On Tue, Aug 27, 2019 at 09:54:17PM +0530, Vidya Sagar wrote:

On 8/27/2019 9:17 PM, Andrew Murray wrote:

quoted

On Mon, Aug 26, 2019 at 01:01:43PM +0530, Vidya Sagar wrote:

quoted

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 <redacted>
---
  drivers/pci/controller/dwc/pcie-tegra194.c | 65 ++++++++++++++++++++++
  1 file changed, 65 insertions(+)

diff --git a/drivers/pci/controller/dwc/pcie-tegra194.c b/drivers/pci/controller/dwc/pcie-tegra194.c
index 8a27b25893c9..97de2151a738 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 +1049,59 @@ static void tegra_pcie_downstream_dev_to_D0(struct tegra_pcie_dw *pcie)
  	}
  }
+static void 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))
+		pcie->slot_ctl_3v3 = NULL;
+
+	pcie->slot_ctl_12v = devm_regulator_get_optional(pcie->dev, "vpcie12v");
+	if (IS_ERR(pcie->slot_ctl_12v))
+		pcie->slot_ctl_12v = NULL;

Do these need to take into consideration -EPROBE_DEFER?

Since these are devm_* APIs, isn't it taken care of automatically?

devm_regulator_get_optional can still return -EPROBE_DEFER - for times when
"lookup could succeed in the future".

It's probably helpful here for your driver to distinguish between there not
being a regulator specified in the DT, and there being a regulator but there
is no device for it yet. For the latter case - your driver would probe but
nothing would enumerate.

See pcie-rockchip-host.c for an example of where this is handled.

Of course if, for whatever reason it is unlikely you'll ever get -EPROBE_DEFER
then maybe it's OK as it is.

Thanks,

Andrew Murray

quoted

Thanks,

Andrew Murray

quoted

+}
+
+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);
+			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);
+			if (pcie->slot_ctl_3v3)
+				regulator_disable(pcie->slot_ctl_3v3);
+			return ret;
+		}
+	}
+
+	/*
+	 * 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);
+
+	return 0;
+}
+
+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 +1115,10 @@ 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 +1201,8 @@ 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 +1235,8 @@ 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",

@@ -1372,6 +1435,8 @@ static int tegra_pcie_dw_probe(struct platform_device *pdev)
  		return ret;
  	}
+	tegra_pcie_get_slot_regulators(pcie);
+
  	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

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel