thunderbolt: Configure interrupt throttling for all interrupts

This will keep the interrupt delivery rate reasonable. The value used
here (128 us) is a recommendation from the hardware people.

This code is based on the work done by Amir Levy and Michael Jamet.

Signed-off-by: Michael Jamet <michael.jamet@intel.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Yehezkel Bernat <yehezkel.bernat@intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 22 insertions, 3 deletions

diff --git a/drivers/thunderbolt/nhi.c b/drivers/thunderbolt/nhi.c
index 05af126a2435..8a7a3d0133f9 100644
--- a/drivers/thunderbolt/nhi.c
+++ b/drivers/thunderbolt/nhi.c
@@ -651,6 +651,22 @@ static int nhi_suspend_noirq(struct device *dev)
         return tb_domain_suspend_noirq(tb);
 }
 
+static void nhi_enable_int_throttling(struct tb_nhi *nhi)
+{
+        /* Throttling is specified in 256ns increments */
+        u32 throttle = DIV_ROUND_UP(128 * NSEC_PER_USEC, 256);
+        unsigned int i;
+
+        /*
+         * Configure interrupt throttling for all vectors even if we
+         * only use few.
+         */
+        for (i = 0; i < MSIX_MAX_VECS; i++) {
+                u32 reg = REG_INT_THROTTLING_RATE + i * 4;
+                iowrite32(throttle, nhi->iobase + reg);
+        }
+}
+
 static int nhi_resume_noirq(struct device *dev)
 {
         struct pci_dev *pdev = to_pci_dev(dev);
@@ -663,6 +679,8 @@ static int nhi_resume_noirq(struct device *dev)
          */
         if (!pci_device_is_present(pdev))
                 tb->nhi->going_away = true;
+        else
+                nhi_enable_int_throttling(tb->nhi);
 
         return tb_domain_resume_noirq(tb);
 }
@@ -717,6 +735,8 @@ static int nhi_init_msi(struct tb_nhi *nhi)
         /* In case someone left them on. */
         nhi_disable_interrupts(nhi);
 
+        nhi_enable_int_throttling(nhi);
+
         ida_init(&nhi->msix_ida);
 
         /*
@@ -796,9 +816,6 @@ static int nhi_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 
         pci_set_master(pdev);
 
-        /* magic value - clock related? */
-        iowrite32(3906250 / 10000, nhi->iobase + 0x38c00);
-
         tb = icm_probe(nhi);
         if (!tb)
                 tb = tb_probe(nhi);
diff --git a/drivers/thunderbolt/nhi_regs.h b/drivers/thunderbolt/nhi_regs.h
index 09ed574e92ff..46eff69b19ad 100644
--- a/drivers/thunderbolt/nhi_regs.h
+++ b/drivers/thunderbolt/nhi_regs.h
@@ -95,6 +95,8 @@ struct ring_desc {
 #define REG_RING_INTERRUPT_BASE 0x38200
 #define RING_INTERRUPT_REG_COUNT(nhi) ((31 + 2 * nhi->hop_count) / 32)
 
+#define REG_INT_THROTTLING_RATE 0x38c00
+
 /* Interrupt Vector Allocation */
 #define REG_INT_VEC_ALLOC_BASE  0x38c40
 #define REG_INT_VEC_ALLOC_BITS  4