[PATCH v3 2/2] irqchip: dw-apb-ictl: add irq_set_affinity support
From: Jisheng Zhang
Date: Mon Jul 06 2015 - 00:17:10 EST
On Marvell Berlin SoCs, the cpu's local timer is shutdown when the cpu
goes to a deep idle state, then the timer framework will be notified to
use a broadcast timer instead. In our case, the broadcast timer uses
dw-apb-ictl as interrupt chip. This patch adds irq_set_affinity support
so that the going to deep idle state cpu can set the interrupt affinity
of the broadcast interrupt to avoid unnecessary wakeups and IPIs.
NOTE: We achieved this by changing the parent interrupt affinity of a
chained interrupt, so it migrates every interrupt on the child interrupt
controller which isn't a good thing to do as pointed out by Russell
King. Thomas pointed out "we should at least make that an opt-in behaviour
and not enabled by default", this patch adds a device tree option for
this purpose. If "migrates every interrupt on the child interrupt controller"
doesn't matter, turning on the option would add irq_set_affinity
support which might be useful in some cases (EG: can save reduce power
consumption on Marvell Berlin SoCs).
A simple test:
~ # rm /tmp/test.sh
~ # cat > /tmp/test.sh
cat /proc/interrupts
for i in `seq 10` ; do sleep $i; done
cat /proc/interrupts
~ # chmod +x /tmp/test.sh
~ # taskset 0x2 /tmp/test.sh
without the patch:
CPU0 CPU1
27: 115 36 GIC 27 arch_timer
45: 62 0 GIC 45 mmc0
160: 88 0 interrupt-controller 8 timer
227: 0 0 interrupt-controller 4 f7e81400.i2c
228: 0 0 interrupt-controller 5 f7e81800.i2c
229: 0 0 interrupt-controller 7 dw_spi65535
230: 0 0 interrupt-controller 21 f7e84000.i2c
231: 0 0 interrupt-controller 20 f7e84800.i2c
265: 445 0 interrupt-controller 8 serial
IPI0: 0 0 CPU wakeup interrupts
IPI1: 0 11 Timer broadcast interrupts
IPI2: 56 104 Rescheduling interrupts
IPI3: 0 0 Function call interrupts
IPI4: 0 4 Single function call interrupts
IPI5: 0 0 CPU stop interrupts
IPI6: 25 27 IRQ work interrupts
IPI7: 0 0 completion interrupts
IPI8: 0 0 CPU backtrace
Err: 0
CPU0 CPU1
27: 115 38 GIC 27 arch_timer
45: 62 0 GIC 45 mmc0
160: 160 0 interrupt-controller 8 timer
227: 0 0 interrupt-controller 4 f7e81400.i2c
228: 0 0 interrupt-controller 5 f7e81800.i2c
229: 0 0 interrupt-controller 7 dw_spi65535
230: 0 0 interrupt-controller 21 f7e84000.i2c
231: 0 0 interrupt-controller 20 f7e84800.i2c
265: 514 0 interrupt-controller 8 serial
IPI0: 0 0 CPU wakeup interrupts
IPI1: 0 83 Timer broadcast interrupts
IPI2: 56 104 Rescheduling interrupts
IPI3: 0 0 Function call interrupts
IPI4: 0 4 Single function call interrupts
IPI5: 0 0 CPU stop interrupts
IPI6: 25 46 IRQ work interrupts
IPI7: 0 0 completion interrupts
IPI8: 0 0 CPU backtrace
Err: 0
cpu0 get 160-88=72 timer interrupts, CPU1 got 83-11=72 broadcast timer
IPIs. So, overall system got 72+72=144 wake ups and 72 broadcast timer IPIs
With the patch:
CPU0 CPU1
27: 107 37 GIC 27 arch_timer
45: 62 0 GIC 45 mmc0
160: 66 7 interrupt-controller 8 timer
227: 0 0 interrupt-controller 4 f7e81400.i2c
228: 0 0 interrupt-controller 5 f7e81800.i2c
229: 0 0 interrupt-controller 7 dw_spi65535
230: 0 0 interrupt-controller 21 f7e84000.i2c
231: 0 0 interrupt-controller 20 f7e84800.i2c
265: 311 0 interrupt-controller 8 serial
IPI0: 0 0 CPU wakeup interrupts
IPI1: 2 4 Timer broadcast interrupts
IPI2: 58 100 Rescheduling interrupts
IPI3: 0 0 Function call interrupts
IPI4: 0 4 Single function call interrupts
IPI5: 0 0 CPU stop interrupts
IPI6: 21 24 IRQ work interrupts
IPI7: 0 0 completion interrupts
IPI8: 0 0 CPU backtrace
Err: 0
CPU0 CPU1
27: 107 39 GIC 27 arch_timer
45: 62 0 GIC 45 mmc0
160: 69 75 interrupt-controller 8 timer
227: 0 0 interrupt-controller 4 f7e81400.i2c
228: 0 0 interrupt-controller 5 f7e81800.i2c
229: 0 0 interrupt-controller 7 dw_spi65535
230: 0 0 interrupt-controller 21 f7e84000.i2c
231: 0 0 interrupt-controller 20 f7e84800.i2c
265: 380 0 interrupt-controller 8 serial
IPI0: 0 0 CPU wakeup interrupts
IPI1: 3 6 Timer broadcast interrupts
IPI2: 60 100 Rescheduling interrupts
IPI3: 0 0 Function call interrupts
IPI4: 0 4 Single function call interrupts
IPI5: 0 0 CPU stop interrupts
IPI6: 21 45 IRQ work interrupts
IPI7: 0 0 completion interrupts
IPI8: 0 0 CPU backtrace
Err: 0
cpu0 got 69-66=3, cpu1 got 75-7=68 timer interrupts. cpu0 got 3-2=1
broadcast timer IPIs, cpu1 got 6-4=2 broadcast timer IPIs. So, overall
system got 3+68+1+2=74 wakeups and 1+2=3 broadcast timer IPIs.
