linux-kernel - [PATCH v1 3/6] PCI: brcmstb: Do not turn off regulators if EP can wake up

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Message-Id: <20201125192424.14440-4-james.quinlan@broadcom.com>
Date:   Wed, 25 Nov 2020 14:24:20 -0500
From:   Jim Quinlan <james.quinlan@...adcom.com>
To:     linux-pci@...r.kernel.org,
        Nicolas Saenz Julienne <nsaenzjulienne@...e.de>,
        bcm-kernel-feedback-list@...adcom.com, james.quinlan@...adcom.com
Cc:     Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Rob Herring <robh@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        linux-rpi-kernel@...ts.infradead.org (moderated list:BROADCOM
        BCM2711/BCM2835 ARM ARCHITECTURE),
        linux-arm-kernel@...ts.infradead.org (moderated list:BROADCOM
        BCM2711/BCM2835 ARM ARCHITECTURE),
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH v1 3/6] PCI: brcmstb: Do not turn off regulators if EP can wake up

If any downstream device may wake up during S2/S3 suspend, we do not want
to turn off its power when suspending.

Signed-off-by: Jim Quinlan <james.quinlan@...adcom.com>
---
 drivers/pci/controller/pcie-brcmstb.c | 56 ++++++++++++++++++++++++---
 1 file changed, 50 insertions(+), 6 deletions(-)

diff --git a/drivers/pci/controller/pcie-brcmstb.c b/drivers/pci/controller/pcie-brcmstb.c
index 34d6bad07b66..9b888846f0bc 100644
--- a/drivers/pci/controller/pcie-brcmstb.c
+++ b/drivers/pci/controller/pcie-brcmstb.c
@@ -193,6 +193,7 @@ static inline void brcm_pcie_bridge_sw_init_set_7278(struct brcm_pcie *pcie, u32
 static inline void brcm_pcie_bridge_sw_init_set_generic(struct brcm_pcie *pcie, u32 val);
 static inline void brcm_pcie_perst_set_7278(struct brcm_pcie *pcie, u32 val);
 static inline void brcm_pcie_perst_set_generic(struct brcm_pcie *pcie, u32 val);
+static bool brcm_pcie_link_up(struct brcm_pcie *pcie);
 
 enum {
 	RGR1_SW_INIT_1,
@@ -302,6 +303,7 @@ struct brcm_pcie {
 	void			(*bridge_sw_init_set)(struct brcm_pcie *pcie, u32 val);
 	struct regulator	*regulators[PCIE_REGULATORS_MAX];
 	int			num_regulators;
+	bool			ep_wakeup_capable;
 };
 
 static int brcm_parse_regulators(struct brcm_pcie *pcie)
@@ -324,18 +326,60 @@ static int brcm_parse_regulators(struct brcm_pcie *pcie)
 	return 0;
 }
 
-static void brcm_set_regulators(struct brcm_pcie *pcie, bool on)
+static int pci_dev_may_wakeup(struct pci_dev *dev, void *data)
 {
+	bool *ret = data;
+
+	if (device_may_wakeup(&dev->dev)) {
+		*ret = true;
+		dev_dbg(&dev->dev, "disable cancelled for wake-up device\n");
+	}
+	return (int) *ret;
+}
+
+enum {
+	TURN_OFF,		/* Turn egulators off, unless an EP is wakeup-capable */
+	TURN_OFF_ALWAYS,	/* Turn Regulators off, no exceptions */
+	TURN_ON,		/* Turn regulators on, unless pcie->ep_wakeup_capable */
+};
+
+static void brcm_set_regulators(struct brcm_pcie *pcie, int how)
+{
+	struct pci_host_bridge *bridge = pci_host_bridge_from_priv(pcie);
 	struct device *dev = pcie->dev;
 	int ret, i;
 
 	if (pcie->num_regulators == 0)
 		return;
 
+	if (how == TURN_ON) {
+		if (pcie->ep_wakeup_capable) {
+			/*
+			 * We are resuming from a suspend.  In the
+			 * previous suspend we did not disable the power
+			 * supplies, so there is no need to enable them
+			 * (and falsely increase their usage count).
+			 */
+			pcie->ep_wakeup_capable = false;
+			return;
+		}
+	} else if (how == TURN_OFF) {
+		/*
+		 * If at least one device on this bus is enabled as a
+		 * wake-up source, do not turn off regulators.
+		 */
+		pcie->ep_wakeup_capable = false;
+		if (bridge->bus && brcm_pcie_link_up(pcie)) {
+			pci_walk_bus(bridge->bus, pci_dev_may_wakeup, &pcie->ep_wakeup_capable);
+			if (pcie->ep_wakeup_capable)
+				return;
+		}
+	}
+
 	for (i = 0; i < PCIE_REGULATORS_MAX; i++) {
 		if (!pcie->regulators[i])
 			continue;
-		if (on) {
+		if (how == TURN_ON) {
 			ret = regulator_enable(pcie->regulators[i]);
 			dev_dbg(dev, "enable regulator %s (%s)\n",
 				ep_regulator_names[i], ret ? "fail" : "pass");
@@ -1197,7 +1241,7 @@ static int brcm_pcie_suspend(struct device *dev)
 	brcm_pcie_turn_off(pcie);
 	ret = brcm_phy_stop(pcie);
 	clk_disable_unprepare(pcie->clk);
-	brcm_set_regulators(pcie, false);
+	brcm_set_regulators(pcie, TURN_OFF);
 
 	return ret;
 }
@@ -1210,7 +1254,7 @@ static int brcm_pcie_resume(struct device *dev)
 	int ret;
 
 	base = pcie->base;
-	brcm_set_regulators(pcie, true);
+	brcm_set_regulators(pcie, TURN_ON);
 	clk_prepare_enable(pcie->clk);
 
 	ret = brcm_phy_start(pcie);
@@ -1249,7 +1293,7 @@ static void __brcm_pcie_remove(struct brcm_pcie *pcie)
 	brcm_phy_stop(pcie);
 	reset_control_assert(pcie->rescal);
 	clk_disable_unprepare(pcie->clk);
-	brcm_set_regulators(pcie, false);
+	brcm_set_regulators(pcie, TURN_OFF_ALWAYS);
 }
 
 static int brcm_pcie_remove(struct platform_device *pdev)
@@ -1338,7 +1382,7 @@ static int brcm_pcie_probe(struct platform_device *pdev)
 		return ret;
 	}
 
-	brcm_set_regulators(pcie, true);
+	brcm_set_regulators(pcie, TURN_ON);
 	ret = brcm_pcie_setup(pcie);
 	if (ret)
 		goto fail;
-- 
2.17.1


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