PCI ASPM: cleanup __pcie_aspm_check_state_one

Clean up and simplify __pcie_aspm_check_state_one().

Acked-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

1 files changed, 25 insertions, 42 deletions

diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
index 68a4d4b15f9f..694ba5657758 100644
--- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c
@@ -370,56 +370,39 @@ static void pcie_aspm_cap_init(struct pcie_link_state *link, int blacklist)
         }
 }
 
-static unsigned int __pcie_aspm_check_state_one(struct pci_dev *pdev,
-        unsigned int state)
+/**
+ * __pcie_aspm_check_state_one - check latency for endpoint device.
+ * @endpoint: pointer to the struct pci_dev of endpoint device
+ *
+ * TBD: The latency from the endpoint to root complex vary per switch's
+ * upstream link state above the device. Here we just do a simple check
+ * which assumes all links above the device can be in L1 state, that
+ * is we just consider the worst case. If switch's upstream link can't
+ * be put into L0S/L1, then our check is too strictly.
+ */
+static u32 __pcie_aspm_check_state_one(struct pci_dev *endpoint, u32 state)
 {
-        struct pci_dev *parent_dev, *tmp_dev;
-        unsigned int l1_latency = 0;
-        struct pcie_link_state *link_state;
+        u32 l1_switch_latency = 0;
         struct aspm_latency *acceptable;
+        struct pcie_link_state *link;
 
-        parent_dev = pdev->bus->self;
-        link_state = parent_dev->link_state;
-        state &= link_state->aspm_support;
-        if (state == 0)
-                return 0;
-        acceptable = &link_state->acceptable[PCI_FUNC(pdev->devfn)];
+        link = endpoint->bus->self->link_state;
+        state &= link->aspm_support;
+        acceptable = &link->acceptable[PCI_FUNC(endpoint->devfn)];
 
-        /*
-         * Check latency for endpoint device.
-         * TBD: The latency from the endpoint to root complex vary per
-         * switch's upstream link state above the device. Here we just do a
-         * simple check which assumes all links above the device can be in L1
-         * state, that is we just consider the worst case. If switch's upstream
-         * link can't be put into L0S/L1, then our check is too strictly.
-         */
-        tmp_dev = pdev;
-        while (state & (PCIE_LINK_STATE_L0S | PCIE_LINK_STATE_L1)) {
-                parent_dev = tmp_dev->bus->self;
-                link_state = parent_dev->link_state;
+        while (link && state) {
                 if ((state & PCIE_LINK_STATE_L0S) &&
-                    (link_state->latency.l0s > acceptable->l0s))
+                    (link->latency.l0s > acceptable->l0s))
                         state &= ~PCIE_LINK_STATE_L0S;
-
                 if ((state & PCIE_LINK_STATE_L1) &&
-                    (link_state->latency.l1 + l1_latency > acceptable->l1))
+                    (link->latency.l1 + l1_switch_latency > acceptable->l1))
                         state &= ~PCIE_LINK_STATE_L1;
-
-                if (!parent_dev->bus->self) /* parent_dev is a root port */
-                        break;
-                else {
-                        /*
-                         * parent_dev is the downstream port of a switch, make
-                         * tmp_dev the upstream port of the switch
-                         */
-                        tmp_dev = parent_dev->bus->self;
-                        /*
-                         * every switch on the path to root complex need 1 more
-                         * microsecond for L1. Spec doesn't mention L0S.
-                         */
-                        if (state & PCIE_LINK_STATE_L1)
-                                l1_latency += 1000;
-                }
+                link = link->parent;
+                /*
+                 * Every switch on the path to root complex need 1
+                 * more microsecond for L1. Spec doesn't mention L0s.
+                 */
+                l1_switch_latency += 1000;
         }
         return state;
 }