PCI ASPM: cleanup calc_Lx_latency
Kenji Kaneshige [Wed, 13 May 2009 03:21:48 +0000 (12:21 +0900)]
Cleanup for calc_L0S_latency() and calc_L1_latency().

  - Separate exit latency and acceptable latency calculation.
  - Some minor cleanups.

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>

drivers/pci/pcie/aspm.c

index d85f77f..23fabb3 100644 (file)
@@ -257,38 +257,36 @@ static void pcie_aspm_configure_common_clock(struct pcie_link_state *link)
        pci_write_config_word(parent, ppos + PCI_EXP_LNKCTL, parent_reg);
 }
 
-/*
- * calc_L0S_latency: Convert L0s latency encoding to ns
- */
-static unsigned int calc_L0S_latency(unsigned int latency_encoding, int ac)
+/* Convert L0s latency encoding to ns */
+static u32 calc_l0s_latency(u32 encoding)
 {
-       unsigned int ns = 64;
+       if (encoding == 0x7)
+               return (5 * 1000);      /* > 4us */
+       return (64 << encoding);
+}
 
-       if (latency_encoding == 0x7) {
-               if (ac)
-                       ns = -1U;
-               else
-                       ns = 5*1000; /* > 4us */
-       } else
-               ns *= (1 << latency_encoding);
-       return ns;
+/* Convert L0s acceptable latency encoding to ns */
+static u32 calc_l0s_acceptable(u32 encoding)
+{
+       if (encoding == 0x7)
+               return -1U;
+       return (64 << encoding);
 }
 
-/*
- * calc_L1_latency: Convert L1 latency encoding to ns
- */
-static unsigned int calc_L1_latency(unsigned int latency_encoding, int ac)
+/* Convert L1 latency encoding to ns */
+static u32 calc_l1_latency(u32 encoding)
 {
-       unsigned int ns = 1000;
+       if (encoding == 0x7)
+               return (65 * 1000);     /* > 64us */
+       return (1000 << encoding);
+}
 
-       if (latency_encoding == 0x7) {
-               if (ac)
-                       ns = -1U;
-               else
-                       ns = 65*1000; /* > 64us */
-       } else
-               ns *= (1 << latency_encoding);
-       return ns;
+/* Convert L1 acceptable latency encoding to ns */
+static u32 calc_l1_acceptable(u32 encoding)
+{
+       if (encoding == 0x7)
+               return -1U;
+       return (1000 << encoding);
 }
 
 static void pcie_aspm_get_cap_device(struct pci_dev *pdev, u32 *state,
@@ -296,7 +294,7 @@ static void pcie_aspm_get_cap_device(struct pci_dev *pdev, u32 *state,
 {
        int pos;
        u16 reg16;
-       u32 reg32, latency;
+       u32 reg32, encoding;
 
        *l0s = *l1 = *enabled = 0;
        pos = pci_find_capability(pdev, PCI_CAP_ID_EXP);
@@ -308,11 +306,11 @@ static void pcie_aspm_get_cap_device(struct pci_dev *pdev, u32 *state,
        if (*state == 0)
                return;
 
-       latency = (reg32 & PCI_EXP_LNKCAP_L0SEL) >> 12;
-       *l0s = calc_L0S_latency(latency, 0);
+       encoding = (reg32 & PCI_EXP_LNKCAP_L0SEL) >> 12;
+       *l0s = calc_l0s_latency(encoding);
        if (*state & PCIE_LINK_STATE_L1) {
-               latency = (reg32 & PCI_EXP_LNKCAP_L1EL) >> 15;
-               *l1 = calc_L1_latency(latency, 0);
+               encoding = (reg32 & PCI_EXP_LNKCAP_L1EL) >> 15;
+               *l1 = calc_l1_latency(encoding);
        }
        pci_read_config_word(pdev, pos + PCI_EXP_LNKCTL, &reg16);
        *enabled = reg16 & (PCIE_LINK_STATE_L0S | PCIE_LINK_STATE_L1);
@@ -358,8 +356,7 @@ static void pcie_aspm_cap_init(struct pcie_link_state *link, int blacklist)
        /* ENDPOINT states*/
        list_for_each_entry(child, &linkbus->devices, bus_list) {
                int pos;
-               u32 reg32;
-               unsigned int latency;
+               u32 reg32, encoding;
                struct aspm_latency *acceptable =
                        &link->acceptable[PCI_FUNC(child->devfn)];
 
@@ -369,13 +366,11 @@ static void pcie_aspm_cap_init(struct pcie_link_state *link, int blacklist)
 
                pos = pci_find_capability(child, PCI_CAP_ID_EXP);
                pci_read_config_dword(child, pos + PCI_EXP_DEVCAP, &reg32);
-               latency = (reg32 & PCI_EXP_DEVCAP_L0S) >> 6;
-               latency = calc_L0S_latency(latency, 1);
-               acceptable->l0s = latency;
+               encoding = (reg32 & PCI_EXP_DEVCAP_L0S) >> 6;
+               acceptable->l0s = calc_l0s_acceptable(encoding);
                if (link->aspm_support & PCIE_LINK_STATE_L1) {
-                       latency = (reg32 & PCI_EXP_DEVCAP_L1) >> 9;
-                       latency = calc_L1_latency(latency, 1);
-                       acceptable->l1 = latency;
+                       encoding = (reg32 & PCI_EXP_DEVCAP_L1) >> 9;
+                       acceptable->l1 = calc_l1_acceptable(encoding);
                }
        }
 }