Re: [PATCH net v2 3/3] r8152: Choose our USB config with choose_configuration() rather than probe()

Grant Grundler
2023-12-02T06:28:23Z

On Fri, Dec 1, 2023 at 10:31 AM Douglas Anderson <dianders@chromium.org> wrote:
>
> If you deauthorize the r8152 device (by writing 0 to the "authorized"
> field in sysfs) and then reauthorize it (by writing a 1) then it no
> longer works. This is because when you do the above we lose the
> special configuration that we set in rtl8152_cfgselector_probe().
> Deauthorizing causes the config to be set to -1 and then reauthorizing
> runs the default logic for choosing the best config.
>
> I made an attempt to fix it so that the config is kept across
> deauthorizing / reauthorizing [1] but it was a bit ugly.
>
> Let's instead use the new USB core feature to override
> choose_configuration().
>
> This patch relies upon the patches ("usb: core: Don't force USB
> generic_subclass drivers to define probe()") and ("usb: core: Allow
> subclassed USB drivers to override usb_choose_configuration()")
>
> [1] https://lore.kernel.org/r/20231130154337.1.Ie00e07f07f87149c9ce0b27ae4e26991d307e14b@changeid
>
> Fixes: ec51fbd1b8a2 ("r8152: add USB device driver for config selection")
> Suggested-by: Alan Stern <stern@rowland.harvard.edu>
> Signed-off-by: Douglas Anderson <dianders@chromium.org>

Reviewed-by: Grant Grundler <grundler@chromium.org>

> ---
>
> Changes in v2:
> - ("Choose our USB config with choose_configuration()...) new for v2.
>
> drivers/net/usb/r8152.c | 16 +++++-----------
> 1 file changed, 5 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/net/usb/r8152.c b/drivers/net/usb/r8152.c
> index 2c5c1e91ded6..0da723d11326 100644
> --- a/drivers/net/usb/r8152.c
> +++ b/drivers/net/usb/r8152.c
> @@ -10053,7 +10053,7 @@ static struct usb_driver rtl8152_driver = {
> .disable_hub_initiated_lpm = 1,
> };
>
> -static int rtl8152_cfgselector_probe(struct usb_device *udev)
> +static int rtl8152_cfgselector_choose_configuration(struct usb_device *udev)
> {
> struct usb_host_config *c;
> int i, num_configs;
> @@ -10080,19 +10080,13 @@ static int rtl8152_cfgselector_probe(struct usb_device *udev)
> if (i == num_configs)
> return -ENODEV;
>
> - if (usb_set_configuration(udev, c->desc.bConfigurationValue)) {
> - dev_err(&udev->dev, "Failed to set configuration %d\n",
> - c->desc.bConfigurationValue);
> - return -ENODEV;
> - }
> -
> - return 0;
> + return c->desc.bConfigurationValue;
> }
>
> static struct usb_device_driver rtl8152_cfgselector_driver = {
> - .name = MODULENAME "-cfgselector",
> - .probe = rtl8152_cfgselector_probe,
> - .id_table = rtl8152_table,
> + .name = MODULENAME "-cfgselector",
> + .choose_configuration = rtl8152_cfgselector_choose_configuration,
> + .id_table = rtl8152_table,
> .generic_subclass = 1,
> .supports_autosuspend = 1,
> };
> --
> 2.43.0.rc2.451.g8631bc7472-goog
>