linux-kernel - Re: [PATCH v17 1/7] usb: misc: Add onboard_usb

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Date:   Wed, 17 Nov 2021 16:11:34 -0800
From:   Doug Anderson <dianders@...omium.org>
To:     Matthias Kaehlcke <mka@...omium.org>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Alan Stern <stern@...land.harvard.edu>,
        Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Mathias Nyman <mathias.nyman@...el.com>,
        Felipe Balbi <balbi@...nel.org>, linux-kernel@...r.kernel.org,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Stephen Boyd <swboyd@...omium.org>,
        Peter Chen <peter.chen@...nel.org>, linux-usb@...r.kernel.org,
        devicetree@...r.kernel.org, Roger Quadros <rogerq@...nel.org>,
        Michal Simek <michal.simek@...inx.com>,
        Ravi Chandra Sadineni <ravisadineni@...omium.org>,
        Bastien Nocera <hadess@...ess.net>
Subject: Re: [PATCH v17 1/7] usb: misc: Add onboard_usb_hub driver

Hi,

On Tue, Nov 16, 2021 at 12:07 PM Matthias Kaehlcke <mka@...omium.org> wrote:
>
> --- a/drivers/usb/misc/Kconfig
> +++ b/drivers/usb/misc/Kconfig
> @@ -284,3 +284,20 @@ config BRCM_USB_PINMAP
>           This option enables support for remapping some USB external
>           signals, which are typically on dedicated pins on the chip,
>           to any gpio.
> +
> +config USB_ONBOARD_HUB
> +       tristate "Onboard USB hub support"

Aren't you back to shenanigans now that you're being called straight
from the USB core? What if you're a module and the USB core is
builtin? It can't call you, right? ...or what if you're builtin but
the USB core is a module (yeah, I know that sounds insane but I don't
think anything technically prevents it)?

Can you just add a dependency here such that if the USB core is a
module that you're a module and if the USB core is builtin that you're
builtin?


> +void onboard_hub_create_pdevs(struct usb_device *parent_hub, struct list_head *pdev_list)
> +{
> +       int i;
> +       struct device_node *np, *npc;
> +       struct platform_device *pdev;
> +       struct pdev_list_entry *pdle;
> +
> +       INIT_LIST_HEAD(pdev_list);
> +
> +       for (i = 1; i <= parent_hub->maxchild; i++) {
> +               np = usb_of_get_device_node(parent_hub, i);
> +               if (!np)
> +                       continue;
> +
> +               if (!of_is_onboard_usb_hub(np))
> +                       goto node_put;
> +
> +               npc = of_parse_phandle(np, "companion-hub", 0);
> +               if (!npc)
> +                       goto create_pdev;
> +
> +               pdev = of_find_device_by_node(npc);
> +               of_node_put(npc);
> +
> +               if (pdev) {
> +                       /* the companion hub already has a platform device, nothing to do here */
> +                       put_device(&pdev->dev);
> +                       goto node_put;
> +               }
> +
> +create_pdev:

I don't really like this "goto". I'd rather just use an "if" test for
the few lines even if the indentation gets to be a bit much.

-Doug