Re: [PATCH V2 4/6] PCI: tegra: Add support to enable slot regulators

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

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On Wed, Aug 28, 2019 at 06:45:03PM +0530, Vidya Sagar wrote:
> Add support to get regulator information of 3.3V and 12V supplies of a PCIe
> slot from the respective controller's device-tree node and enable those
> supplies. This is required in platforms like p2972-0000 where the supplies
> to x16 slot owned by C5 controller need to be enabled before attempting to
> enumerate the devices.
> 
> Signed-off-by: Vidya Sagar <vidyas@nvidia.com>
> ---
> V2:
> * Addressed review comments from Thierry Reding and Andrew Murray
> * Handled failure case of devm_regulator_get_optional() for -ENODEV cleanly
> 
>  drivers/pci/controller/dwc/pcie-tegra194.c | 80 ++++++++++++++++++++++
>  1 file changed, 80 insertions(+)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-tegra194.c b/drivers/pci/controller/dwc/pcie-tegra194.c
> index 057ba4f9fbcd..6a66101ec83d 100644
> --- a/drivers/pci/controller/dwc/pcie-tegra194.c
> +++ b/drivers/pci/controller/dwc/pcie-tegra194.c
> @@ -278,6 +278,8 @@ struct tegra_pcie_dw {
>  	u32 aspm_l0s_enter_lat;
>  
>  	struct regulator *pex_ctl_supply;
> +	struct regulator *slot_ctl_3v3;
> +	struct regulator *slot_ctl_12v;
>  
>  	unsigned int phy_count;
>  	struct phy **phys;
> @@ -1047,6 +1049,72 @@ static void tegra_pcie_downstream_dev_to_D0(struct tegra_pcie_dw *pcie)
>  	}
>  }
>  
> +static int tegra_pcie_get_slot_regulators(struct tegra_pcie_dw *pcie)
> +{
> +	pcie->slot_ctl_3v3 = devm_regulator_get_optional(pcie->dev, "vpcie3v3");
> +	if (IS_ERR(pcie->slot_ctl_3v3)) {
> +		if (PTR_ERR(pcie->slot_ctl_3v3) != -ENODEV)
> +			return PTR_ERR(pcie->slot_ctl_3v3);
> +
> +		pcie->slot_ctl_3v3 = NULL;
> +	}
> +
> +	pcie->slot_ctl_12v = devm_regulator_get_optional(pcie->dev, "vpcie12v");
> +	if (IS_ERR(pcie->slot_ctl_12v)) {
> +		if (PTR_ERR(pcie->slot_ctl_12v) != -ENODEV)
> +			return PTR_ERR(pcie->slot_ctl_12v);
> +
> +		pcie->slot_ctl_12v = NULL;
> +	}
> +
> +	return 0;
> +}
> +
> +static int tegra_pcie_enable_slot_regulators(struct tegra_pcie_dw *pcie)
> +{
> +	int ret;
> +
> +	if (pcie->slot_ctl_3v3) {
> +		ret = regulator_enable(pcie->slot_ctl_3v3);
> +		if (ret < 0) {
> +			dev_err(pcie->dev,
> +				"Failed to enable 3V3 slot supply: %d\n", ret);

Nit: perhaps make this error message "Failed to enable 3.3V slot
supply"? Seems somewhat more user-friendly than 3V3.


> +			return ret;
> +		}
> +	}
> +
> +	if (pcie->slot_ctl_12v) {
> +		ret = regulator_enable(pcie->slot_ctl_12v);
> +		if (ret < 0) {
> +			dev_err(pcie->dev,
> +				"Failed to enable 12V slot supply: %d\n", ret);
> +			goto fail_12v_enable;
> +		}
> +	}
> +
> +	/*
> +	 * According to PCI Express Card Electromechanical Specification
> +	 * Revision 1.1, Table-2.4, T_PVPERL (Power stable to PERST# inactive)
> +	 * should be a minimum of 100ms.
> +	 */
> +	msleep(100);

Do you perhaps want to guard this with something like:

	if (pcie->slot_ctl_3v3 || pcie->slot_ctl_12v)

? Doesn't seem useful to me to sleep 100 ms here if there are no
regulators being enabled to begin with.

Thierry

> +
> +	return 0;
> +
> +fail_12v_enable:
> +	if (pcie->slot_ctl_3v3)
> +		regulator_disable(pcie->slot_ctl_3v3);
> +	return ret;
> +}
> +
> +static void tegra_pcie_disable_slot_regulators(struct tegra_pcie_dw *pcie)
> +{
> +	if (pcie->slot_ctl_12v)
> +		regulator_disable(pcie->slot_ctl_12v);
> +	if (pcie->slot_ctl_3v3)
> +		regulator_disable(pcie->slot_ctl_3v3);
> +}
> +
>  static int tegra_pcie_config_controller(struct tegra_pcie_dw *pcie,
>  					bool en_hw_hot_rst)
>  {
> @@ -1060,6 +1128,10 @@ static int tegra_pcie_config_controller(struct tegra_pcie_dw *pcie,
>  		return ret;
>  	}
>  
> +	ret = tegra_pcie_enable_slot_regulators(pcie);
> +	if (ret < 0)
> +		goto fail_slot_reg_en;
> +
>  	ret = regulator_enable(pcie->pex_ctl_supply);
>  	if (ret < 0) {
>  		dev_err(pcie->dev, "Failed to enable regulator: %d\n", ret);
> @@ -1142,6 +1214,8 @@ static int tegra_pcie_config_controller(struct tegra_pcie_dw *pcie,
>  fail_core_clk:
>  	regulator_disable(pcie->pex_ctl_supply);
>  fail_reg_en:
> +	tegra_pcie_disable_slot_regulators(pcie);
> +fail_slot_reg_en:
>  	tegra_pcie_bpmp_set_ctrl_state(pcie, false);
>  
>  	return ret;
> @@ -1174,6 +1248,8 @@ static int __deinit_controller(struct tegra_pcie_dw *pcie)
>  		return ret;
>  	}
>  
> +	tegra_pcie_disable_slot_regulators(pcie);
> +
>  	ret = tegra_pcie_bpmp_set_ctrl_state(pcie, false);
>  	if (ret) {
>  		dev_err(pcie->dev, "Failed to disable controller %d: %d\n",
> @@ -1373,6 +1449,10 @@ static int tegra_pcie_dw_probe(struct platform_device *pdev)
>  		return ret;
>  	}
>  
> +	ret = tegra_pcie_get_slot_regulators(pcie);
> +	if (ret < 0)
> +		return ret;
> +
>  	pcie->pex_ctl_supply = devm_regulator_get(dev, "vddio-pex-ctl");
>  	if (IS_ERR(pcie->pex_ctl_supply)) {
>  		dev_err(dev, "Failed to get regulator: %ld\n",
> -- 
> 2.17.1
> 

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