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 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html