On Fri, Nov 04, 2022 at 08:24:14AM -0700, Lizhi Hou wrote:
> The PCIe endpoint device such as Xilinx Alveo PCIe card maps the register
> spaces from multiple hardware peripherals to its PCIe BAR. Normally,
> the PCI core discovers devices and BARs using the PCI enumeration process.
> There is no infrastructure to discover the hardware peripherals that are
> present in a PCI device, and which can be accessed through the PCI BARs.
>
> For Alveo PCIe card, the card firmware provides a flattened device tree to
> describe the hardware peripherals on its BARs. The Alveo card driver can
> load this flattened device tree and leverage device tree framework to
> generate platform devices for the hardware peripherals eventually.
>
> Apparently, the device tree framework requires a device tree node for the
> PCIe device. Thus, it can generate the device tree nodes for hardware
> peripherals underneath. Because PCIe is self discoverable bus, there might
> not be a device tree node created for PCIe devices. This patch is to add
> support to generate device tree node for PCIe devices. It introduces a
> kernel option. When the option is turned on, the kernel will generate
Specify the kernel option here. These last two sentences should
probably be a separate paragraph because they say specifically what
this patch does.
> device tree nodes for PCI bridges unconditionally.
> It will also generate
> a device tree node for Xilinx Alveo U50 by using PCI quirks.
I think I would split the Xilinx Alveo U50 quirk to a separate patch
from the infrastructure and make this patch more generic.
> +config PCI_DYNAMIC_OF_NODES
> + bool "Device tree node for PCI devices"
> + depends on OF
> + select OF_DYNAMIC
> + help
> + This option enables support for generating device tree nodes for some
> + PCI devices. Thus, the driver of this kind can load and overlay
> + flattened device tree for its downstream devices.
> +
> + Once this option is selected, the device tree nodes will be generated
> + for all PCI/PCIE bridges.
PCI/PCIe
Actually, in this context (and in the commit log), you should just say
"PCI" because there's nothing PCIe-specific here.
> +void of_pci_make_dev_node(struct pci_dev *pdev)
> +{
> + struct device_node *parent, *dt_node = NULL;
> + const char *pci_type = "dev";
> + struct of_changeset *cset;
> + const char *full_name;
> + int ret;
> +
> + /*
> + * if there is already a device tree node linked to this device,
> + * return immediately.
s/if there/If there/
> + */
> + if (pci_device_to_OF_node(pdev))
> + return;
> +
> + /* check if there is device tree node for parent device */
s/check/Check/
Follow the style of the file, which is "capitalize English sentences."
