Re: [PATCH net] net: stmmac: work around sporadic tx issue on link-up

From: Heiner Kallweit <hkallweit1@gmail.com>
To: Jakub Kicinski <kuba@kernel.org>
Cc: Giuseppe Cavallaro <peppe.cavallaro@st.com>,
	Alexandre Torgue <alexandre.torgue@foss.st.com>,
	Jose Abreu <joabreu@synopsys.com>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Paolo Abeni <pabeni@redhat.com>,
	Maxime Coquelin <mcoquelin.stm32@gmail.com>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"moderated list:ARM/STM32 ARCHITECTURE"
	<linux-stm32@st-md-mailman.stormreply.com>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	Qi Duan <qi.duan@amlogic.com>, Da Xue <da@lessconfused.com>,
	Jerome Brunet <jbrunet@baylibre.com>
Subject: Re: [PATCH net] net: stmmac: work around sporadic tx issue on link-up
Date: Wed, 24 Aug 2022 22:36:27 +0200	[thread overview]
Message-ID: <776ece87-e24c-bb19-e472-8a04d1cbbaa3@gmail.com> (raw)
In-Reply-To: <20220823162259.36401af0@kernel.org>

On 24.08.2022 01:22, Jakub Kicinski wrote:
> On Sat, 20 Aug 2022 17:20:37 +0200 Heiner Kallweit wrote:
>> 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.
>>
>> This patch doesn't apply cleanly before the commit marked as fixed.
>> There's nothing wrong with this commit.
> 
> I don't think this is right, please do your best to identify where
> the bug was actually introduced and put that in the Fixes tag.
> 
> IIRC this is not the first time you've made this choice so let's
> sort this out, we can bring it up with Greg if you would like,
> I don't see it clarified in the docs.
> 
> My understanding and experience doing backports for my employer is 
> that cutting off the Fixes tag at the place patch application fails 
> is very counter productive. Better to go too far back and let 
> the person maintaining the tree decide if the backport is needed.
> 
OK, I changed the Fixes tag accordingly and submitted a v2.

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel