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[ Upstream commit 3a53285228165225a7f76c7d5ff1ddc0213ce0e4 ] Problem description: After ethernet cable connect and disconnect for several iterations on a device with i210, tx timestamp will stop being put into the socket. Steps to reproduce: 1. Setup a device with i210 and wire it to a 802.1AS capable switch ( Extreme Networks Summit x440 is used in our case) 2. Have the gptp daemon running on the device and make sure it is synced with the switch 3. Have the switch disable and enable the port, wait for the device gets resynced with the switch 4. Iterates step 3 until the device is not albe to get resynced 5. Review the log in dmesg and you will see warning message "igb : clearing Tx timestamp hang" Root cause: If ptp_tx_work() gets scheduled just before the port gets disabled, a LINK DOWN event will be processed before ptp_tx_work(), which may cause timeout in ptp_tx_work(). In the timeout logic, the TSYNCTXCTL's TXTT bit (Transmit timestamp valid bit) is not cleared, causing no new timestamp loaded to TXSTMP register. Consequently therefore, no new interrupt is triggerred by TSICR.TXTS bit and no more Tx timestamp send to the socket. Signed-off-by: Daniel Hua <daniel.hua@ni.com> Tested-by: Aaron Brown <aaron.f.brown@intel.com> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com> Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.