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Subject: Re: [PATCH] btusb: CSR chip hangs when unbound
From:   Marcel Holtmann <marcel@holtmann.org>
In-Reply-To: <20220429114113.356263-1-jtornosm@redhat.com>
Date:   Fri, 29 Apr 2022 16:49:03 +0200
Cc:     Johan Hedberg <johan.hedberg@gmail.com>,
        Luiz Augusto von Dentz <luiz.dentz@gmail.com>,
        linux-bluetooth@vger.kernel.org
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Message-Id: <B8BA4391-6F9D-4D3A-AF30-C2A3FC399D1D@holtmann.org>
References: <20220429114113.356263-1-jtornosm@redhat.com>
To:     Jose Ignacio Tornos Martinez <jtornosm@redhat.com>
Precedence: bulk

Hi Jose,

> Bluetooth Dongles with CSR chip (i.e. USB Bluetooth V4.0 Dongle by Trust)
> hang when they are unbound from 'unbind' sysfs entry and can not be bound
> again.
> 
> The reason is CSR chip hangs when usb configuration command with index 0 
> (used to unconfigure) is sent during disconnection.
> 
> To avoid this unwanted result, it is necessary not to send this command 
> for CSR chip when usb device is unbound. Besides, "skip_unconfigure"  sysfs 
> entry has been created for testing purposes with these or other devices.
> 
> Athough device is not unconfigured, it is better to avoid device hanging to
> be able to operate. Even bluetooth can be previously turned off.
> On the other hand, this is not important if usb device is going to be bound 
> again (normal behavior), i.e. with usbip.
> 
> Signed-off-by: Jose Ignacio Tornos Martinez <jtornosm@redhat.com>
> ---
> drivers/bluetooth/btusb.c  |  6 ++++++
> drivers/usb/core/generic.c |  2 +-
> drivers/usb/core/sysfs.c   | 36 ++++++++++++++++++++++++++++++++++++
> include/linux/usb.h        |  2 ++
> 4 files changed, 45 insertions(+), 1 deletion(-)

send this to the USB guys first and get their ACK.

Regards

Marcel