From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id F0103CAC5B1 for ; Thu, 25 Sep 2025 14:54:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:References: List-Owner; bh=bLz+eCfPxQRSJq/FYoup19CDiPxNuQfA57VJY+B5wAA=; b=2+Lk75fPBNIUvE MMfQXLou8nsXobyoEiazLIoib3XqTEYOd2f33B9Hkggpm3DtiwUvZWBLmwGsL/TLyAldUsCmhtGZf 7yvFY2GhBaYGT/R7U2FFuInvc78Owkbx31OkirklPQrp3zBjmISRiaim/CIRykSIc60UOyFG1ED6x pWJ3QOGaj/8tqHA/X47XSqFWGmbu3epw1AsUZrWF7yQfCl/K5qzAyoxWc5tgyjTNl0ZDZmrUaLjVt Y/bahjAfLG/8ATE+KITOu8WqIDPadFz0MWKtp94GmUVSdY3TfbkFVpB/dMgQGLlfLkiqAqArf67+b qhsGP/qRdWjSbUx6s5dA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1v1nMT-0000000AIni-1UIP; Thu, 25 Sep 2025 14:54:21 +0000 Received: from tor.source.kernel.org ([172.105.4.254]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1v1nMR-0000000AIm7-3htk for linux-arm-kernel@lists.infradead.org; Thu, 25 Sep 2025 14:54:19 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id 512B86060B; Thu, 25 Sep 2025 14:54:19 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B1156C4CEF5; Thu, 25 Sep 2025 14:54:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1758812059; bh=jPB4xVjcQGBdG5oVew+Lht5SAent64Z1rar77L6+Oek=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=u0ikscfs6G31P4bXOTz2TswSzOQR1fdgspn6lZ9NqdIHjbRuPl15mbV861jRpCSKh ONvJHPSdZM0VQeYD6iNJ22uILG6QNWyf/AloAuCz3WEFLN8B5MfTy2fDdP7lJsYS7P vLG4AbgEUPbVVSPUSzdqXrNxu6uMJ6IdN417gD/aevH9gFc1x74tpQuA5LplmbtVfE eD11RHPJKmcJYA71znv9g5U8UfhkdBzU1qOzhnEad5xxWHVkHj8XJYB5pL9rDGZMC8 M3QXZyRYhzwSrWnHvXoyvj2oWYw4hsJefjMtK4o65vqycS5pl0o9GTT4tVhEYYb9C0 28VOTxnZsP7Pg== Date: Thu, 25 Sep 2025 09:54:16 -0500 From: Bjorn Helgaas To: Krishna Chaitanya Chundru Cc: Bjorn Helgaas , Lorenzo Pieralisi , Rob Herring , Krzysztof Kozlowski , Conor Dooley , chaitanya chundru , Bjorn Andersson , Konrad Dybcio , cros-qcom-dts-watchers@chromium.org, Jingoo Han , Bartosz Golaszewski , Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= , Manivannan Sadhasivam , Catalin Marinas , Will Deacon , quic_vbadigan@quicnic.com, amitk@kernel.org, linux-pci@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, jorge.ramirez@oss.qualcomm.com, linux-arm-kernel@lists.infradead.org, Dmitry Baryshkov Subject: Re: [PATCH v6 5/9] PCI: dwc: Implement .start_link(), .stop_link() hooks Message-ID: <20250925145416.GA2164008@bhelgaas> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250828-qps615_v4_1-v6-5-985f90a7dd03@oss.qualcomm.com> X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Aug 28, 2025 at 05:39:02PM +0530, Krishna Chaitanya Chundru wrote: > Implement stop_link() and start_link() function op for dwc drivers. > > Signed-off-by: Krishna Chaitanya Chundru > --- > drivers/pci/controller/dwc/pcie-designware-host.c | 18 ++++++++++++++++++ > 1 file changed, 18 insertions(+) > > diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c > index 952f8594b501254d2b2de5d5e056e16d2aa8d4b7..bcdc4a0e4b4747f2d62e1b67bc1aeda16e35acdd 100644 > --- a/drivers/pci/controller/dwc/pcie-designware-host.c > +++ b/drivers/pci/controller/dwc/pcie-designware-host.c > @@ -722,10 +722,28 @@ void __iomem *dw_pcie_own_conf_map_bus(struct pci_bus *bus, unsigned int devfn, > } > EXPORT_SYMBOL_GPL(dw_pcie_own_conf_map_bus); > > +static int dw_pcie_op_start_link(struct pci_bus *bus) > +{ > + struct dw_pcie_rp *pp = bus->sysdata; > + struct dw_pcie *pci = to_dw_pcie_from_pp(pp); > + > + return dw_pcie_host_start_link(pci); This takes a pci_bus *, which could be any PCI bus, but this only works for root buses because it affects the link from a Root Port. I know the TC9563 is directly below the Root Port in the current topology, but it seems like the ability to configure a Switch with I2C or similar is potentially of general interest, even if the switch is deeper in the hierarchy. Is there a generic way to inhibit link training, e.g., with the Link Disable bit in the Link Control register? If so, this could potentially be done in a way that would work for any vendor and for any Downstream Port, including Root Ports and Switch Downstream Ports. > +} > + > +static void dw_pcie_op_stop_link(struct pci_bus *bus) > +{ > + struct dw_pcie_rp *pp = bus->sysdata; > + struct dw_pcie *pci = to_dw_pcie_from_pp(pp); > + > + dw_pcie_host_stop_link(pci); > +} > + > static struct pci_ops dw_pcie_ops = { > .map_bus = dw_pcie_own_conf_map_bus, > .read = pci_generic_config_read, > .write = pci_generic_config_write, > + .start_link = dw_pcie_op_start_link, > + .stop_link = dw_pcie_op_stop_link, > }; > > static int dw_pcie_iatu_setup(struct dw_pcie_rp *pp) > > -- > 2.34.1 >