linux-kernel - Re: [PATCH v9 2/2] PCI: xilinx-cpm: Add Versal CPM Root Port driver

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Date:   Wed, 5 Aug 2020 15:43:58 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Bharat Kumar Gogada <bharat.kumar.gogada@...inx.com>
Cc:     linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        bhelgaas@...gle.com, lorenzo.pieralisi@....com, robh@...nel.org,
        maz@...nel.org
Subject: Re: [PATCH v9 2/2] PCI: xilinx-cpm: Add Versal CPM Root Port driver

On Tue, Jun 16, 2020 at 06:26:54PM +0530, Bharat Kumar Gogada wrote:
> - Add support for Versal CPM as Root Port.
> - The Versal ACAP devices include CCIX-PCIe Module (CPM). The integrated
>   block for CPM along with the integrated bridge can function
>   as PCIe Root Port.
> - Bridge error and legacy interrupts in Versal CPM are handled using
>   Versal CPM specific interrupt line.

> +static void xilinx_cpm_pcie_init_port(struct xilinx_cpm_pcie_port *port)
> +{
> +	if (cpm_pcie_link_up(port))
> +		dev_info(port->dev, "PCIe Link is UP\n");
> +	else
> +		dev_info(port->dev, "PCIe Link is DOWN\n");
> +
> +	/* Disable all interrupts */
> +	pcie_write(port, ~XILINX_CPM_PCIE_IDR_ALL_MASK,
> +		   XILINX_CPM_PCIE_REG_IMR);
> +
> +	/* Clear pending interrupts */
> +	pcie_write(port, pcie_read(port, XILINX_CPM_PCIE_REG_IDR) &
> +		   XILINX_CPM_PCIE_IMR_ALL_MASK,
> +		   XILINX_CPM_PCIE_REG_IDR);
> +
> +	/*
> +	 * XILINX_CPM_PCIE_MISC_IR_ENABLE register is mapped to
> +	 * CPM SLCR block.
> +	 */
> +	writel(XILINX_CPM_PCIE_MISC_IR_LOCAL,
> +	       port->cpm_base + XILINX_CPM_PCIE_MISC_IR_ENABLE);
> +	/* Enable the Bridge enable bit */
> +	pcie_write(port, pcie_read(port, XILINX_CPM_PCIE_REG_RPSC) |
> +		   XILINX_CPM_PCIE_REG_RPSC_BEN,
> +		   XILINX_CPM_PCIE_REG_RPSC);
> +}
> +
> +/**
> + * xilinx_cpm_pcie_parse_dt - Parse Device tree
> + * @port: PCIe port information
> + * @bus_range: Bus resource
> + *
> + * Return: '0' on success and error value on failure
> + */
> +static int xilinx_cpm_pcie_parse_dt(struct xilinx_cpm_pcie_port *port,
> +				    struct resource *bus_range)
> +{
> +	struct device *dev = port->dev;
> +	struct platform_device *pdev = to_platform_device(dev);
> +	struct resource *res;
> +
> +	port->cpm_base = devm_platform_ioremap_resource_byname(pdev,
> +							       "cpm_slcr");
> +	if (IS_ERR(port->cpm_base))
> +		return PTR_ERR(port->cpm_base);
> +
> +	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "cfg");
> +	if (!res)
> +		return -ENXIO;
> +
> +	port->cfg = pci_ecam_create(dev, res, bus_range,
> +				    &pci_generic_ecam_ops);

Aren't we passing an uninitialized pointer (bus_range) here?  This
looks broken to me.

The kernelci build warns about it:
https://kernelci.org/build/next/branch/master/kernel/next-20200805/

  /scratch/linux/drivers/pci/controller/pcie-xilinx-cpm.c:557:39: warning: variable 'bus_range' is uninitialized when used here [-Wuninitialized]

I'm dropping this for now.  I can't believe this actually works.

Bjorn