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 A4CD842A85; Fri, 12 Jan 2024 14:33:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="XECdFivI" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 06FDEC433C7; Fri, 12 Jan 2024 14:33:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1705070003; bh=JQFb0RwgqiOgAMfJwRMmXuTQbRDzY81oEPCIHnqCcqU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=XECdFivIpDVFW8d+q1cmUj0ydJ04m25sDXk08JNeJU9TSTa+XzAfMKH3SZIOeywQg 4aqirrDf11dWd0P7Un0TmdFh9UgFGd+se/YhlLdw2i6EFN+ZqbzUUmC8gd+tViFnSs rJOHj8FRnqenuK9S2LGHVpS2Dr2HVNXE3U1Bbt89TSi6aTTuTyL3E283fecMbHdcyS Tm3tGHDglm8Dm+BKGjiEm03m7a+85u/yoB8pUaeKGTnaY9EkBT71dZAZ6lvduX6HqE DdDkCIVOlEd+oU6y/M4YdFspRKI98xxWM4F1t462Y8dTP4oFqXdf6jJU26l16G8ZvZ bvjQMuzu7vevg== Date: Fri, 12 Jan 2024 08:33:20 -0600 From: Rob Herring To: Vidya Sagar Cc: lpieralisi@kernel.org, kw@linux.com, bhelgaas@google.com, krzysztof.kozlowski+dt@linaro.org, conor+dt@kernel.org, will@kernel.org, frowand.list@gmail.com, linux-pci@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, treding@nvidia.com, jonathanh@nvidia.com, kthota@nvidia.com, mmaddireddy@nvidia.com, sagar.tv@gmail.com Subject: Re: [PATCH V2 1/2] dt-bindings: Add PCIe "preserve-boot-config" property Message-ID: <20240112143320.GA3143039-robh@kernel.org> References: <20240110030725.710547-1-vidyas@nvidia.com> <20240110030725.710547-2-vidyas@nvidia.com> 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: <20240110030725.710547-2-vidyas@nvidia.com> On Wed, Jan 10, 2024 at 08:37:24AM +0530, Vidya Sagar wrote: > The existing "linux,pci-probe-only" property applies at a system level > and it is not possible to selectively convey individual host bridge's > requirement w.r.t preserving the boot configuration done by the platform > firmware to the kernel. "preserve-boot-config" addresses that concern > and can be used to preserve the boot configuration for host bridges > selectivey. > > Signed-off-by: Vidya Sagar > --- > V2: > * None > > Documentation/devicetree/bindings/pci/pci.txt | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/Documentation/devicetree/bindings/pci/pci.txt b/Documentation/devicetree/bindings/pci/pci.txt > index 6a8f2874a24d..0a5ff998cbe8 100644 > --- a/Documentation/devicetree/bindings/pci/pci.txt > +++ b/Documentation/devicetree/bindings/pci/pci.txt > @@ -32,6 +32,10 @@ driver implementation may support the following properties: > root port to downstream device and host bridge drivers can do programming > which depends on CLKREQ signal existence. For example, programming root port > not to advertise ASPM L1 Sub-States support if there is no CLKREQ signal. > +- preserve-boot-config: > + If present this property specifies that this host bridge is already > + configured by the platform firmware and the OS doesn't need to reconfigure > + it again. Anything new must be a schema. Don't create something new to workaround the problem. Extend the existing support. For this, make "linux,pci-probe-only" allowed in host bridge nodes. Yeah, there's the issue that this property sets a global flag, but I'd imagine the PCI maintainers would agree that some flags should/could be per bus. Rob