On 02/16/2015 05:54 AM, Jan Kiszka wrote:
This is based on Thierry Reding's work and uses Ian Campell's
preparatory patches. It comes with full support for CPU_ON/OFF PSCI
services. The algorithm used in this version for turning CPUs on and
off was proposed by Thierry Reding in
http://thread.gmane.org/gmane.comp.boot-loaders.u-boot/210881. It
consists of first enabling CPU1..3 via the PMC, just to powergate them
again with the help of the Flow Controller. Once the Flow Controller is
in place, we can leave the PMC alone while processing CPU_ON and CPU_OFF
PSCI requests.
diff --git a/arch/arm/cpu/armv7/tegra124/ap.c b/arch/arm/cpu/armv7/tegra124/ap.c
+void ap_pm_init(void)
+{
+ struct flow_ctlr *flow = (struct flow_ctlr *)NV_PA_FLOW_BASE;
+ struct pmc_ctlr *pmc = (struct pmc_ctlr *)NV_PA_PMC_BASE;
+
+ writel((u32)park_cpu, EXCEP_VECTOR_CPU_RESET_VECTOR);
+
+ tegra_powergate_power_on(TEGRA_POWERGATE_CPU1);
+ tegra_powergate_power_on(TEGRA_POWERGATE_CPU2);
+ tegra_powergate_power_on(TEGRA_POWERGATE_CPU3);
+
+ writel((2 << CSR_WAIT_WFI_SHIFT) | CSR_ENABLE, &flow->cpu1_csr);
+ writel((4 << CSR_WAIT_WFI_SHIFT) | CSR_ENABLE, &flow->cpu2_csr);
+ writel((8 << CSR_WAIT_WFI_SHIFT) | CSR_ENABLE, &flow->cpu3_csr);
+
+ writel(EVENT_MODE_STOP, &flow->halt_cpu1_events);
+ writel(EVENT_MODE_STOP, &flow->halt_cpu2_events);
+ writel(EVENT_MODE_STOP, &flow->halt_cpu3_events);
I would expect to set up halt_cpu*_events before powering on the CPUs,
to make sure that they do the expected action on the very first WFI. So,
shouldn't the order above be:
Write to halt_cpu*_events
Write to cpu*_csr
power_on
I didn't review the assembly code at all really; I assume Thierry will.
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