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Date: Fri, 7 Jun 2024 08:24:00 -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, Andrew Lunn <andrew@lunn.ch>
Subject: Re: [PATCH net v2] net: stmmac: dwmac-qcom-ethqos: Configure host
 DMA width
Message-ID: <jtalwaityx7fyakigggyahhhor23fml76yic3e3xkeoimdqoj2@i7fiqzacowq3>
References: <20240605-configure_ethernet_host_dma_width-v2-1-4cc34edfa388@quicinc.com>
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In-Reply-To: <20240605-configure_ethernet_host_dma_width-v2-1-4cc34edfa388@quicinc.com>

On Wed, Jun 05, 2024 at 11:57:18AM GMT, Sagar Cheluvegowda wrote:
> Commit 070246e4674b ("net: stmmac: Fix for mismatched host/device DMA
> address width") added support in the stmmac driver for platform drivers
> to indicate the host DMA width, but left it up to authors of the
> specific platforms to indicate if their width differed from the addr64
> register read from the MAC itself.
> 
> Qualcomm's EMAC4 integration supports only up to 36 bit width (as
> opposed to the addr64 register indicating 40 bit width). Let's indicate
> that in the platform driver to avoid a scenario where the driver will
> allocate descriptors of size that is supported by the CPU which in our
> case is 36 bit, but as the addr64 register is still capable of 40 bits
> the device will use two descriptors as one address.
> 
> Fixes: 8c4d92e82d50 ("net: stmmac: dwmac-qcom-ethqos: add support for emac4 on sa8775p platforms")
> Signed-off-by: Sagar Cheluvegowda <quic_scheluve@quicinc.com>

Reviewed-by: Andrew Halaney <ahalaney@redhat.com>

> ---
> Changes in v2:
> Fix commit message to include a commit body
> Replace the proper fixes tag
> Remove the change-Id
> - Link to v1: https://lore.kernel.org/r/20240529-configure_ethernet_host_dma_width-v1-1-3f2707851adf@quicinc.com
> ---
>  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>
>