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

From: Mark Rutland
Date: Mon Feb 09 2015 - 07:05:31 EST


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 <chenbaozi@xxxxxxxxxxxxxx>
> ---
> 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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