e1000e: default IntMode based on kernel config & available hardware support

Based on a patch from Prabhakar Kushwaha <prabhakar@freescale.com>, set
appropriate default interrupt mode dependent on whether CONFIG_PCI_MSI
is enabled in the kernel configuration and if the hardware supports
MSI-X.  Set the module parameter log message accordingly.

Signed-off-by: Bruce Allan <bruce.w.allan@intel.com>
Cc: Jin Qing <b24347@freescale.com>
Cc: Prabhakar Kushwaha <prabhakar@freescale.com>
Cc: Jin Qing <b24347@freescale.com>
Cc: Kumar Gala <galak@kernel.crashing.org>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

diff --git a/drivers/net/ethernet/intel/e1000e/param.c b/drivers/net/ethernet/intel/e1000e/param.c
index 20e93b0..40664f5 100644 (file)
--- a/drivers/net/ethernet/intel/e1000e/param.c
+++ b/drivers/net/ethernet/intel/e1000e/param.c
@@ -113,11 +113,20 @@ E1000_PARAM(InterruptThrottleRate, "Interrupt Throttling Rate");
 #define MAX_ITR 100000
 #define MIN_ITR 100
 
-/* IntMode (Interrupt Mode)
+/*
+ * IntMode (Interrupt Mode)
+ *
+ * Valid Range: varies depending on kernel configuration & hardware support
+ *
+ * legacy=0, MSI=1, MSI-X=2
  *
- * Valid Range: 0 - 2
+ * When MSI/MSI-X support is enabled in kernel-
+ *   Default Value: 2 (MSI-X) when supported by hardware, 1 (MSI) otherwise
+ * When MSI/MSI-X support is not enabled in kernel-
+ *   Default Value: 0 (legacy)
  *
- * Default Value: 2 (MSI-X)
+ * When a mode is specified that is not allowed/supported, it will be
+ * demoted to the most advanced interrupt mode available.
  */
 E1000_PARAM(IntMode, "Interrupt Mode");
 #define MAX_INTMODE    2
@@ -388,12 +397,33 @@ void __devinit e1000e_check_options(struct e1000_adapter *adapter)
                static struct e1000_option opt = {
                        .type = range_option,
                        .name = "Interrupt Mode",
-                       .err  = "defaulting to 2 (MSI-X)",
-                       .def  = E1000E_INT_MODE_MSIX,
-                       .arg  = { .r = { .min = MIN_INTMODE,
-                                        .max = MAX_INTMODE } }
+#ifndef CONFIG_PCI_MSI
+                       .err  = "defaulting to 0 (legacy)",
+                       .def  = E1000E_INT_MODE_LEGACY,
+                       .arg  = { .r = { .min = 0,
+                                        .max = 0 } }
+#endif
                };
 
+#ifdef CONFIG_PCI_MSI
+               if (adapter->flags & FLAG_HAS_MSIX) {
+                       opt.err = kstrdup("defaulting to 2 (MSI-X)",
+                                         GFP_KERNEL);
+                       opt.def = E1000E_INT_MODE_MSIX;
+                       opt.arg.r.max = E1000E_INT_MODE_MSIX;
+               } else {
+                       opt.err = kstrdup("defaulting to 1 (MSI)", GFP_KERNEL);
+                       opt.def = E1000E_INT_MODE_MSI;
+                       opt.arg.r.max = E1000E_INT_MODE_MSI;
+               }
+
+               if (!opt.err) {
+                       dev_err(&adapter->pdev->dev,
+                               "Failed to allocate memory\n");
+                       return;
+               }
+#endif
+
                if (num_IntMode > bd) {
                        unsigned int int_mode = IntMode[bd];
                        e1000_validate_option(&int_mode, &opt, adapter);
@@ -401,6 +431,10 @@ void __devinit e1000e_check_options(struct e1000_adapter *adapter)
                } else {
                        adapter->int_mode = opt.def;
                }
+
+#ifdef CONFIG_PCI_MSI
+               kfree(opt.err);
+#endif
        }
        { /* Smart Power Down */
                static const struct e1000_option opt = {