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Message-ID:
<VI0PR04MB121147530D601C77D1977269A9298A@VI0PR04MB12114.eurprd04.prod.outlook.com>
Date: Wed, 4 Feb 2026 06:33:04 +0000
From: Sherry Sun <sherry.sun@....com>
To: Manivannan Sadhasivam <mani@...nel.org>
CC: Hongxing Zhu <hongxing.zhu@....com>, "l.stach@...gutronix.de"
<l.stach@...gutronix.de>, Frank Li <frank.li@....com>, "bhelgaas@...gle.com"
<bhelgaas@...gle.com>, "lpieralisi@...nel.org" <lpieralisi@...nel.org>,
"kwilczynski@...nel.org" <kwilczynski@...nel.org>, "robh@...nel.org"
<robh@...nel.org>, "krzk+dt@...nel.org" <krzk+dt@...nel.org>,
"conor+dt@...nel.org" <conor+dt@...nel.org>, "s.hauer@...gutronix.de"
<s.hauer@...gutronix.de>, "festevam@...il.com" <festevam@...il.com>,
"imx@...ts.linux.dev" <imx@...ts.linux.dev>, "kernel@...gutronix.de"
<kernel@...gutronix.de>, "linux-pci@...r.kernel.org"
<linux-pci@...r.kernel.org>, "linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>, "devicetree@...r.kernel.org"
<devicetree@...r.kernel.org>, "linux-kernel@...r.kernel.org"
<linux-kernel@...r.kernel.org>
Subject: RE: [PATCH V3 02/10] PCI: imx6: Add support for parsing the reset
property in new Root Port binding
> On Tue, Feb 03, 2026 at 09:56:06AM +0800, Sherry Sun wrote:
> > DT binding allows specifying 'reset' property in both host bridge and
> > Root Port nodes, but specifying in the host bridge node is marked as
> > deprecated. So add support for parsing the new binding that uses
> > 'reset-gpios' property for PERST#.
> >
> > The initial idea is to add the PCIe M.2 KeyE connector support and PCI
> > power control framework to the pcie-imx6 driver. Since the new
> > M.2/pwrctrl model is implemented based on Root Ports and requires the
> > pwrctrl driver to bind to a Root Port device, we need to introduce a
> > Root Port child node on i.MX boards that provide an M.2 connector.
> >
> > To follow a more standardized DT structure, it also makes sense to
> > move the reset-gpios and wake-gpios properties into the Root Port
> > node. These signals logically belong to the Root Port rather than the
> > host bridge, and placing them there aligns with the new M.2/pwrctrl model.
> >
> > To maintain DT backwards compatibility, fallback to the legacy method
> > of parsing the host bridge node if the reset property is not present
> > in the Root Port node.
> >
> > Signed-off-by: Sherry Sun <sherry.sun@....com>
> > ---
> > drivers/pci/controller/dwc/pci-imx6.c | 123
> > +++++++++++++++++++++++---
> > 1 file changed, 109 insertions(+), 14 deletions(-)
> >
> > diff --git a/drivers/pci/controller/dwc/pci-imx6.c
> > b/drivers/pci/controller/dwc/pci-imx6.c
> > index a5b8d0b71677..e3ba68976bee 100644
> > --- a/drivers/pci/controller/dwc/pci-imx6.c
> > +++ b/drivers/pci/controller/dwc/pci-imx6.c
> > @@ -148,10 +148,15 @@ struct imx_lut_data {
> > u32 data2;
> > };
> >
> > +struct imx_pcie_port {
> > + struct list_head list;
> > + struct gpio_desc *reset;
> > +};
> > +
>
> I'd love to abstract the Root Port properties in a generic struct so that we can
> introduce generic APIs to parse the ports. But I'm not asking you to
> implement it :)
>
> > struct imx_pcie {
> > struct dw_pcie *pci;
> > - struct gpio_desc *reset_gpiod;
> > struct clk_bulk_data *clks;
> > + struct list_head ports;
> > int num_clks;
> > bool supports_clkreq;
> > bool enable_ext_refclk;
> > @@ -897,29 +902,35 @@ static int imx95_pcie_core_reset(struct imx_pcie
> > *imx_pcie, bool assert)
> >
> > static void imx_pcie_assert_core_reset(struct imx_pcie *imx_pcie) {
> > + struct imx_pcie_port *port;
> > +
> > reset_control_assert(imx_pcie->pciephy_reset);
> >
> > if (imx_pcie->drvdata->core_reset)
> > imx_pcie->drvdata->core_reset(imx_pcie, true);
> >
> > /* Some boards don't have PCIe reset GPIO. */
> > - gpiod_set_value_cansleep(imx_pcie->reset_gpiod, 1);
> > + list_for_each_entry(port, &imx_pcie->ports, list)
> > + gpiod_set_value_cansleep(port->reset, 1);
> > }
> >
> > static int imx_pcie_deassert_core_reset(struct imx_pcie *imx_pcie) {
> > + struct imx_pcie_port *port;
> > +
> > reset_control_deassert(imx_pcie->pciephy_reset);
> >
> > if (imx_pcie->drvdata->core_reset)
> > imx_pcie->drvdata->core_reset(imx_pcie, false);
> >
> > /* Some boards don't have PCIe reset GPIO. */
> > - if (imx_pcie->reset_gpiod) {
> > - msleep(100);
> > - gpiod_set_value_cansleep(imx_pcie->reset_gpiod, 0);
> > - /* Wait for 100ms after PERST# deassertion (PCIe r5.0, 6.6.1)
> */
> > - msleep(100);
> > - }
> > + list_for_each_entry(port, &imx_pcie->ports, list)
> > + if (port->reset) {
> > + msleep(100);
>
> PCIE_T_PERST_CLK_US
>
> > + gpiod_set_value_cansleep(port->reset, 0);
> > + /* Wait for 100ms after PERST# deassertion (PCIe
> r5.0, 6.6.1) */
> > + msleep(100);
>
> Remove the comment and just use PCIE_T_PVPERL_MS.
