On Wed, Jun 18, 2025 at 02:50:04PM -0500, Timothy Pearson wrote: > ----- Original Message ----- > > From: "Bjorn Helgaas" <helg...@kernel.org> > > To: "Timothy Pearson" <tpear...@raptorengineering.com> > > Cc: "linuxppc-dev" <linuxppc-dev@lists.ozlabs.org>, "linux-kernel" > > <linux-ker...@vger.kernel.org>, "linux-pci" > > <linux-...@vger.kernel.org>, "Madhavan Srinivasan" <ma...@linux.ibm.com>, > > "Michael Ellerman" <m...@ellerman.id.au>, > > "christophe leroy" <christophe.le...@csgroup.eu>, "Naveen N Rao" > > <nav...@kernel.org>, "Bjorn Helgaas" > > <bhelg...@google.com>, "Shawn Anastasio" > > <sanasta...@raptorengineering.com>, "Lukas Wunner" <lu...@wunner.de> > > Sent: Wednesday, June 18, 2025 2:44:00 PM > > Subject: Re: [PATCH v2 2/6] pci/hotplug/pnv_php: Work around switches with > > broken > > > [+cc Lukas, pciehp expert] > > > > On Wed, Jun 18, 2025 at 11:56:54AM -0500, Timothy Pearson wrote: > >> presence detection > > > > (subject/commit wrapping seems to be on all of these patches) > > > >> The Microsemi Switchtec PM8533 PFX 48xG3 [11f8:8533] PCIe switch system > >> was observed to incorrectly assert the Presence Detect Set bit in its > >> capabilities when tested on a Raptor Computing Systems Blackbird system, > >> resulting in the hot insert path never attempting a rescan of the bus > >> and any downstream devices not being re-detected. > > > > Seems like this switch supports standard PCIe hotplug? Quite a bit of > > this driver looks similar to things in pciehp. Is there some reason > > we can't use pciehp directly? Maybe pciehp could work if there were > > hooks for the PPC-specific bits? > > While that is a good long term goal that Raptor is willing to work > toward, it is non-trivial and will require buy-in from other > stakeholders (e.g. IBM). If practical, I'd like to get this series > merged first, to fix the broken hotplug on our hardware that is > deployed worldwide, then in parallel see what can be done to merge > PowerNV support into pciehp. Would that work?
Yeah, it wouldn't make sense to switch horses at this stage. I guess I was triggered by this patch, which seems to be a workaround for a defect in a device that is probably also used on non-PPC systems, and pciehp would need a similar workaround. But I guess you go on to say that pciehp already does something similar, so it guess it's already covered. Bjorn
