[Intel-wired-lan] [PATCH] Cover letter for igb: bug fix Tx interrupt is not

[Alexander Duyck]

On Tue, Dec 26, 2017 at 6:17 PM, Daniel Hua <daniel.hua at ni.com> wrote:
> 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.
>
> Daniel Hua (1):
>   igb: bug fix Tx interrupt is not triggered
>
>  drivers/net/ethernet/intel/igb/igb_ptp.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
>
> --

Could you please combine this description of the issue with the patch
itself? It isn't really very useful to have the patch documented in a
cover letter that will never make it into the driver itself.

Thanks.

- Alex