From: Dmitry Osipenko <digetx@gmail.com>
Date: Tue, 30 Jul 2019 20:23:40 +0300
Subject: ARM: tegra: Use WFE for power-gating on Tegra30
Git-commit: 91d7ff5aa7e3edd9ab99a424099476ed5667b152
Patch-mainline: v5.5-rc1
References: jsc#SLE-15847
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>
Signed-off-by: Mian Yousaf Kaukab <yousaf.kaukab@suse.com>
---
arch/arm/mach-tegra/sleep-tegra30.S | 4 +++-
drivers/soc/tegra/flowctrl.c | 19 +++++++++++++++++--
2 files changed, 20 insertions(+), 3 deletions(-)
diff --git a/arch/arm/mach-tegra/sleep-tegra30.S b/arch/arm/mach-tegra/sleep-tegra30.S
index b408fa56eb89..3341a12bbb9c 100644
--- a/arch/arm/mach-tegra/sleep-tegra30.S
+++ b/arch/arm/mach-tegra/sleep-tegra30.S
@@ -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
diff --git a/drivers/soc/tegra/flowctrl.c b/drivers/soc/tegra/flowctrl.c
index b6bdeef33db1..eb96a3086d6d 100644
--- a/drivers/soc/tegra/flowctrl.c
+++ b/drivers/soc/tegra/flowctrl.c
@@ -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;
- /* pwr gating on wfi */
- reg |= TEGRA30_FLOW_CTRL_CSR_WFI_CPU0 << cpuid;
+
+ 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 */
--
2.26.2