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@xxxxxxxxx>
---
Changelog:
v3: The tegra_cpuidle_state_enter() now returns entered idle-index on
success instead of 0. Hence the error message will be shown by the
tegra-cpuidle driver if arm_cpuidle_simple_enter() will ever fail.
Again thanks to Jon Hunter!
v2: Improved commit message by clarifying what values are returned by
arm_cpuidle_simple_enter() and when. Thanks to Jon Hunter for the
suggestion!
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 150045849d78..30e6816c6737 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,
--
2.26.0
