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Message-ID: <20190828162420.GB10422@ulmo>
Date: Wed, 28 Aug 2019 18:24:20 +0200
From: Thierry Reding <thierry.reding@...il.com>
To: Vidya Sagar <vidyas@...dia.com>
Cc: lorenzo.pieralisi@....com, bhelgaas@...gle.com, robh+dt@...nel.org,
jonathanh@...dia.com, andrew.murray@....com, kishon@...com,
gustavo.pimentel@...opsys.com, digetx@...il.com,
mperttunen@...dia.com, linux-pci@...r.kernel.org,
devicetree@...r.kernel.org, linux-tegra@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
kthota@...dia.com, mmaddireddy@...dia.com, sagar.tv@...il.com
Subject: Re: [PATCH V2 4/6] PCI: tegra: Add support to enable slot regulators
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@...dia.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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