ARM: tegra: Use WFE for power-gating on Tegra30 (91d7ff5a) · Commits · 戴 / test

Turned out that WFI doesn't work reliably on Tegra30 as a trigger for the power-gating, it causes CPU hang under some circumstances like having memory controller running of PLLP. The TRM doc states that WFI should be used for the Big-Little "Cluster Switch", while WFE for the power-gating. Hence let's use the WFE for CPU0 power-gating, like it is done for the power-gating of a secondary cores. This fixes CPU hang after entering LP2 with memory running off PLLP. Acked-by:

Peter De Schrijver <pdeschrijver@nvidia.com> Signed-off-by:

Dmitry Osipenko <digetx@gmail.com> Tested-by:

Peter Geis <pgwipeout@gmail.com> Signed-off-by:

Thierry Reding <treding@nvidia.com>

arch/arm/mach-tegra/sleep-tegra30.S

+3 −1

Original line number	Diff line number	Diff line
		@@ -682,10 +682,12 @@ tegra30_enter_sleep:
		dsb
		ldr r0, [r6, r2] /* memory barrier */

		cmp r10, #TEGRA30
		halted:
		isb
		dsb
		wfi /* CPU should be power gated here */
		wfine /* CPU should be power gated here */
		wfeeq

		/* !!!FIXME!!! Implement halt failure handler */
		b halted

drivers/soc/tegra/flowctrl.c

+17 −2

Original line number	Diff line number	Diff line
		@@ -91,8 +91,23 @@ void flowctrl_cpu_suspend_enter(unsigned int cpuid)
		reg &= ~TEGRA30_FLOW_CTRL_CSR_WFE_BITMAP;
		/* clear wfi bitmap */
		reg &= ~TEGRA30_FLOW_CTRL_CSR_WFI_BITMAP;

		if (tegra_get_chip_id() == TEGRA30) {
		/*
		* The wfi doesn't work well on Tegra30 because
		* CPU hangs under some odd circumstances after
		* power-gating (like memory running off PLLP),
		* hence use wfe that is working perfectly fine.
		* Note that Tegra30 TRM doc clearly stands that
		* wfi should be used for the "Cluster Switching",
		* while wfe for the power-gating, just like it
		* is done on Tegra20.
		*/
		reg \|= TEGRA20_FLOW_CTRL_CSR_WFE_CPU0 << cpuid;
		} else {
		/* pwr gating on wfi */
		reg \|= TEGRA30_FLOW_CTRL_CSR_WFI_CPU0 << cpuid;
		}
		break;
		}
		reg \|= FLOW_CTRL_CSR_INTR_FLAG; /* clear intr flag */

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