Re: [PATCH 11/30] PCI: tegra: Increase the deskew retry time

[Thierry Reding <thierry.reding@gmail.com>]

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On Thu, Apr 11, 2019 at 10:33:36PM +0530, Manikanta Maddireddy wrote:
> Some times link speed change from Gen2 to Gen1 fails due to instability

"Sometimes"

> in deskew logic on lane-0 in Tegra210. Increase the deskew retry time
> to resolve this issue.
> 
> Signed-off-by: Manikanta Maddireddy <mmaddireddy@nvidia.com>
> ---
>  drivers/pci/controller/pci-tegra.c | 28 ++++++++++++++++++++++++++++
>  1 file changed, 28 insertions(+)
> 
> diff --git a/drivers/pci/controller/pci-tegra.c b/drivers/pci/controller/pci-tegra.c
> index f785ecae2f6b..9e61da68cfae 100644
> --- a/drivers/pci/controller/pci-tegra.c
> +++ b/drivers/pci/controller/pci-tegra.c
> @@ -209,6 +209,10 @@
>  #define  RP_VEND_XP_OPPORTUNISTIC_ACK		(1 << 27)
>  #define  RP_VEND_XP_OPPORTUNISTIC_UPDATEFC	(1 << 28)
>  
> +#define RP_VEND_CTL0	0x00000f44
> +#define  RP_VEND_CTL0_DSK_RST_PULSE_WIDTH_MASK	(0xf << 12)
> +#define  RP_VEND_CTL0_DSK_RST_PULSE_WIDTH	(0x9 << 12)
> +
>  #define RP_VEND_CTL1	0x00000f48
>  #define  RP_VEND_CTL1_ERPT	(1 << 13)
>  
> @@ -304,6 +308,7 @@ struct tegra_pcie_soc {
>  	bool force_pca_enable;
>  	bool program_uphy;
>  	bool update_clamp_threshold;
> +	bool program_deskew_time;
>  	struct {
>  		struct {
>  			u32 rp_ectl_2_r1;
> @@ -615,6 +620,23 @@ static void tegra_pcie_program_ectl_settings(struct tegra_pcie_port *port)
>  	writel(val, port->base + RP_ECTL_6_R2);
>  }
>  
> +static void tegra_pcie_apply_sw_fixup(struct tegra_pcie_port *port)
> +{
> +	const struct tegra_pcie_soc *soc = port->pcie->soc;
> +	u32 value;
> +
> +	/*
> +	 * Tune deskew retry time to take care of Gen2 -> Gen1
> +	 * link speed change error in corner cases
> +	 */
> +	if (soc->program_deskew_time) {
> +		value = readl(port->base + RP_VEND_CTL0);
> +		value &= ~RP_VEND_CTL0_DSK_RST_PULSE_WIDTH_MASK;
> +		value |= RP_VEND_CTL0_DSK_RST_PULSE_WIDTH;
> +		writel(value, port->base + RP_VEND_CTL0);
> +	}
> +}
> +
>  static void tegra_pcie_port_enable(struct tegra_pcie_port *port)
>  {
>  	unsigned long ctrl = tegra_pcie_port_get_pex_ctrl(port);
> @@ -643,6 +665,7 @@ static void tegra_pcie_port_enable(struct tegra_pcie_port *port)
>  	tegra_pcie_enable_rp_features(port);
>  	if (soc->ectl.enable)
>  		tegra_pcie_program_ectl_settings(port);
> +	tegra_pcie_apply_sw_fixup(port);

Blank line between the above two for readability.

Thierry

>  }
>  
>  static void tegra_pcie_port_disable(struct tegra_pcie_port *port)
> @@ -2357,6 +2380,7 @@ static const struct tegra_pcie_soc tegra20_pcie = {
>  	.force_pca_enable = false,
>  	.program_uphy = true,
>  	.update_clamp_threshold = false,
> +	.program_deskew_time = false,
>  	.ectl.enable = false,
>  };
>  
> @@ -2382,6 +2406,7 @@ static const struct tegra_pcie_soc tegra30_pcie = {
>  	.force_pca_enable = false,
>  	.program_uphy = true,
>  	.update_clamp_threshold = false,
> +	.program_deskew_time = false,
>  	.ectl.enable = false,
>  };
>  
> @@ -2400,6 +2425,7 @@ static const struct tegra_pcie_soc tegra124_pcie = {
>  	.force_pca_enable = false,
>  	.program_uphy = true,
>  	.update_clamp_threshold = true,
> +	.program_deskew_time = false,
>  	.ectl.enable = false,
>  };
>  
> @@ -2418,6 +2444,7 @@ static const struct tegra_pcie_soc tegra210_pcie = {
>  	.force_pca_enable = true,
>  	.program_uphy = true,
>  	.update_clamp_threshold = true,
> +	.program_deskew_time = true,
>  	.ectl.regs.rp_ectl_2_r1 = 0x0000000f,
>  	.ectl.regs.rp_ectl_4_r1 = 0x00000067,
>  	.ectl.regs.rp_ectl_5_r1 = 0x55010000,
> @@ -2451,6 +2478,7 @@ static const struct tegra_pcie_soc tegra186_pcie = {
>  	.force_pca_enable = false,
>  	.program_uphy = false,
>  	.update_clamp_threshold = false,
> +	.program_deskew_time = false,
>  	.ectl.enable = false,
>  };
>  
> -- 
> 2.17.1
> 

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