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From:   Douglas Anderson <dianders@chromium.org>
To:     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>
Cc:     Grant Grundler <grundler@chromium.org>,
        Hayes Wang <hayeswang@realtek.com>,
        Simon Horman <horms@kernel.org>,
        =?UTF-8?q?Bj=C3=B8rn=20Mork?= <bjorn@mork.no>,
        netdev@vger.kernel.org, Brian Geffon <bgeffon@google.com>,
        Alan Stern <stern@rowland.harvard.edu>,
        Douglas Anderson <dianders@chromium.org>,
        linux-kernel@vger.kernel.org
Subject: [PATCH net v2 3/3] r8152: Choose our USB config with choose_configuration() rather than probe()
Date:   Fri,  1 Dec 2023 10:29:52 -0800
Message-ID: <20231201102946.v2.3.Ie00e07f07f87149c9ce0b27ae4e26991d307e14b@changeid>
In-Reply-To: <20231201183113.343256-1-dianders@chromium.org>
References: <20231201183113.343256-1-dianders@chromium.org>
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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>
---

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