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Date:   Fri, 1 Dec 2023 14:28:46 -0500
From:   Alan Stern <stern@rowland.harvard.edu>
To:     Douglas Anderson <dianders@chromium.org>
Cc:     linux-usb@vger.kernel.org,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "David S . Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Grant Grundler <grundler@chromium.org>,
        Hayes Wang <hayeswang@realtek.com>,
        Simon Horman <horms@kernel.org>,
        =?iso-8859-1?Q?Bj=F8rn?= Mork <bjorn@mork.no>,
        netdev@vger.kernel.org, Brian Geffon <bgeffon@google.com>,
        Hans de Goede <hdegoede@redhat.com>,
        Heikki Krogerus <heikki.krogerus@linux.intel.com>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 1/3] usb: core: Don't force USB generic_subclass
 drivers to define probe()
Message-ID: <59c5c190-234c-42d4-9a44-eadba4b717f0@rowland.harvard.edu>
References: <20231201183113.343256-1-dianders@chromium.org>
 <20231201102946.v2.1.I7ea0dd55ee2acdb48b0e6d28c1a704ab2c29206f@changeid>
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On Fri, Dec 01, 2023 at 10:29:50AM -0800, Douglas Anderson wrote:
> There's no real reason that subclassed USB drivers _need_ to define
> probe() since they might want to subclass for some other reason. Make
> it optional to define probe() if we're a generic_subclass.
> 
> Signed-off-by: Douglas Anderson <dianders@chromium.org>
> ---

Reviewed-by: Alan Stern <stern@rowland.harvard.edu>

> Changes in v2:
> - ("Don't force USB generic_subclass drivers to define ...") new for v2.
> 
>  drivers/usb/core/driver.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
> index f58a0299fb3b..1dc0c0413043 100644
> --- a/drivers/usb/core/driver.c
> +++ b/drivers/usb/core/driver.c
> @@ -290,7 +290,10 @@ static int usb_probe_device(struct device *dev)
>  	 * specialised device drivers prior to setting the
>  	 * use_generic_driver bit.
>  	 */
> -	error = udriver->probe(udev);
> +	if (udriver->probe)
> +		error = udriver->probe(udev);
> +	else if (!udriver->generic_subclass)
> +		error = -EINVAL;
>  	if (error == -ENODEV && udriver != &usb_generic_driver &&
>  	    (udriver->id_table || udriver->match)) {
>  		udev->use_generic_driver = 1;
> -- 
> 2.43.0.rc2.451.g8631bc7472-goog
>