On Monday 21 November 2016 04:38 PM, Jon Hunter wrote:
I had a discussion with the ASIC on this and as per them
1.8 V nominal is (1.62V, 1.98V)
3.3 V nominal is (2.97V,3.63V)
I am working with them to update the TRM document but we can assume that
this information will be there in TRM.
My feeling is that if all use-cases today are using either 1.8V or 3.3V,
then may be we should not worry about this and only support either 1.8V
or 3.3V. I would be more in favour of supporting other voltages if there
is a real need.
Sometimes, the regulator will not return exact 1.8V or 3.3V due to the
PMIC rail resolution. On such cases, it returns nearest voltage to 1.8V
or 3.3V.
That's why the PMIC resolution is considered through IO pad voltage
tolerances.
+ const struct pinctrl_pin_desc *pins_desc;
+ int num_pins_desc;
+};
+
+struct tegra_io_pads_regulator_info {
+ struct device *dev;
+ const struct tegra_io_pads_cfg_info *pads_cfg;
+ struct regulator *regulator;
+ struct notifier_block regulator_nb;
+};
Is this struct necessary? Seems to be a lot of duplicated information
from the other structs. Why not add the regulator and regulator_nb to
the main struct? OK, not all io_pads have a regulator but you are only
saving one pointer.
Yes, some of IO pads support multi-voltage.
Yes, but I am saying why not put this information in the main struct and
not bother having yet another struct where half of the information is
duplicated.
For regulator notifier callback, we will need the driver data. If I keep
this in the main structure then I will not able to get proper structure
until I make that as global.
The notifier registration is
ret = devm_regulator_register_notifier(regulator,
&rinfo->regulator_nb);
and from the pointer of rinfo->regulator_nb, I will get the rinfo as
rinfo = container_of(nb, struct tegra_io_pads_regulator_info,
regulator_nb);
if I use this in main structure then I will not be able to get the
driver data.
+ if ((vdata->old_uV > TEGRA_IO_PAD_1800000UV_UPPER_LIMIT) &&
+ (vdata->min_uV <= TEGRA_IO_PAD_1800000UV_UPPER_LIMIT))
+ break;
The data-sheet for Tegra210 only lists 1.8V or 3.3V as supported
options. Do we need to support a range? Or does the h/w support a range
of voltages? I am just wondering why we cannot check explicitly for 1.8V
or 3.3V and treat anything else as an error.
Two voltage level, not range.
Ok, then I think it would be much simpler if we just support the
voltages we are using today.
Regulator resolution is only reason here to use tolerance.
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