Re: [PATCH 06/12] PCI: tegra: Enable opportunistic update FC and ACK

[Vidya Sagar <vidyas-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>]

On Saturday 28 October 2017 12:59 AM, Manikanta Maddireddy wrote:
> This patch ensures that DL sends pending ACKs and update FC packets when
> link is idle instead of waiting for timers to expire which improves PCIe
> bandwidth.
>
> Signed-off-by: Manikanta Maddireddy <mmaddireddy-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
> ---
>   drivers/pci/host/pci-tegra.c | 15 ++++++++++++++-
>   1 file changed, 14 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/pci/host/pci-tegra.c b/drivers/pci/host/pci-tegra.c
> index af34daf3c6a2..27a8211c48b2 100644
> --- a/drivers/pci/host/pci-tegra.c
> +++ b/drivers/pci/host/pci-tegra.c
> @@ -209,7 +209,9 @@
>   #define  RP_ECTL_6_R2_RX_EQ_CTRL_H_1C_MASK	0xffffffff
>   
>   #define RP_VEND_XP	0x00000f00
> -#define  RP_VEND_XP_DL_UP	(1 << 30)
> +#define  RP_VEND_XP_DL_UP			(1 << 30)
> +#define  RP_VEND_XP_OPPORTUNISTIC_ACK		(1 << 27)
> +#define  RP_VEND_XP_OPPORTUNISTIC_UPDATEFC	(1 << 28)
>   
BIT macro is preferred here.
>   #define RP_VEND_CTL1	0xf48
>   #define  RP_VEND_CTL1_ERPT	(1 << 13)
> @@ -2147,6 +2149,16 @@ static void tegra_pcie_enable_rp_features(struct tegra_pcie_port *port)
>   	writel(value, port->base + RP_VEND_CTL1);
>   }
>   
> +static void tegra_pcie_apply_sw_fixup(struct tegra_pcie_port *port)
> +{
> +	unsigned long value;
> +
> +	/* Optimal settings to enhance bandwidth */
> +	value = readl(port->base + RP_VEND_XP);
> +	value |= RP_VEND_XP_OPPORTUNISTIC_ACK;
> +	value |= RP_VEND_XP_OPPORTUNISTIC_UPDATEFC;
> +	writel(value, port->base + RP_VEND_XP);
> +}
>   /*
>    * FIXME: If there are no PCIe cards attached, then calling this function
>    * can result in the increase of the bootup time as there are big timeout
> @@ -2215,6 +2227,7 @@ static void tegra_pcie_enable_ports(struct tegra_pcie *pcie)
>   		if (soc->program_ectl_settings)
>   			tegra_pcie_program_ectl_settings(port);
>   		tegra_pcie_enable_rp_features(port);
> +		tegra_pcie_apply_sw_fixup(port);
>   	}
>   
>   	/* take the PCIe interface module out of reset */