net: stmmac: work around sporadic tx issue on link-up

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[ Upstream commit a3a57bf07d ]

This is a follow-up to the discussion in [0]. It seems to me that
at least the IP version used on Amlogic SoC's sometimes has a problem
if register MAC_CTRL_REG is written whilst the chip is still processing
a previous write. But that's just a guess.
Adding a delay between two writes to this register helps, but we can
also simply omit the offending second write. This patch uses the second
approach and is based on a suggestion from Qi Duan.
Benefit of this approach is that we can save few register writes, also
on not affected chip versions.

[0] https://www.spinics.net/lists/netdev/msg831526.html

Fixes: bfab27a146 ("stmmac: add the experimental PCI support")
Suggested-by: Qi Duan <qi.duan@amlogic.com>
Suggested-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Link: https://lore.kernel.org/r/e99857ce-bd90-5093-ca8c-8cd480b5a0a2@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

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This commit is contained in:

Heiner Kallweit 2022-08-24 22:34:49 +02:00 • committed by Greg Kroah-Hartman

parent c830d71201

commit 27a5ab8fec

2 changed files with 11 additions and 6 deletions

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8

drivers/net/ethernet/stmicro/stmmac/dwmac_lib.c

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9

drivers/net/ethernet/stmicro/stmmac/stmmac_main.c

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