Re: [PATCH v5 3/4] usb: host: xhci-plat: Create platform device for onboard hubs in probe()

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Wed, Feb 10, 2021 at 09:10:38AM -0800, Matthias Kaehlcke wrote:
> Check during probe() if a hub supported by the onboard_usb_hub
> driver is connected to the controller. If such a hub is found
> create the corresponding platform device. This requires the
> device tree to have a node for the hub with its vendor and
> product id (which is not common for USB devices). Further the
> platform device is only created when CONFIG_USB_ONBOARD_HUB=y/m.
> 
> Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
> ---
> 
> Changes in v5:
> - patch added to the series
> 
>  drivers/usb/host/xhci-plat.c | 16 ++++++++++++++++
>  include/linux/usb/hcd.h      |  2 ++
>  2 files changed, 18 insertions(+)
> 
> diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c
> index 4d34f6005381..e785fa109eea 100644
> --- a/drivers/usb/host/xhci-plat.c
> +++ b/drivers/usb/host/xhci-plat.c
> @@ -15,6 +15,7 @@
>  #include <linux/of.h>
>  #include <linux/of_device.h>
>  #include <linux/platform_device.h>
> +#include <linux/usb/onboard_hub.h>
>  #include <linux/usb/phy.h>
>  #include <linux/slab.h>
>  #include <linux/acpi.h>
> @@ -184,6 +185,7 @@ static int xhci_plat_probe(struct platform_device *pdev)
>  	int			ret;
>  	int			irq;
>  	struct xhci_plat_priv	*priv = NULL;
> +	struct device_node	*np;
>  
>  
>  	if (usb_disabled())
> @@ -356,6 +358,17 @@ static int xhci_plat_probe(struct platform_device *pdev)
>  	 */
>  	pm_runtime_forbid(&pdev->dev);
>  
> +	np = usb_of_get_device_node(hcd->self.root_hub, hcd->self.busnum);
> +	if (np && of_is_onboard_usb_hub(np)) {
> +		struct platform_device *pdev;
> +
> +		pdev = of_platform_device_create(np, NULL, NULL);

A platform device is a child of another platform device?  Ok, but
really, why?  What uses this device?

thanks,

greg k-h