iwlwifi: configure the LTR

The LTR is the handshake between the device and the root
complex about the latency allowed when the bus exits power
save. This configuration was missing and this led to high
latency in the link power up. The end user could experience
high latency in the network because of this.

Cc: <stable@vger.kernel.org> [3.10+]
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>

1 files changed, 9 insertions, 7 deletions

diff --git a/drivers/net/wireless/iwlwifi/pcie/trans.c b/drivers/net/wireless/iwlwifi/pcie/trans.c
index 1393bac0025c..c706dba67cdd 100644
--- a/drivers/net/wireless/iwlwifi/pcie/trans.c
+++ b/drivers/net/wireless/iwlwifi/pcie/trans.c
@@ -174,6 +174,7 @@ static void iwl_pcie_apm_config(struct iwl_trans *trans)
 {
         struct iwl_trans_pcie *trans_pcie = IWL_TRANS_GET_PCIE_TRANS(trans);
         u16 lctl;
+        u16 cap;
 
         /*
          * HW bug W/A for instability in PCIe bus L0S->L1 transition.
@@ -184,16 +185,17 @@ static void iwl_pcie_apm_config(struct iwl_trans *trans)
          *    power savings, even without L1.
          */
         pcie_capability_read_word(trans_pcie->pci_dev, PCI_EXP_LNKCTL, &lctl);
-        if (lctl & PCI_EXP_LNKCTL_ASPM_L1) {
-                /* L1-ASPM enabled; disable(!) L0S */
+        if (lctl & PCI_EXP_LNKCTL_ASPM_L1)
                 iwl_set_bit(trans, CSR_GIO_REG, CSR_GIO_REG_VAL_L0S_ENABLED);
-                dev_info(trans->dev, "L1 Enabled; Disabling L0S\n");
-        } else {
-                /* L1-ASPM disabled; enable(!) L0S */
+        else
                 iwl_clear_bit(trans, CSR_GIO_REG, CSR_GIO_REG_VAL_L0S_ENABLED);
-                dev_info(trans->dev, "L1 Disabled; Enabling L0S\n");
-        }
         trans->pm_support = !(lctl & PCI_EXP_LNKCTL_ASPM_L0S);
+
+        pcie_capability_read_word(trans_pcie->pci_dev, PCI_EXP_DEVCTL2, &cap);
+        trans->ltr_enabled = cap & PCI_EXP_DEVCTL2_LTR_EN;
+        dev_info(trans->dev, "L1 %sabled - LTR %sabled\n",
+                 (lctl & PCI_EXP_LNKCTL_ASPM_L1) ? "En" : "Dis",
+                 trans->ltr_enabled ? "En" : "Dis");
 }
 
 /*