i2c: tegra: Use relaxed versions of readl/writel

There is nothing to synchronize in regards to memory accesses for PIO
transfers and for DMA transfers the DMA API takes care of the syncing.
Tested-by: NThierry Reding <treding@nvidia.com>
Signed-off-by: NDmitry Osipenko <digetx@gmail.com>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

drivers/i2c/busses/i2c-tegra.c

@@ -284,12 +284,12 @@ struct tegra_i2c_dev {
 static void dvc_writel(struct tegra_i2c_dev *i2c_dev, u32 val,
 		       unsigned long reg)
 {
-	writel(val, i2c_dev->base + reg);
+	writel_relaxed(val, i2c_dev->base + reg);
 }
 
 static u32 dvc_readl(struct tegra_i2c_dev *i2c_dev, unsigned long reg)
 {
-	return readl(i2c_dev->base + reg);
+	return readl_relaxed(i2c_dev->base + reg);
 }
 
 /*
@@ -307,16 +307,16 @@ static unsigned long tegra_i2c_reg_addr(struct tegra_i2c_dev *i2c_dev,
 static void i2c_writel(struct tegra_i2c_dev *i2c_dev, u32 val,
 		       unsigned long reg)
 {
-	writel(val, i2c_dev->base + tegra_i2c_reg_addr(i2c_dev, reg));
+	writel_relaxed(val, i2c_dev->base + tegra_i2c_reg_addr(i2c_dev, reg));
 
 	/* Read back register to make sure that register writes completed */
 	if (reg != I2C_TX_FIFO)
-		readl(i2c_dev->base + tegra_i2c_reg_addr(i2c_dev, reg));
+		readl_relaxed(i2c_dev->base + tegra_i2c_reg_addr(i2c_dev, reg));
 }
 
 static u32 i2c_readl(struct tegra_i2c_dev *i2c_dev, unsigned long reg)
 {
-	return readl(i2c_dev->base + tegra_i2c_reg_addr(i2c_dev, reg));
+	return readl_relaxed(i2c_dev->base + tegra_i2c_reg_addr(i2c_dev, reg));
 }
 
 static void i2c_writesl(struct tegra_i2c_dev *i2c_dev, void *data,
@@ -689,12 +689,13 @@ static int tegra_i2c_wait_for_config_load(struct tegra_i2c_dev *i2c_dev)
 		i2c_writel(i2c_dev, I2C_MSTR_CONFIG_LOAD, I2C_CONFIG_LOAD);
 
 		if (i2c_dev->is_curr_atomic_xfer)
-			err = readl_poll_timeout_atomic(addr, val, val == 0,
-							1000,
-							I2C_CONFIG_LOAD_TIMEOUT);
+			err = readl_relaxed_poll_timeout_atomic(
+						addr, val, val == 0, 1000,
+						I2C_CONFIG_LOAD_TIMEOUT);
 		else
-			err = readl_poll_timeout(addr, val, val == 0, 1000,
-						 I2C_CONFIG_LOAD_TIMEOUT);
+			err = readl_relaxed_poll_timeout(
+						addr, val, val == 0, 1000,
+						I2C_CONFIG_LOAD_TIMEOUT);
 
 		if (err) {
 			dev_warn(i2c_dev->dev,