linux-kernel - [RFC PATCH v2 3/3] PCI/ASPM: Remove struct pcie_link_state.clkpm

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Message-Id: <20211106175546.27785-4-refactormyself@gmail.com>
Date:   Sat,  6 Nov 2021 18:55:46 +0100
From:   "Saheed O. Bolarinwa" <refactormyself@...il.com>
To:     helgaas@...nel.org
Cc:     "Saheed O. Bolarinwa" <refactormyself@...il.com>,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [RFC PATCH v2 3/3] PCI/ASPM: Remove struct pcie_link_state.clkpm_enabled

The clkpm_enabled member of the struct pcie_link_state stores the
current Clock PM state for the device. However, when the state changes
it is persisted and thus can be retieved directly.

   - move calculations into pcie_clkpm_enabled()
   - removes clkpm_enabled from the struct pcie_link_state
   - removes all instance where clkpm_enable is set
   - replaces references to clkpm_enabled with a call to
     pcie_get_clkpm_state()

Signed-off-by: Saheed O. Bolarinwa <refactormyself@...il.com>
---
 drivers/pci/pcie/aspm.c | 43 +++++++++++++++++------------------------
 1 file changed, 18 insertions(+), 25 deletions(-)

diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
index c1f8f10b7a4c..9425d1e38c51 100644
--- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c
@@ -61,7 +61,6 @@ struct pcie_link_state {
 	u32 aspm_disable:7;		/* Disabled ASPM state */
 
 	/* Clock PM state */
-	u32 clkpm_enabled:1;		/* Current Clock PM state */
 	u32 clkpm_default:1;		/* Default Clock PM state by BIOS */
 	u32 clkpm_disable:1;		/* Clock PM disabled */
 
@@ -104,6 +103,21 @@ static const char *policy_str[] = {
 
 #define LINK_RETRAIN_TIMEOUT HZ
 
+static int pcie_clkpm_enabled(struct pci_dev *pdev)
+{
+	struct pci_dev *child;
+	struct pci_bus *linkbus = pdev->subordinate;
+	u16 ctl;
+
+	/* CLKREQ_EN is only applicable for Upstream Ports */
+	list_for_each_entry(child, &linkbus->devices, bus_list) {
+		pcie_capability_read_word(child, PCI_EXP_LNKCTL, &ctl);
+		if (!(ctl & PCI_EXP_LNKCTL_CLKREQ_EN))
+			return 0;
+	}
+	return 1;
+}
+
 static int pcie_clkpm_capable(struct pci_dev *pdev)
 {
 	u32 cap;
@@ -165,7 +179,7 @@ static void pcie_set_clkpm(struct pcie_link_state *link, int enable)
 	if (!pcie_clkpm_capable(link->pdev) || link->clkpm_disable)
 		enable = 0;
 	/* Need nothing if the specified equals to current state */
-	if (link->clkpm_enabled == enable)
+	if (pcie_clkpm_enabled(link->pdev) == enable)
 		return;
 
 	val = enable ? PCI_EXP_LNKCTL_CLKREQ_EN : 0;
@@ -173,31 +187,11 @@ static void pcie_set_clkpm(struct pcie_link_state *link, int enable)
 		pcie_capability_clear_and_set_word(child, PCI_EXP_LNKCTL,
 						   PCI_EXP_LNKCTL_CLKREQ_EN,
 						   val);
-
-	link->clkpm_enabled = !!enable;
 }
 
 static void pcie_clkpm_cap_init(struct pcie_link_state *link, int blacklist)
 {
-	int enabled = 1;
-	u32 reg32;
-	u16 reg16;
-	struct pci_dev *child;
-	struct pci_bus *linkbus = link->pdev->subordinate;
-
-	/* All functions should have the same cap and state, take the worst */
-	list_for_each_entry(child, &linkbus->devices, bus_list) {
-		pcie_capability_read_dword(child, PCI_EXP_LNKCAP, &reg32);
-		if (!(reg32 & PCI_EXP_LNKCAP_CLKPM)) {
-			enabled = 0;
-			break;
-		}
-		pcie_capability_read_word(child, PCI_EXP_LNKCTL, &reg16);
-		if (!(reg16 & PCI_EXP_LNKCTL_CLKREQ_EN))
-			enabled = 0;
-	}
-	link->clkpm_enabled = enabled;
-	link->clkpm_default = enabled;
+	link->clkpm_default = pcie_clkpm_enabled(link->pdev);
 	link->clkpm_disable = blacklist ? 1 : 0;
 }
 
@@ -1272,9 +1266,8 @@ static ssize_t clkpm_show(struct device *dev,
 			  struct device_attribute *attr, char *buf)
 {
 	struct pci_dev *pdev = to_pci_dev(dev);
-	struct pcie_link_state *link = pcie_aspm_get_link(pdev);
 
-	return sysfs_emit(buf, "%d\n", link->clkpm_enabled);
+	return sysfs_emit(buf, "%d\n", pcie_clkpm_enabled(pdev));
 }
 
 static ssize_t clkpm_store(struct device *dev,
-- 
2.20.1