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Message-ID: <0661117fc2ff5f926443513c6685b72b8f371d14.camel@hadess.net>
Subject: Re: [PATCH 4/5] USB: Select better matching USB drivers when
 available
From:   Bastien Nocera <hadess@hadess.net>
To:     Alan Stern <stern@rowland.harvard.edu>
Cc:     linux-usb@vger.kernel.org,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Benjamin Tissoires <benjamin.tissoires@redhat.com>
Date:   Wed, 09 Oct 2019 20:24:19 +0200
In-Reply-To: <Pine.LNX.4.44L0.1910091324300.1603-100000@iolanthe.rowland.org>
References: <Pine.LNX.4.44L0.1910091324300.1603-100000@iolanthe.rowland.org>
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On Wed, 2019-10-09 at 13:28 -0400, Alan Stern wrote:
<snip>
> No, that's not quite it.
> 
> Here's what should happen when the subclass driver is being probed:
> First, call the generic_probe routine, and return immediately if that
> fails.  Then call the subclass driver's probe routine.  If that gets
> an
> error, fail the probe call but tell the device core that the device
> is
> now bound to the generic driver, not to the subclass driver.

So, something like that, on top of the existing patches? (I'm not sure
whether device_driver_attach is the correct call to use here).

-       if (udriver->probe)
-               return udriver->probe(udev);
-       return 0;
+       if (!udriver->probe)
+               return 0;
+       error = udriver->probe(udev);
+       if (error == -ENODEV &&
+           udrv != &usb_generic_driver)
+               return device_driver_attach(usb_generic_driver.drvwrap.driver, dev);
+       return error;

Anything else in this patch series? I was concerned about the naming
for "generic_init" in patch 2 ("subclass").

If there's nothing, I'll test and respin the patchset with the above
changes tomorrow.

Cheers