On 17/07/15 11:17, Thierry Reding wrote:
> * PGP Signed by an unknown key
>
> On Mon, Jul 13, 2015 at 01:39:45PM +0100, Jon Hunter wrote:
>> Currently, the function tegra_powergate_set() simply sets the desired
>> powergate state but does not wait for the state to change. In some
>> circumstances this can be desirable. However, in most cases we should
>> wait for the state to change before proceeding. Therefore, add a
>> parameter to tegra_powergate_set() to indicate whether we should wait
>> for the state to change.
>>
>> By adding this feature, we can also eliminate the polling loop from
>> tegra30_boot_secondary().
>>
>> Signed-off-by: Jon Hunter <jonathanh@xxxxxxxxxx>
>> ---
>> arch/arm/mach-tegra/platsmp.c | 18 ++++--------------
>> drivers/soc/tegra/pmc.c | 29 +++++++++++++++++++++++------
>> include/soc/tegra/pmc.h | 2 +-
>> 3 files changed, 28 insertions(+), 21 deletions(-)
>>
>> diff --git a/arch/arm/mach-tegra/platsmp.c b/arch/arm/mach-tegra/platsmp.c
>> index b45086666648..13982b5936c0 100644
>> --- a/arch/arm/mach-tegra/platsmp.c
>> +++ b/arch/arm/mach-tegra/platsmp.c
>> @@ -108,19 +108,9 @@ static int tegra30_boot_secondary(unsigned int cpu, struct task_struct *idle)
>> * be un-gated by un-toggling the power gate register
>> * manually.
>> */
>> - if (!tegra_pmc_cpu_is_powered(cpu)) {
>> - ret = tegra_pmc_cpu_power_on(cpu);
>> - if (ret)
>> - return ret;
>> -
>> - /* Wait for the power to come up. */
>> - timeout = jiffies + msecs_to_jiffies(100);
>> - while (!tegra_pmc_cpu_is_powered(cpu)) {
>> - if (time_after(jiffies, timeout))
>> - return -ETIMEDOUT;
>> - udelay(10);
>> - }
>> - }
>> + ret = tegra_pmc_cpu_power_on(cpu, true);
>> + if (ret)
>> + return ret;
>>
>> remove_clamps:
>> /* CPU partition is powered. Enable the CPU clock. */
>> @@ -162,7 +152,7 @@ static int tegra114_boot_secondary(unsigned int cpu, struct task_struct *idle)
>> * also initial power state in flow controller. After that,
>> * the CPU's power state is maintained by flow controller.
>> */
>> - ret = tegra_pmc_cpu_power_on(cpu);
>> + ret = tegra_pmc_cpu_power_on(cpu, false);
>> }
>>
>> return ret;
>> diff --git a/drivers/soc/tegra/pmc.c b/drivers/soc/tegra/pmc.c
>> index 300f11e0c3bb..c0635bdd4ee3 100644
>> --- a/drivers/soc/tegra/pmc.c
>> +++ b/drivers/soc/tegra/pmc.c
>> @@ -175,9 +175,11 @@ static void tegra_pmc_writel(u32 value, unsigned long offset)
>> * @id: partition ID
>> * @new_state: new state of the partition
>
> The comment here isn't updated.
>
>> */
>> -static int tegra_powergate_set(int id, bool new_state)
>> +static int tegra_powergate_set(int id, bool new_state, bool wait)
>
> Can we please not chain boolean parameters, it makes the call sites
> impossible to parse for humans. Instead, can we simply leave
> tegra_powergate_set() as it is and add another function, such as
> tegra_powergate_set_sync() or tegra_powergate_set_and_wait(), to achieve
> the same? You may have to split out a tegra_powergate_set_unlocked() or
> similar to make sure you get to keep the lock across both operations:
>
> static int tegra_powergate_set_unlocked(int id, bool new_state)
> {
> ...
> }
>
> static int tegra_powergate_set(int id, bool new_state)
> {
> int err;
>
> mutex_lock(&pmc->powergates_lock);
> err = tegra_powergate_set_unlocked(id, new_state);
> mutex_unlock(&pmc->powergates_lock);
>
> return err;
> }
>
> /*
> * Must be called with pmc->powergates_lock mutex held.
> */
> static int tegra_powergate_wait(int id, bool new_state)
> {
> ...
> }
>
> static int tegra_powergate_set_and_wait(int id, bool new_state)
> {
> int err;
>
> mutex_lock(&pmc->powergates_lock);
>
> err = tegra_powergate_set_unlocked(id, new_state);
> if (err < 0)
> goto unlock;
>
> err = tegra_powergate_wait(id, new_state);
> if (err < 0)
> goto unlock;
>
> unlock:
> mutex_unlock(&pmc->powergates_lock);
> return err;
> }
>
>> {
>> + unsigned long timeout;
>> bool status;
>> + int ret = 0;
>>
>> mutex_lock(&pmc->powergates_lock);
>>
>> @@ -190,9 +192,23 @@ static int tegra_powergate_set(int id, bool new_state)
>>
>> tegra_pmc_writel(PWRGATE_TOGGLE_START | id, PWRGATE_TOGGLE);
>>
>> + if (wait) {
>> + timeout = jiffies + msecs_to_jiffies(100);
>> + ret = -ETIMEDOUT;
>> +
>> + while (time_before(jiffies, timeout)) {
>> + status = !!(tegra_pmc_readl(PWRGATE_STATUS) & BIT(id));
>> + if (status == new_state) {
>> + ret = 0;
>> + break;
>> + }
>> + udelay(10);
>> + }
>> + }
>> +
>> mutex_unlock(&pmc->powergates_lock);
>>
>> - return 0;
>> + return ret;
>> }
>>
>> /**
>> @@ -204,7 +220,7 @@ int tegra_powergate_power_on(int id)
>> if (!pmc->soc || id < 0 || id >= pmc->soc->num_powergates)
>> return -EINVAL;
>>
>> - return tegra_powergate_set(id, true);
>> + return tegra_powergate_set(id, true, true);
>> }
>>
>> /**
>> @@ -216,7 +232,7 @@ int tegra_powergate_power_off(int id)
>> if (!pmc->soc || id < 0 || id >= pmc->soc->num_powergates)
>> return -EINVAL;
>>
>> - return tegra_powergate_set(id, false);
>> + return tegra_powergate_set(id, false, true);
>> }
>> EXPORT_SYMBOL(tegra_powergate_power_off);
>>
>> @@ -351,8 +367,9 @@ bool tegra_pmc_cpu_is_powered(int cpuid)
>> /**
>> * tegra_pmc_cpu_power_on() - power on CPU partition
>> * @cpuid: CPU partition ID
>> + * @wait: Wait for CPU state to transition
>> */
>> -int tegra_pmc_cpu_power_on(int cpuid)
>> +int tegra_pmc_cpu_power_on(int cpuid, bool wait)
>
> This one is probably fine since it's the only boolean parameter so far.
> That said, I see that we call this exactly twice, so I wonder if there'd
> be any harm in having the second occurrence wait as well and hence get
> rid of the parameter.
I would agree and think we should drop the 2nd parameter and just always
wait. This is only done at boot time and so would only add a little
delay at that point.
Cheers
Jon
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