Re: [PATCH 01/13] clk: tegra: Add binding for the Tegra124 DFLL clocksource

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On 11/07/14 20:08, Andrew Bresticker wrote:
On Fri, Jul 11, 2014 at 9:48 AM, Tuomas Tynkkynen <ttynkkynen@xxxxxxxxxx> wrote:


On 11/07/14 19:28, Andrew Bresticker wrote:

On Thu, Jul 10, 2014 at 2:42 PM, Tuomas Tynkkynen <ttynkkynen@xxxxxxxxxx>
wrote:

The DFLL is the main clocksource for the fast CPU cluster on Tegra124
and also provides automatic CPU rail voltage scaling as well. The DFLL
is a separate IP block from the usual Tegra124 clock-and-reset
controller, so it gets its own node in the device tree.


diff --git
a/Documentation/devicetree/bindings/clock/nvidia,tegra124-dfll.txt
b/Documentation/devicetree/bindings/clock/nvidia,tegra124-dfll.txt


+- nvidia,pmic-voltage-table: Array of 2-tuples.  Each entry should have
the
+  form <register-value voltage-in-uV>, indicating the register value
that
+  needs to be programmed to the PMIC for changing the VDD_CPU voltage to
+  the specified voltage. The table must be in ascending order by the
voltage.


Instead of listing the register values for each voltage in the DT,
can't you use regulator_list_voltage() to create this map?


I don't see a way to get the register values that way, unless we assume that
the mapping is linear and doesn't have holes.

Hmm... I guess if you don't assume it's linear and continuous you'd
have to iterate over all 256 selectors.


I don't think we can assume that each selector maps to a concrete register value, though I'm not sure. include/linux/regulator/driver.h documents for @list_voltage "Selectors range from zero to one less regulator_desc.n_voltages." but maybe the consumer API could take different values.

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