8c405cdccc
The patches were generated from the RPi repo with the following command: git format-patch v6.6.34..rpi-6.1.y Some patches needed rebasing and, as usual, the applied and reverted, wireless drivers, Github workflows, READMEs and defconfigs patches were removed. Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
115 lines
3.7 KiB
Diff
115 lines
3.7 KiB
Diff
From 273ee28efedfdfc546906da067581ba9d86edfc9 Mon Sep 17 00:00:00 2001
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From: Michael Zoran <mzoran@crowfest.net>
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Date: Sat, 14 Jan 2017 21:43:57 -0800
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Subject: [PATCH 0112/1085] ARM64: Round-Robin dispatch IRQs between CPUs.
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IRQ-CPU mapping is round robined on ARM64 to increase
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concurrency and allow multiple interrupts to be serviced
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at a time. This reduces the need for FIQ.
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Signed-off-by: Michael Zoran <mzoran@crowfest.net>
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drivers: irqchip: irq-bcm2835: Concurrency fix
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The commit shown in Fixes: aims to improve interrupt throughput by
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getting the handlers invoked on different CPU cores. It does so (*) by
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using an irq_ack hook to change the interrupt routing.
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Unfortunately, the IRQ status bits must be cleared at source, which only
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happens once the interrupt handler has run - there is no easy way for
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one core to claim one of the IRQs before sending the remainder to the
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next core on the list, so waking another core immediately results in a
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race with a chance of both cores handling the same IRQ. It is probably
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for this reason that the routing change is deferred to irq_ack, but that
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doesn't guarantee no clashes - after irq_ack is called, control returns
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to bcm2836_chained_handler_irq which proceeds to check for other pending
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IRQs at a time when the next core is probably doing the same thing.
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Since the whole point of the original commit is to distribute the IRQ
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handling, there is no reason to attempt to handle multiple IRQs in one
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interrupt callback, so the problem can be solved (or at least made much
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harder to reproduce) by changing a "while" into an "if", so that each
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invocation only handles one IRQ.
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(*) I'm not convinced it's as effective as claimed since irq_ack is
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called _after_ the interrupt handler, but the author thought it made a
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difference.
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See: https://github.com/raspberrypi/linux/issues/5214
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https://github.com/raspberrypi/linux/pull/1794
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Fixes: fd4c9785bde8 ("ARM64: Round-Robin dispatch IRQs between CPUs.")
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Signed-off-by: Phil Elwell <phil@raspberrypi.com>
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---
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drivers/irqchip/irq-bcm2835.c | 18 ++++++++++++++++--
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drivers/irqchip/irq-bcm2836.c | 21 +++++++++++++++++++++
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2 files changed, 37 insertions(+), 2 deletions(-)
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--- a/drivers/irqchip/irq-bcm2835.c
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+++ b/drivers/irqchip/irq-bcm2835.c
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@@ -154,10 +154,23 @@ static void armctrl_unmask_irq(struct ir
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}
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}
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+#ifdef CONFIG_ARM64
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+void bcm2836_arm_irqchip_spin_gpu_irq(void);
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+
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+static void armctrl_ack_irq(struct irq_data *d)
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+{
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+ bcm2836_arm_irqchip_spin_gpu_irq();
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+}
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+
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+#endif
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+
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static struct irq_chip armctrl_chip = {
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.name = "ARMCTRL-level",
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.irq_mask = armctrl_mask_irq,
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- .irq_unmask = armctrl_unmask_irq
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+ .irq_unmask = armctrl_unmask_irq,
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+#ifdef CONFIG_ARM64
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+ .irq_ack = armctrl_ack_irq
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+#endif
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};
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static int armctrl_xlate(struct irq_domain *d, struct device_node *ctrlr,
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@@ -330,7 +343,8 @@ static void bcm2836_chained_handle_irq(s
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{
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u32 hwirq;
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- while ((hwirq = get_next_armctrl_hwirq()) != ~0)
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+ hwirq = get_next_armctrl_hwirq();
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+ if (hwirq != ~0)
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generic_handle_domain_irq(intc.domain, hwirq);
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}
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--- a/drivers/irqchip/irq-bcm2836.c
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+++ b/drivers/irqchip/irq-bcm2836.c
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@@ -87,6 +87,27 @@ static void bcm2836_arm_irqchip_unmask_g
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{
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}
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+#ifdef CONFIG_ARM64
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+
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+void bcm2836_arm_irqchip_spin_gpu_irq(void)
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+{
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+ u32 i;
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+ void __iomem *gpurouting = (intc.base + LOCAL_GPU_ROUTING);
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+ u32 routing_val = readl(gpurouting);
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+
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+ for (i = 1; i <= 3; i++) {
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+ u32 new_routing_val = (routing_val + i) & 3;
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+
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+ if (cpu_active(new_routing_val)) {
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+ writel(new_routing_val, gpurouting);
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+ return;
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+ }
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+ }
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+}
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+EXPORT_SYMBOL(bcm2836_arm_irqchip_spin_gpu_irq);
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+
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+#endif
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+
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static struct irq_chip bcm2836_arm_irqchip_gpu = {
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.name = "bcm2836-gpu",
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.irq_mask = bcm2836_arm_irqchip_mask_gpu_irq,
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