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

Vidya Sagar
2017-10-29T09:41:34Z

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 */