinuxWorld Reader's Choice Award Winner for best database on Linux. http://ads.osdn.com/?ad_idU88&alloc_id065&op=click _______________________________________________ Linux-hotplug-devel mailing list http://linux-hotplug.sourceforge.net Linux-hotplug-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-hotplug-devel