This patch removes 50% wakeups and almost 100% broadcast timer IPIs!
Signed-off-by: Jisheng Zhang <jszhang@xxxxxxxxxxx>
---
.../interrupt-controller/snps,dw-apb-ictl.txt | 5 +++++
drivers/irqchip/irq-dw-apb-ictl.c | 25 ++++++++++++++++++++++
2 files changed, 30 insertions(+)
diff --git a/Documentation/devicetree/bindings/interrupt-controller/snps,dw-apb-ictl.txt b/Documentation/devicetree/bindings/interrupt-controller/snps,dw-apb-ictl.txt
index 4929117..1dd1786 100644
--- a/Documentation/devicetree/bindings/interrupt-controller/snps,dw-apb-ictl.txt
+++ b/Documentation/devicetree/bindings/interrupt-controller/snps,dw-apb-ictl.txt
@@ -13,6 +13,11 @@ Required properties:
- interrupts: interrupt reference to primary interrupt controller
- interrupt-parent: (optional) reference specific primary interrupt controller
+Optional properties:
+- irq-set-affinity: If present, the ictl will be assumed to be able to set
+ the affinity of every interrupt on the ictl to the same one by changing the
+ parent interrupt affinity.
+
The interrupt sources map to the corresponding bits in the interrupt
registers, i.e.
- 0 maps to bit 0 of low interrupts,
diff --git a/drivers/irqchip/irq-dw-apb-ictl.c b/drivers/irqchip/irq-dw-apb-ictl.c
index 8bef7f7..4be88cb 100644
--- a/drivers/irqchip/irq-dw-apb-ictl.c
+++ b/drivers/irqchip/irq-dw-apb-ictl.c
@@ -29,6 +29,7 @@
struct dw_apb_ictl_priv {
struct irq_domain *domain;
+ unsigned int parent_irq;
};
static void dw_apb_ictl_handler(unsigned int irq, struct irq_desc *desc)
@@ -56,6 +57,21 @@ static void dw_apb_ictl_handler(unsigned int irq, struct irq_desc *desc)
chained_irq_exit(chip, desc);
}
+static int dw_apb_ictl_set_affinity(struct irq_data *d,
+ const struct cpumask *mask_val,
+ bool force)
+{
+ struct irq_chip_generic *gc = irq_data_get_irq_chip_data(d);
+ struct dw_apb_ictl_priv *priv = gc->private;
+ struct irq_chip *chip = irq_get_chip(priv->parent_irq);
+ struct irq_data *data = irq_get_irq_data(priv->parent_irq);
+
+ if (chip && chip->irq_set_affinity)
+ return chip->irq_set_affinity(data, mask_val, force);
+ else
+ return -EINVAL;
+}
+
#ifdef CONFIG_PM
static void dw_apb_ictl_resume(struct irq_data *d)
{
@@ -82,6 +98,7 @@ static int __init dw_apb_ictl_init(struct device_node *np,
void __iomem *iobase;
int ret, nrirqs, irq;
u32 reg;
+ bool can_set_affinity = of_property_read_bool(np, "irq-set-affinity");
priv = kzalloc(sizeof(*priv), GFP_KERNEL);
if (!priv)
@@ -95,6 +112,8 @@ static int __init dw_apb_ictl_init(struct device_node *np,
goto err_free;
}
+ priv->parent_irq = irq;
+
ret = of_address_to_resource(np, 0, &r);
if (ret) {
pr_err("%s: unable to get resource\n", np->full_name);
@@ -160,6 +179,9 @@ static int __init dw_apb_ictl_init(struct device_node *np,
gc->chip_types[0].chip.irq_mask = irq_gc_mask_set_bit;
gc->chip_types[0].chip.irq_unmask = irq_gc_mask_clr_bit;
gc->chip_types[0].chip.irq_resume = dw_apb_ictl_resume;
+ if (can_set_affinity)
+ gc->chip_types[0].chip.irq_set_affinity =
+ dw_apb_ictl_set_affinity;
if (nrirqs > 32) {
gc->chip_types[1].regs.mask = APB_INT_MASK_H;
@@ -167,6 +189,9 @@ static int __init dw_apb_ictl_init(struct device_node *np,
gc->chip_types[1].chip.irq_mask = irq_gc_mask_set_bit;
gc->chip_types[1].chip.irq_unmask = irq_gc_mask_clr_bit;
gc->chip_types[1].chip.irq_resume = dw_apb_ictl_resume;
+ if (can_set_affinity)
+ gc->chip_types[1].chip.irq_set_affinity =
+ dw_apb_ictl_set_affinity;
}
irq_set_handler_data(irq, gc);
--
2.1.4
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