Subject: Re: [PATCH 3/3] stmmac: Add AXI burst length support to platform device.

From: Mark Rutland <[email-masked]>
Date: Mon, 9 Feb 2015 12:04:43 +0000

On Sat, Feb 07, 2015 at 05:07:16AM +0000, Chen Baozi wrote:
> The AXI Bus Mode Register controls the AXI master behavior. It is mainly
> used to control the burst splitting and the number of outstanding requests.
> This register is present and valid only in GMAC-AXI configuration. The old
> driver only supports this feature on PCI devices. This patch adds an
> 'snps,apl' properties in DT to enable it on platform devices.
> 
> Signed-off-by: Chen Baozi <[email-masked]>
> ---
>  Documentation/devicetree/bindings/net/stmmac.txt      | 1 +
>  drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c | 1 +
>  2 files changed, 2 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/net/stmmac.txt b/Documentation/devicetree/bindings/net/stmmac.txt
> index c41afd9..8f3c834 100644
> --- a/Documentation/devicetree/bindings/net/stmmac.txt
> +++ b/Documentation/devicetree/bindings/net/stmmac.txt
> @@ -43,6 +43,7 @@ Optional properties:
>    available this clock is used for programming the Timestamp Addend Register.
>    If not passed then the system clock will be used and this is fine on some
>    platforms.
> +- snps,abl: AXI Burst Length

This is not a good name (though I see it follows "snps,pbl", which is
also not a good name)...

Why does this need to be in the DT? Is this required for correctness? Or
performance?

Thanks,
Mark.

>  
>  Examples:
>  
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
> index 3039de2..abbc897 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
> @@ -230,6 +230,7 @@ static int stmmac_probe_config_dt(struct platform_device *pdev,
>  			return -ENOMEM;
>  		plat->dma_cfg = dma_cfg;
>  		of_property_read_u32(np, "snps,pbl", &dma_cfg->pbl);
> +		of_property_read_u32(np, "snps,abl", &dma_cfg->burst_len);
>  		dma_cfg->fixed_burst =
>  			of_property_read_bool(np, "snps,fixed-burst");
>  		dma_cfg->mixed_burst =
> -- 
> 2.1.4
> 
> 
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