From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0DEA33085BA; Wed, 18 Jun 2025 20:17:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750277845; cv=none; b=bKKJQLlLArXv1M7K8sMryueZ5pIr1H9LzMFLSUuKyi2HVYfsam3KK3a14bhYXq+Xek86yYFqhiDmsic6ScOdWYm2yKiYlqaD0PnoQoFJJ9u/7qFtONZOYqBNi9KBMbKL+rqpeZCkYM6PxxzyAHTcPjtrRBX4di4uyQaHPMq0jZY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750277845; c=relaxed/simple; bh=xt8r64iKztaGluvYHQ+nEmHkrlN0zD8k22lRNBw+eZk=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition:In-Reply-To; b=b03cQu5u08v4Nt2cBCaBvhj2CRDQuH9YKGUy/FT4Ylkv7Ei6rGfeiupMU5scW/3hMLdsgrOsZqCDTZXAJgRZMtsBfS542+FxUYU4j80dpIDRl8giDqep7kh9o4INAf72GscRDsdosnKy+yK/3ocv891Jr/fbgeM0TYvUUbPMa44= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=FOARzafB; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="FOARzafB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5BB27C4CEE7; Wed, 18 Jun 2025 20:17:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1750277844; bh=xt8r64iKztaGluvYHQ+nEmHkrlN0zD8k22lRNBw+eZk=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=FOARzafBQCH4mhbZUSX3MH98F55tLlayT4MS64DrQ26ru2cMm/M+yF+FscGystMAK 0CQma9JT95xIs7U+K1HMp/Z/U9ZfclyD935P5ZdedHfyuuVMdWfGxcjMxVNDL3VZtq kLYIts2/TIO9aXT4ITDKOIVP7tvcnQnttyhvDkyBX0uRIX6cu8hEVbW11K6/nJVLXU TYCHVddc6BvT/c1MJHUMD20a7ia6cvoqPypNfuKOeSqB50zMSq1UHzbSgjEKU5yZEN /uBRVpWVWLcm5YfhOu/Ug21FEc722Jpq7hOGt8MX4XOpYNYWhXfg3DIgM4PzHSPIPD tf7OpPfRTsrcQ== Date: Wed, 18 Jun 2025 15:17:22 -0500 From: Bjorn Helgaas To: Timothy Pearson Cc: linuxppc-dev , linux-kernel , linux-pci , Madhavan Srinivasan , Michael Ellerman , christophe leroy , Naveen N Rao , Bjorn Helgaas , Shawn Anastasio , Lukas Wunner Subject: Re: [PATCH v2 2/6] pci/hotplug/pnv_php: Work around switches with broken Message-ID: <20250618201722.GA1220739@bhelgaas> Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1957898084.1311382.1750276204022.JavaMail.zimbra@raptorengineeringinc.com> On Wed, Jun 18, 2025 at 02:50:04PM -0500, Timothy Pearson wrote: > ----- Original Message ----- > > From: "Bjorn Helgaas" > > To: "Timothy Pearson" > > Cc: "linuxppc-dev" , "linux-kernel" , "linux-pci" > > , "Madhavan Srinivasan" , "Michael Ellerman" , > > "christophe leroy" , "Naveen N Rao" , "Bjorn Helgaas" > > , "Shawn Anastasio" , "Lukas Wunner" > > 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