Hi,

On 08/19/2014 11:33 AM, Tuomas Tynkkynen wrote:

From: Tuomas Tynkkynen <redacted>

With closed loop support, the clock rate of the DFLL can be adjusted.

The oscillator itself in the DFLL is a free-running oscillator whose
rate is directly determined the supply voltage. However, the DFLL
module contains logic to compare the DFLL output rate to a fixed
reference clock (51 MHz) and make a decision to either lower or raise
the DFLL supply voltage. The DFLL module can then autonomously change
the supply voltage by communicating with an off-chip PMIC via either I2C
or PWM signals. This driver currently supports only I2C.

Signed-off-by: Tuomas Tynkkynen <redacted>

---
v3: Fix incorrect order of arguments to dfll_scale_dvco_rate
---
  drivers/clk/tegra/clk-dfll.c | 656 ++++++++++++++++++++++++++++++++++++++++++-
  1 file changed, 653 insertions(+), 3 deletions(-)

...

  
  /**
+ * dfll_fetch_i2c_params - query PMIC I2C params from DT & regulator subsystem
+ * @td: DFLL instance
+ *
+ * Read all the parameters required for operation in I2C mode. The parameters
+ * can originate from the device tree or the regulator subsystem.
+ * Returns 0 on success or -err on failure.
+ */
+static int dfll_fetch_i2c_params(struct tegra_dfll *td)
+{
+	struct regmap *regmap;
+	struct device *i2c_dev;
+	struct i2c_client *i2c_client;
+	int vsel_reg, vsel_mask;
+	int ret;
+
+	if (!read_dt_param(td, "nvidia,i2c-fs-rate", &td->i2c_fs_rate))
+		return -EINVAL;
+
+	regmap = regulator_get_regmap(td->vdd_reg);
+	i2c_dev = regmap_get_device(regmap);
+	i2c_client = to_i2c_client(i2c_dev);
+
+	td->i2c_slave_addr = i2c_client->addr;
+
+	ret = regulator_get_hardware_vsel_register(td->vdd_reg,
+						   &vsel_reg,
+						   &vsel_mask);
+	if (ret < 0) {
+		dev_err(td->dev,
+			"regulator unsuitable for DFLL I2C operation\n");
+		return -EINVAL;
+	}
+

It seems that the td->i2c_reg never gets initialized, and we're lucky on 
JetsonTK1 or Norrin. We should initialize the regulator offset here. Like:

td->i2c_reg = vsel_reg;

Thanks,
Vince

+	ret = dfll_build_i2c_lut(td);
+	if (ret) {
+		dev_err(td->dev, "couldn't build I2C LUT\n");
+		return ret;
+	}
+
+	return 0;
+}
+