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Subject[PATCH 07/16] thunderbolt: Configure interrupt throttling for all interrupts
Date
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>
---
drivers/thunderbolt/nhi.c | 22 +++++++++++++++++++---
drivers/thunderbolt/nhi_regs.h | 2 ++
2 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/drivers/thunderbolt/nhi.c b/drivers/thunderbolt/nhi.c
index 05af126a2435..bc44cbaaf05a 100644
--- a/drivers/thunderbolt/nhi.c
+++ b/drivers/thunderbolt/nhi.c
@@ -651,6 +651,21 @@ static int nhi_suspend_noirq(struct device *dev)
return tb_domain_suspend_noirq(tb);
}

+static void nhi_enable_int_throttling(struct tb_nhi *nhi)
+{
+ 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 +678,8 @@ 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 +734,8 @@ 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 +815,6 @@ 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
--
2.13.5
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