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Message-Id: <20131127005739.317843009@linuxfoundation.org> Date: Tue, 26 Nov 2013 16:56:47 -0800 From: Greg Kroah-Hartman <gregkh@...uxfoundation.org> To: linux-kernel@...r.kernel.org Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, stable@...r.kernel.org, Shuah Khan <shuah.kh@...sung.com>, Gustavo Padovan <gustavo.padovan@...labora.co.uk>, Hans de Goede <hdegoede@...hat.com> Subject: [PATCH 3.12 034/116] Bluetooth: revert: "Bluetooth: Add missing reset_resume dev_pm_ops" 3.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Hans de Goede <hdegoede@...hat.com> commit b1a8014471b01dd862de9f91bbbff1296afac42d upstream. Many btusb devices have 2 modes, a hid mode and a bluetooth hci mode. These devices default to hid mode for BIOS use. This means that after having been reset they will revert to HID mode, and are no longer usable as a HCI. Therefor it is a very bad idea to just blindly make reset_resume point to the regular resume handler. Note that the btusb driver has no clue how to switch these devices from hid to hci mode, this is done in userspace through udev rules, so the proper way to deal with this is to not have a reset-resume handler and instead let the usb-system re-enumerate the device, and re-run the udev rules. I must also note, that the commit message for the commit causing this problem has a very weak motivation for the change: "Add missing reset_resume dev_pm_ops. Missing reset_resume results in the following message after power management device test. This change sets reset_resume to btusb_resume(). [ 2506.936134] btusb 1-1.5:1.0: no reset_resume for driver btusb? [ 2506.936137] btusb 1-1.5:1.1: no reset_resume for driver btusb?" Making a change solely to silence a warning while also changing important behavior (normal resume handling versus re-enumeration) requires a commit message with a proper explanation why it is safe to do so, which clearly lacks here, and unsurprisingly it turns out to not be safe to make this change. Reverting the commit in question fixes bt no longer working on my Dell E6430 after a suspend/resume, and I believe it likely also fixes the following bugs: https://bugzilla.redhat.com/show_bug.cgi?id=988481 https://bugzilla.redhat.com/show_bug.cgi?id=1010649 https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1213239 This reverts commit 502f769662978a2fe99d0caed5e53e3006107381. Cc: Shuah Khan <shuah.kh@...sung.com> Cc: Gustavo Padovan <gustavo.padovan@...labora.co.uk> Signed-off-by: Hans de Goede <hdegoede@...hat.com> Signed-off-by: Gustavo Padovan <gustavo.padovan@...labora.co.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org> --- drivers/bluetooth/btusb.c | 1 - 1 file changed, 1 deletion(-) --- a/drivers/bluetooth/btusb.c +++ b/drivers/bluetooth/btusb.c @@ -1628,7 +1628,6 @@ static struct usb_driver btusb_driver = #ifdef CONFIG_PM .suspend = btusb_suspend, .resume = btusb_resume, - .reset_resume = btusb_resume, #endif .id_table = btusb_table, .supports_autosuspend = 1, -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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