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cpuidle: tegra: Correctly handle result of arm_cpuidle_simple_enter() 

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>
This commit is contained in:
Dmitry Osipenko 2020-07-09 20:35:32 +03:00 committed by Rafael J. Wysocki
parent ba4f184e12
commit 1170433e66
1 changed files with 20 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

34
drivers/cpuidle/cpuidle-tegra.c
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@ -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 int tegra114_enter_s2idle(struct cpuidle_device *dev,