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Wed, 13 Nov 2024 09:15:23 -0800 (PST) Received: from thinkpad ([117.213.102.160]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-21177dc8f25sm112819815ad.22.2024.11.13.09.15.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 13 Nov 2024 09:15:22 -0800 (PST) Date: Wed, 13 Nov 2024 22:45:11 +0530 From: Manivannan Sadhasivam To: Frank Li Cc: Bjorn Helgaas , Richard Zhu , Lucas Stach , Lorenzo Pieralisi , Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= , Rob Herring , Shawn Guo , Sascha Hauer , Pengutronix Kernel Team , Fabio Estevam , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, imx@lists.linux.dev, alyssa@rosenzweig.io, bpf@vger.kernel.org, broonie@kernel.org, jgg@ziepe.ca, joro@8bytes.org, lgirdwood@gmail.com, maz@kernel.org, p.zabel@pengutronix.de, robin.murphy@arm.com, will@kernel.org Subject: Re: [PATCH v5 1/2] PCI: Add enable_device() and disable_device() callbacks for bridges Message-ID: <20241113171511.6d4gh3x27nej55qw@thinkpad> References: <20241104-imx95_lut-v5-0-feb972f3f13b@nxp.com> <20241104-imx95_lut-v5-1-feb972f3f13b@nxp.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20241104-imx95_lut-v5-1-feb972f3f13b@nxp.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20241113_091525_433479_56B2FE55 X-CRM114-Status: GOOD ( 32.53 ) 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 Mon, Nov 04, 2024 at 02:22:59PM -0500, Frank Li wrote: > Some PCIe host bridges require special handling when enabling or disabling > PCIe Endpoints. For example, the i.MX95 platform has a lookup table to map > Requester IDs to StreamIDs, which are used by the SMMU and MSI controller > to identify the source of DMA accesses. > > Without this mapping, DMA accesses may target unintended memory, which > would corrupt memory or read the wrong data. > > Add a host bridge .enable_device() hook the imx6 driver can use to > configure the Requester ID to StreamID mapping. The hardware table isn't > big enough to map all possible Requester IDs, so this hook may fail if no > table space is available. In that case, return failure from > pci_enable_device(). > > It might make more sense to make pci_set_master() decline to enable bus > mastering and return failure, but it currently doesn't have a way to return > failure. > > Signed-off-by: Frank Li Acked-by: Manivannan Sadhasivam - Mani > --- > Change from v4 to v5 > - Add two static help functions > int pci_host_bridge_enable_device(dev); > void pci_host_bridge_disable_device(dev); > - remove tags because big change > Acked-by: Bjorn Helgaas > Reviewed-by: Marc Zyngier > Tested-by: Marc Zyngier > > Change from v3 to v4 > - Add Bjorn's ack tag > > Change from v2 to v3 > - use Bjorn suggest's commit message. > - call disable_device() when error happen. > > Change from v1 to v2 > - move enable(disable)device ops to pci_host_bridge > --- > drivers/pci/pci.c | 36 +++++++++++++++++++++++++++++++++++- > include/linux/pci.h | 2 ++ > 2 files changed, 37 insertions(+), 1 deletion(-) > > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c > index 67013df89a694..4735bc665ab3b 100644 > --- a/drivers/pci/pci.c > +++ b/drivers/pci/pci.c > @@ -2055,6 +2055,28 @@ int __weak pcibios_enable_device(struct pci_dev *dev, int bars) > return pci_enable_resources(dev, bars); > } > > +static int pci_host_bridge_enable_device(struct pci_dev *dev) > +{ > + struct pci_host_bridge *host_bridge = pci_find_host_bridge(dev->bus); > + int err; > + > + if (host_bridge && host_bridge->enable_device) { > + err = host_bridge->enable_device(host_bridge, dev); > + if (err) > + return err; > + } > + > + return 0; > +} > + > +static void pci_host_bridge_disable_device(struct pci_dev *dev) > +{ > + struct pci_host_bridge *host_bridge = pci_find_host_bridge(dev->bus); > + > + if (host_bridge && host_bridge->disable_device) > + host_bridge->disable_device(host_bridge, dev); > +} > + > static int do_pci_enable_device(struct pci_dev *dev, int bars) > { > int err; > @@ -2070,9 +2092,13 @@ static int do_pci_enable_device(struct pci_dev *dev, int bars) > if (bridge) > pcie_aspm_powersave_config_link(bridge); > > + err = pci_host_bridge_enable_device(dev); > + if (err) > + return err; > + > err = pcibios_enable_device(dev, bars); > if (err < 0) > - return err; > + goto err_enable; > pci_fixup_device(pci_fixup_enable, dev); > > if (dev->msi_enabled || dev->msix_enabled) > @@ -2087,6 +2113,12 @@ static int do_pci_enable_device(struct pci_dev *dev, int bars) > } > > return 0; > + > +err_enable: > + pci_host_bridge_disable_device(dev); > + > + return err; > + > } > > /** > @@ -2270,6 +2302,8 @@ void pci_disable_device(struct pci_dev *dev) > if (atomic_dec_return(&dev->enable_cnt) != 0) > return; > > + pci_host_bridge_disable_device(dev); > + > do_pci_disable_device(dev); > > dev->is_busmaster = 0; > diff --git a/include/linux/pci.h b/include/linux/pci.h > index a17edc6c28fda..5f75c30f263be 100644 > --- a/include/linux/pci.h > +++ b/include/linux/pci.h > @@ -596,6 +596,8 @@ struct pci_host_bridge { > u8 (*swizzle_irq)(struct pci_dev *, u8 *); /* Platform IRQ swizzler */ > int (*map_irq)(const struct pci_dev *, u8, u8); > void (*release_fn)(struct pci_host_bridge *); > + int (*enable_device)(struct pci_host_bridge *bridge, struct pci_dev *dev); > + void (*disable_device)(struct pci_host_bridge *bridge, struct pci_dev *dev); > void *release_data; > unsigned int ignore_reset_delay:1; /* For entire hierarchy */ > unsigned int no_ext_tags:1; /* No Extended Tags */ > > -- > 2.34.1 > -- மணிவண்ணன் சதாசிவம்