| Message ID | 20200709173532.15431-1-digetx@gmail.com (mailing list archive) |
|---|---|
| State | Mainlined, archived |
| Headers | show |
| Series | [v3] cpuidle: tegra: Correctly handle result of arm_cpuidle_simple_enter() | expand |
09.07.2020 20:35, Dmitry Osipenko пишет: > 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> > --- > > 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! Hello, Jon! Do you see anything else that could be improved in this patch?
On 14/08/2020 18:53, Dmitry Osipenko wrote: > 09.07.2020 20:35, Dmitry Osipenko пишет: >> 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> >> --- >> >> 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! > > Hello, Jon! Do you see anything else that could be improved in this patch? > Sorry for the delay. Looks good to me ... Reviewed-by: Jon Hunter <jonathanh@nvidia.com> Cheers Jon
24.08.2020 19:02, Jon Hunter пишет: > > On 14/08/2020 18:53, Dmitry Osipenko wrote: >> 09.07.2020 20:35, Dmitry Osipenko пишет: >>> 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> >>> --- >>> >>> 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! >> >> Hello, Jon! Do you see anything else that could be improved in this patch? >> > > Sorry for the delay. Looks good to me ... > > Reviewed-by: Jon Hunter <jonathanh@nvidia.com> No problems, thank you! :)
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,
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> --- 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(-)