r8169: fix rtl8125b PAUSE frames blasting when suspended

[ Upstream commit 4b0768b6 ]

When FIFO reaches near full state, device will issue pause frame.
If pause slot is enabled(set to 1), in this time, device will issue
pause frame only once. But if pause slot is disabled(set to 0), device
will keep sending pause frames until FIFO reaches near empty state.

When pause slot is disabled, if there is no one to handle receive
packets, device FIFO will reach near full state and keep sending
pause frames. That will impact entire local area network.

This issue can be reproduced in Chromebox (not Chromebook) in
developer mode running a test image (and v5.10 kernel):
1) ping -f $CHROMEBOX (from workstation on same local network)
2) run "powerd_dbus_suspend" from command line on the $CHROMEBOX
3) ping $ROUTER (wait until ping fails from workstation)

Takes about ~20-30 seconds after step 2 for the local network to
stop working.

Fix this issue by enabling pause slot to only send pause frame once
when FIFO reaches near full state.

Fixes: f1bce4ad ("r8169: add support for RTL8125")
Reported-by: Grant Grundler <grundler@chromium.org>
Tested-by: Grant Grundler <grundler@chromium.org>
Cc: stable@vger.kernel.org
Signed-off-by: ChunHao Lin <hau@realtek.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Heiner Kallweit <hkallweit1@gmail.com>
Link: https://lore.kernel.org/r/20231129155350.5843-1-hau@realtek.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>