tg3: Fix single-vector MSI-X code

Kdump kernels leave MSI-X interrupts (as setup by the crashed kernel)
enabled.  However, kdump only enables one CPU in the new environment,
thus causing tg3 to abort MSI-X setup.  When the driver attempts to
enable INTA or MSI interrupt modes on a kdump kernel, interrupt
delivery fails.

This patch attempts to workaround the problem by forcing the driver
to enable a single MSI-X interrupt.  In such a configuration, the
device's multivector interrupt mode must be disabled.

Signed-off-by: Matt Carlson <mcarlson@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 14 insertions, 13 deletions

diff --git a/drivers/net/ethernet/broadcom/tg3.c b/drivers/net/ethernet/broadcom/tg3.c
index 076e02a415a0..d529af99157d 100644
--- a/drivers/net/ethernet/broadcom/tg3.c
+++ b/drivers/net/ethernet/broadcom/tg3.c
@@ -8846,9 +8846,11 @@ static int tg3_reset_hw(struct tg3 *tp, int reset_phy)
         tw32_f(GRC_LOCAL_CTRL, tp->grc_local_ctrl);
         udelay(100);
 
-        if (tg3_flag(tp, USING_MSIX) && tp->irq_cnt > 1) {
+        if (tg3_flag(tp, USING_MSIX)) {
                 val = tr32(MSGINT_MODE);
-                val |= MSGINT_MODE_MULTIVEC_EN | MSGINT_MODE_ENABLE;
+                val |= MSGINT_MODE_ENABLE;
+                if (tp->irq_cnt > 1)
+                        val |= MSGINT_MODE_MULTIVEC_EN;
                 if (!tg3_flag(tp, 1SHOT_MSI))
                         val |= MSGINT_MODE_ONE_SHOT_DISABLE;
                 tw32(MSGINT_MODE, val);
@@ -9548,19 +9550,18 @@ static int tg3_request_firmware(struct tg3 *tp)
 
 static bool tg3_enable_msix(struct tg3 *tp)
 {
-        int i, rc, cpus = num_online_cpus();
+        int i, rc;
         struct msix_entry msix_ent[tp->irq_max];
 
-        if (cpus == 1)
-                /* Just fallback to the simpler MSI mode. */
-                return false;
-
-        /*
-         * We want as many rx rings enabled as there are cpus.
-         * The first MSIX vector only deals with link interrupts, etc,
-         * so we add one to the number of vectors we are requesting.
-         */
-        tp->irq_cnt = min_t(unsigned, cpus + 1, tp->irq_max);
+        tp->irq_cnt = num_online_cpus();
+        if (tp->irq_cnt > 1) {
+                /* We want as many rx rings enabled as there are cpus.
+                 * In multiqueue MSI-X mode, the first MSI-X vector
+                 * only deals with link interrupts, etc, so we add
+                 * one to the number of vectors we are requesting.
+                 */
+                tp->irq_cnt = min_t(unsigned, tp->irq_cnt + 1, tp->irq_max);
+        }
 
         for (i = 0; i < tp->irq_max; i++) {
                 msix_ent[i].entry  = i;