Ack, I will use PCIE_T_PVPERL_MS and PCIE_RESET_CONFIG_WAIT_MS here.
>
> > + }
> >
> > return 0;
> > }
> > @@ -1642,6 +1653,76 @@ static const struct dev_pm_ops
> imx_pcie_pm_ops = {
> > imx_pcie_resume_noirq)
> > };
> >
> > +static void imx_pcie_delete_ports(void *data) {
> > + struct imx_pcie *pcie = data;
> > + struct imx_pcie_port *port, *tmp;
> > +
> > + list_for_each_entry_safe(port, tmp, &pcie->ports, list)
> > + list_del(&port->list);
> > +}
> > +
> > +static int imx_pcie_parse_port(struct imx_pcie *pcie, struct
> > +device_node *node) {
> > + struct device *dev = pcie->pci->dev;
> > + struct imx_pcie_port *port;
> > + struct gpio_desc *reset;
> > +
> > + reset = devm_fwnode_gpiod_get(dev, of_fwnode_handle(node),
> > + "reset", GPIOD_OUT_HIGH, "PCIe reset");
>
> s/"PCIe reset"/"PERST#"
Ok, will do.
>
> > + if (IS_ERR(reset))
> > + return PTR_ERR(reset);
> > +
> > + port = devm_kzalloc(dev, sizeof(*port), GFP_KERNEL);
> > + if (!port)
> > + return -ENOMEM;
> > +
> > + port->reset = reset;
> > + INIT_LIST_HEAD(&port->list);
> > + list_add_tail(&port->list, &pcie->ports);
> > +
> > + return 0;
> > +}
> > +
> > +static int imx_pcie_parse_ports(struct imx_pcie *pcie) {
> > + struct device *dev = pcie->pci->dev;
> > + int ret = -ENOENT;
> > +
> > + for_each_available_child_of_node_scoped(dev->of_node, of_port) {
> > + if (!of_node_is_type(of_port, "pci"))
> > + continue;
> > + ret = imx_pcie_parse_port(pcie, of_port);
> > + if (ret) {
> > + imx_pcie_delete_ports(pcie);
> > + return ret;
> > + }
> > + }
> > +
> > + return ret;
> > +}
> > +
> > +static int imx_pcie_parse_legacy_binding(struct imx_pcie *pcie) {
> > + struct device *dev = pcie->pci->dev;
> > + struct imx_pcie_port *port;
> > + struct gpio_desc *reset;
> > +
> > + reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
> > + if (IS_ERR(reset))
> > + return PTR_ERR(reset);
> > +
> > + port = devm_kzalloc(dev, sizeof(*port), GFP_KERNEL);
> > + if (!port)
> > + return -ENOMEM;
> > +
> > + port->reset = reset;
> > + INIT_LIST_HEAD(&port->list);
> > + list_add_tail(&port->list, &pcie->ports);
> > +
> > + return 0;
> > +}
> > +
> > static int imx_pcie_probe(struct platform_device *pdev) {
> > struct device *dev = &pdev->dev;
> > @@ -1660,6 +1741,8 @@ static int imx_pcie_probe(struct platform_device
> *pdev)
> > if (!pci)
> > return -ENOMEM;
> >
> > + INIT_LIST_HEAD(&imx_pcie->ports);
> > +
> > pci->dev = dev;
> > pci->ops = &dw_pcie_ops;
> >
> > @@ -1688,12 +1771,24 @@ static int imx_pcie_probe(struct
> platform_device *pdev)
> > return PTR_ERR(imx_pcie->phy_base);
> > }
> >
> > - /* Fetch GPIOs */
> > - imx_pcie->reset_gpiod = devm_gpiod_get_optional(dev, "reset",
> GPIOD_OUT_HIGH);
> > - if (IS_ERR(imx_pcie->reset_gpiod))
> > - return dev_err_probe(dev, PTR_ERR(imx_pcie->reset_gpiod),
> > - "unable to get reset gpio\n");
> > - gpiod_set_consumer_name(imx_pcie->reset_gpiod, "PCIe reset");
> > + ret = imx_pcie_parse_ports(imx_pcie);
> > + if (ret) {
> > + if (ret != -ENOENT)
> > + return dev_err_probe(dev, ret, "Failed to parse Root
> Port: %d\n",
> > +ret);
> > +
> > + /*
> > + * In the case of properties not populated in Root Port node,
> > + * fallback to the legacy method of parsing the Host Bridge
> > + * node. This is to maintain DT backwards compatibility.
> > + */
> > + ret = imx_pcie_parse_legacy_binding(imx_pcie);
> > + if (ret)
> > + return dev_err_probe(dev, ret, "Unable to get reset
> gpio: %d\n", ret);
> > + }
> > +
> > + ret = devm_add_action_or_reset(dev, imx_pcie_delete_ports,
> imx_pcie);
> > + if (ret)
> > + return ret;
>
> I'd prefer to do it in err labels.
As Frank commented, imx_pcie_probe() currently doesn’t have err label, we'd like keep this way.
Best Regards
Sherry
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