[PATCH V6 06/10] soc: tegra: pmc: Wait for powergate state to change

[Jon Hunter <jonathanh-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>]

Currently, the function tegra_powergate_set() simply sets the desired
powergate state but does not wait for the state to change. In most cases
we should wait for the state to change before proceeding. Currently, there
is a case for tegra114 and tegra124 devices where we do not wait when
starting the secondary CPU as this is not necessary. However, this is only
done at boot time and so waiting here will only have a small impact on
boot time. Therefore, update tegra_powergate_set() to wait when setting
the powergate.

By adding this feature, we can also eliminate the polling loop from
tegra30_boot_secondary().

A function has been added for checking the status of the powergate and
so update the tegra_powergate_is_powered() to use this macro as well.

Signed-off-by: Jon Hunter <jonathanh-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
---
 arch/arm/mach-tegra/platsmp.c | 16 +++-------------
 drivers/soc/tegra/pmc.c       |  9 ++++++++-
 2 files changed, 11 insertions(+), 14 deletions(-)

diff --git a/arch/arm/mach-tegra/platsmp.c b/arch/arm/mach-tegra/platsmp.c
index f3f61dbbda97..75620ae73913 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);
+	if (ret)
+		return ret;
 
 remove_clamps:
 	/* CPU partition is powered. Enable the CPU clock. */
diff --git a/drivers/soc/tegra/pmc.c b/drivers/soc/tegra/pmc.c
index e4fd40fa27e8..08966c26d65c 100644
--- a/drivers/soc/tegra/pmc.c
+++ b/drivers/soc/tegra/pmc.c
@@ -28,6 +28,7 @@
 #include <linux/export.h>
 #include <linux/init.h>
 #include <linux/io.h>
+#include <linux/iopoll.h>
 #include <linux/of.h>
 #include <linux/of_address.h>
 #include <linux/platform_device.h>
@@ -194,6 +195,9 @@ static inline bool tegra_powergate_is_valid(int id)
  */
 static int tegra_powergate_set(unsigned int id, bool new_state)
 {
+	bool status;
+	int err;
+
 	if (id == TEGRA_POWERGATE_3D && pmc->soc->has_gpu_clamps)
 		return -EINVAL;
 
@@ -206,9 +210,12 @@ static int tegra_powergate_set(unsigned int id, bool new_state)
 
 	tegra_pmc_writel(PWRGATE_TOGGLE_START | id, PWRGATE_TOGGLE);
 
+	err = readx_poll_timeout(tegra_powergate_state, id, status,
+				 status == new_state, 10, 100000);
+
 	mutex_unlock(&pmc->powergates_lock);
 
-	return 0;
+	return err;
 }
 
 /**
-- 
2.1.4