On Wed, 2013-06-26 at 07:02 +0800, Stephen Warren wrote:

On 06/25/2013 03:23 AM, Joseph Lo wrote:

quoted

There is a difference between GICv1 and v2 when CPU in power management
mode (aka CPU power down on Tegra). For GICv1, IRQ/FIQ interrupt lines
going to CPU are same lines which are also used for wake-interrupt.
Therefore, we cannot disable the GIC CPU interface if we need to use same
interrupts for CPU wake purpose. This creates a race condition for CPU
power off entry. Also, in GICv1, disabling GICv1 CPU interface puts GICv1
into bypass mode such that incoming legacy IRQ/FIQ are sent to CPU, which
means disabling GIC CPU interface doesn't really disable IRQ/FIQ to CPU.

GICv2 provides a wake IRQ/FIQ (for wake-event purpose), which are not
disabled by GIC CPU interface. This is done by adding a bypass override
capability when the interrupts are disabled at the CPU interface. To
support this, there are four bits about IRQ/FIQ BypassDisable in CPU
interface Control Register. When the IRQ/FIQ not being driver by the
CPU interface, each interrupt output signal can be deasserted rather
than being driven by the legacy interrupt input.

...

quoted

diff --git a/arch/arm/mach-tegra/irq.c b/arch/arm/mach-tegra/irq.c

quoted

+static int tegra_gic_notifier(struct notifier_block *self,
+			      unsigned long cmd, void *v)
+{
+	switch (cmd) {
+	case CPU_PM_ENTER:
+		writel_relaxed(0x1E0, tegra_gic_cpu_base + GIC_CPU_CTRL);

I assume that 0x1e0 is the "four bits" for IRQ/FIQ bypass disable that
are mentioned in the commit description. are there #defines that can be
used instead of literal 0x1e0 here?

The common "arm-gic.h" didn't have the new define for GICv2 yet. So I
didn't define something like GIC_CPU_{FIQ,IRQ}BypDisGrp{0,1} for Tegra.

Thanks,
Joseph