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Date: Wed, 29 May 2024 15:50:28 -0500
From: Andrew Halaney <ahalaney@redhat.com>
To: Sagar Cheluvegowda <quic_scheluve@quicinc.com>
Cc: 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: <7w5bibuejmd5kg3ssozaql4urews26kpj57zvsaoq2pva3vrlo@agfxwq5i65pc>
References: <20240529-configure_ethernet_host_dma_width-v1-1-3f2707851adf@quicinc.com>
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In-Reply-To: <20240529-configure_ethernet_host_dma_width-v1-1-3f2707851adf@quicinc.com>

$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>

Please, always write a commit body, even if its simple. Just inferring
from this patch, I am guessing there is some limitation on CPU's DMA
address width that doesn't match up with the MAC's ability? Paint that
picture for us here please! We want to know the _why_ in this section.

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.

> ---
> Change-Id: Ifdf3490c6f0dd55afc062974c05acce42d5fb6a7

I know this is under the ---, so its not actually in the commit, but I'd
not include that at all when submitting. Someone will complain about it
looking like this is from / for a downstream fork. At least checkpatch
doesn't warn about it, but a human probably will :P

> ---
>  drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c
> index e254b21fdb59..65d7370b47d5 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c
> @@ -93,6 +93,7 @@ struct ethqos_emac_driver_data {
>  	bool has_emac_ge_3;
>  	const char *link_clk_name;
>  	bool has_integrated_pcs;
> +	u32 dma_addr_width;
>  	struct dwmac4_addrs dwmac4_addrs;
>  };
>  
> @@ -276,6 +277,7 @@ static const struct ethqos_emac_driver_data emac_v4_0_0_data = {
>  	.has_emac_ge_3 = true,
>  	.link_clk_name = "phyaux",
>  	.has_integrated_pcs = true,
> +	.dma_addr_width = 36,
>  	.dwmac4_addrs = {
>  		.dma_chan = 0x00008100,
>  		.dma_chan_offset = 0x1000,
> @@ -845,6 +847,8 @@ static int qcom_ethqos_probe(struct platform_device *pdev)
>  		plat_dat->flags |= STMMAC_FLAG_RX_CLK_RUNS_IN_LPI;
>  	if (data->has_integrated_pcs)
>  		plat_dat->flags |= STMMAC_FLAG_HAS_INTEGRATED_PCS;
> +	if (data->dma_addr_width)
> +		plat_dat->host_dma_width = data->dma_addr_width;
>  
>  	if (ethqos->serdes_phy) {
>  		plat_dat->serdes_powerup = qcom_ethqos_serdes_powerup;
> 
> ---
> base-commit: 1b10b390d945a19747d75b34a6e01035ac7b9155
> change-id: 20240515-configure_ethernet_host_dma_width-c619d552992d
> 
> Best regards,
> -- 
> Sagar Cheluvegowda <quic_scheluve@quicinc.com>
> 
>