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Date: Thu, 30 May 2024 00:22:52 +0200
From: Andrew Lunn <andrew@lunn.ch>
To: Andrew Halaney <ahalaney@redhat.com>
Cc: Sagar Cheluvegowda <quic_scheluve@quicinc.com>,
	Vinod Koul <vkoul@kernel.org>,
	Alexandre Torgue <alexandre.torgue@foss.st.com>,
	Jose Abreu <joabreu@synopsys.com>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Maxime Coquelin <mcoquelin.stm32@gmail.com>,
	Jochen Henneberg <jh@henneberg-systemdesign.com>,
	linux-arm-msm@vger.kernel.org, netdev@vger.kernel.org,
	linux-stm32@st-md-mailman.stormreply.com,
	linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] net: stmmac: dwmac-qcom-ethqos: Configure host DMA width
Message-ID: <d8ad4e59-5725-4a7d-a2ad-ce5d92553525@lunn.ch>
References: <20240529-configure_ethernet_host_dma_width-v1-1-3f2707851adf@quicinc.com>
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On Wed, May 29, 2024 at 03:50:28PM -0500, Andrew Halaney wrote:
> $Subject should be have [PATCH net] since this targets the net tree:
> 
> https://docs.kernel.org/process/maintainer-netdev.html
> 
> On Wed, May 29, 2024 at 11:39:04AM GMT, Sagar Cheluvegowda wrote:
> > Fixes: 070246e4674b ("net: stmmac: Fix for mismatched host/device DMA address width")
> > Signed-off-by: Sagar Cheluvegowda <quic_scheluve@quicinc.com>

> Also, I think the Fixes: here would be for adding support for this SoC
> in the driver, not what's listed? Might make more sense after you have a
> proper body though.

This is a tricky one. 

Fixes: 070246e4674b ("net: stmmac: Fix for mismatched host/device DMA
address width") is when support for different DMA address widths was
added. This fix cannot easily be back ported past that.

070246e4674b first appears in v6.3-rc4.

dwmac-qcom-ethqos.c first appears in v5.1-rc1. However, Qualcomm did
not start hacking on it until v6.7-rc6. It is unclear to me without a
deep dive when Qualcomm actually started using this driver.

We might actually be looking at this the wrong way, and should in fact
be looking at when a DT patch was added that made use of the driver,
not the driver itself. If it was not used, it cannot be broken....

	Andrew