linux-kernel - [PATCH V2 4/4] soc/tegra: pmc: Make configuration of IO pads in atomic context

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Date:   Wed, 9 Nov 2016 18:39:22 +0530
From:   Laxman Dewangan <ldewangan@...dia.com>
To:     <thierry.reding@...il.com>, <swarren@...dotorg.org>
CC:     <gnurou@...il.com>, <jonathanh@...dia.com>,
        <linux-tegra@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        Laxman Dewangan <ldewangan@...dia.com>
Subject: [PATCH V2 4/4] soc/tegra: pmc: Make configuration of IO pads in atomic context

The IO pad voltage configuration can be done in the regulator
notifier callback which is atomic in nature.

Replace the mutex with spin lock for the locking mechanism.

Signed-off-by: Laxman Dewangan <ldewangan@...dia.com>

---
Changes from V1:
 New in series based on pinctrl driver requirement.
---
 drivers/soc/tegra/pmc.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/soc/tegra/pmc.c b/drivers/soc/tegra/pmc.c
index 916a94b..52cd218 100644
--- a/drivers/soc/tegra/pmc.c
+++ b/drivers/soc/tegra/pmc.c
@@ -172,6 +172,7 @@ struct tegra_pmc_soc {
  * @lp0_vec_size: size of the LP0 warm boot code
  * @powergates_available: Bitmap of available power gates
  * @powergates_lock: mutex for power gate register access
+ * @io_pad_lock: Spinlock for IO pad voltage register access
  * @plat_subdevs: Platform device for PMC child devices.
  */
 struct tegra_pmc {
@@ -199,6 +200,7 @@ struct tegra_pmc {
 	DECLARE_BITMAP(powergates_available, TEGRA_POWERGATE_MAX);
 
 	struct mutex powergates_lock;
+	struct spinlock io_pad_lock;
 	struct platform_device **plat_subdevs;
 };
 
@@ -1103,7 +1105,7 @@ int tegra_io_pad_set_voltage(enum tegra_io_pad id,
 	if (pad->voltage == UINT_MAX)
 		return -ENOTSUPP;
 
-	mutex_lock(&pmc->powergates_lock);
+	spin_lock(&pmc->io_pad_lock);
 
 	/* write-enable PMC_PWR_DET_VALUE[pad->voltage] */
 	value = tegra_pmc_readl(PMC_PWR_DET);
@@ -1120,7 +1122,7 @@ int tegra_io_pad_set_voltage(enum tegra_io_pad id,
 
 	tegra_pmc_writel(value, PMC_PWR_DET_VALUE);
 
-	mutex_unlock(&pmc->powergates_lock);
+	spin_unlock(&pmc->io_pad_lock);
 
 	usleep_range(100, 250);
 
@@ -1800,6 +1802,7 @@ static int __init tegra_pmc_early_init(void)
 	u32 value;
 
 	mutex_init(&pmc->powergates_lock);
+	spin_lock_init(&pmc->io_pad_lock);
 
 	np = of_find_matching_node_and_match(NULL, tegra_pmc_match, &match);
 	if (!np) {
-- 
2.1.4