[PATCH AUTOSEL 5.8 072/132] cpuidle: tegra: Correctly handle result of arm_cpuidle_simple_enter()

Sasha Levin
2020-10-27T00:27:15Z

From: Dmitry Osipenko <digetx@gmail.com>

[ Upstream commit 1170433e6611402b869c583fa1fbfd85106ff066 ]

The enter() callback of CPUIDLE drivers returns index of the entered idle
state on success or a negative value on failure. The negative value could
any negative value, i.e. it doesn't necessarily needs to be a error code.
That's because CPUIDLE core only cares about the fact of failure and not
about the reason of the enter() failure.

Like every other enter() callback, the arm_cpuidle_simple_enter() returns
the entered idle-index on success. Unlike some of other drivers, it never
fails. It happened that TEGRA_C1=index=err=0 in the code of cpuidle-tegra
driver, and thus, there is no problem for the cpuidle-tegra driver created
by the typo in the code which assumes that the arm_cpuidle_simple_enter()
returns a error code.

The arm_cpuidle_simple_enter() also may return a -ENODEV error if CPU_IDLE
is disabled in a kernel's config, but all CPUIDLE drivers are disabled if
CPU_IDLE is disabled, including the cpuidle-tegra driver. So we can't ever
see the error code from arm_cpuidle_simple_enter() today.

Of course the code may get some changes in the future and then the
typo may transform into a real bug, so let's correct the typo! The
tegra_cpuidle_state_enter() is now changed to make it return the entered
idle-index on success and negative error code on fail, which puts it on
par with the arm_cpuidle_simple_enter(), making code consistent in regards
to the error handling.

This patch fixes a minor typo in the code, it doesn't fix any bugs.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/cpuidle/cpuidle-tegra.c | 34 +++++++++++++++++++--------------
1 file changed, 20 insertions(+), 14 deletions(-)

diff --git a/drivers/cpuidle/cpuidle-tegra.c b/drivers/cpuidle/cpuidle-tegra.c
index 150045849d782..30e6816c6737a 100644
--- a/drivers/cpuidle/cpuidle-tegra.c
+++ b/drivers/cpuidle/cpuidle-tegra.c
@@ -172,7 +172,7 @@ static int tegra_cpuidle_coupled_barrier(struct cpuidle_device *dev)
static int tegra_cpuidle_state_enter(struct cpuidle_device *dev,
int index, unsigned int cpu)
{
- int ret;
+ int err;

/*
* CC6 state is the "CPU cluster power-off" state. In order to
@@ -183,9 +183,9 @@ static int tegra_cpuidle_state_enter(struct cpuidle_device *dev,
* CPU cores, GIC and L2 cache).
*/
if (index == TEGRA_CC6) {
- ret = tegra_cpuidle_coupled_barrier(dev);
- if (ret)
- return ret;
+ err = tegra_cpuidle_coupled_barrier(dev);
+ if (err)
+ return err;
}

local_fiq_disable();
@@ -194,15 +194,15 @@ static int tegra_cpuidle_state_enter(struct cpuidle_device *dev,

switch (index) {
case TEGRA_C7:
- ret = tegra_cpuidle_c7_enter();
+ err = tegra_cpuidle_c7_enter();
break;

case TEGRA_CC6:
- ret = tegra_cpuidle_cc6_enter(cpu);
+ err = tegra_cpuidle_cc6_enter(cpu);
break;

default:
- ret = -EINVAL;
+ err = -EINVAL;
break;
}

@@ -210,7 +210,7 @@ static int tegra_cpuidle_state_enter(struct cpuidle_device *dev,
tegra_pm_clear_cpu_in_lp2();
local_fiq_enable();

- return ret;
+ return err ?: index;
}

static int tegra_cpuidle_adjust_state_index(int index, unsigned int cpu)
@@ -236,21 +236,27 @@ static int tegra_cpuidle_enter(struct cpuidle_device *dev,
int index)
{
unsigned int cpu = cpu_logical_map(dev->cpu);
- int err;
+ int ret;

index = tegra_cpuidle_adjust_state_index(index, cpu);
if (dev->states_usage[index].disable)
return -1;

if (index == TEGRA_C1)
- err = arm_cpuidle_simple_enter(dev, drv, index);
+ ret = arm_cpuidle_simple_enter(dev, drv, index);
else
- err = tegra_cpuidle_state_enter(dev, index, cpu);
+ ret = tegra_cpuidle_state_enter(dev, index, cpu);

- if (err && (err != -EINTR || index != TEGRA_CC6))
- pr_err_once("failed to enter state %d err: %d\n", index, err);
+ if (ret < 0) {
+ if (ret != -EINTR || index != TEGRA_CC6)
+ pr_err_once("failed to enter state %d err: %d\n",
+ index, ret);
+ index = -1;
+ } else {
+ index = ret;
+ }

- return err ? -1 : index;
+ return index;
}

static void tegra114_enter_s2idle(struct cpuidle_device *dev,
--
2.25.1