linux-kernel - [RFC PATCH v1 1/4] [PCI/ASPM:] Remove struct pcie_link_state.clkpm

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Date:   Wed, 29 Sep 2021 02:43:57 +0200
From:   "Saheed O. Bolarinwa" <refactormyself@...il.com>
To:     helgaas@...nel.org
Cc:     "Bolarinwa O. Saheed" <refactormyself@...il.com>,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [RFC PATCH v1 1/4] [PCI/ASPM:] Remove struct pcie_link_state.clkpm_default

From: "Bolarinwa O. Saheed" <refactormyself@...il.com>

The clkpm_default member of the struct pcie_link_state stores the
value of the default clkpm state as it is in the BIOS.

This patch:
- Removes clkpm_default from struct pcie_link_state
- Creates pcie_get_clkpm_state() which return the clkpm state
  obtained the BIOS
- Replaces references to clkpm_default with call to
  pcie_get_clkpm_state()

Signed-off-by: Bolarinwa O. Saheed <refactormyself@...il.com>
---
 drivers/pci/pcie/aspm.c | 37 +++++++++++++++++++++++++++----------
 1 file changed, 27 insertions(+), 10 deletions(-)

diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
index 013a47f587ce..c23da9a4e2fb 100644
--- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c
@@ -63,7 +63,6 @@ struct pcie_link_state {
 	/* Clock PM state */
 	u32 clkpm_capable:1;		/* Clock PM capable? */
 	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 */
 
 	/* Exit latencies */
@@ -123,6 +122,30 @@ static int policy_to_aspm_state(struct pcie_link_state *link)
 	return 0;
 }
 
+static int pcie_get_clkpm_state(struct pci_dev *pdev)
+{
+	int enabled = 1;
+	u32 reg32;
+	u16 reg16;
+	struct pci_dev *child;
+	struct pci_bus *linkbus = pdev->subordinate;
+
+	/* All functions should have the same clkpm 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;
+	}
+
+	return enabled;
+}
+
 static int policy_to_clkpm_state(struct pcie_link_state *link)
 {
 	switch (aspm_policy) {
@@ -134,7 +157,7 @@ static int policy_to_clkpm_state(struct pcie_link_state *link)
 		/* Enable Clock PM */
 		return 1;
 	case POLICY_DEFAULT:
-		return link->clkpm_default;
+		return pcie_get_clkpm_state(link->pdev);
 	}
 	return 0;
 }
@@ -168,9 +191,8 @@ static void pcie_set_clkpm(struct pcie_link_state *link, int enable)
 
 static void pcie_clkpm_cap_init(struct pcie_link_state *link, int blacklist)
 {
-	int capable = 1, enabled = 1;
+	int capable = 1;
 	u32 reg32;
-	u16 reg16;
 	struct pci_dev *child;
 	struct pci_bus *linkbus = link->pdev->subordinate;
 
@@ -179,15 +201,10 @@ static void pcie_clkpm_cap_init(struct pcie_link_state *link, int blacklist)
 		pcie_capability_read_dword(child, PCI_EXP_LNKCAP, &reg32);
 		if (!(reg32 & PCI_EXP_LNKCAP_CLKPM)) {
 			capable = 0;
-			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_enabled = pcie_get_clkpm_state(link->pdev);
 	link->clkpm_capable = capable;
 	link->clkpm_disable = blacklist ? 1 : 0;
 }
-- 
2.20.1