Re: [PATCH V2 2/2] pinctrl: tegra: Add driver to configure voltage and power of io pads

From: Laxman Dewangan
Date: Mon Nov 21 2016 - 04:52:51 EST

Hi Jon,
I will update the patch per your comment.
Here is answer for some of the query.


On Tuesday 15 November 2016 08:37 PM, Jon Hunter wrote:
On 09/11/16 13:06, Laxman Dewangan wrote:
+ * Macro for 1.8V, keep 200mV as tolerance for deciding that
+ * IO pads should be set for 3.3V (high voltage) or 1.8V.
+ */
+#define TEGRA_IO_PAD_1800000UV_UPPER_LIMIT 2000000
Is there a reference we could add for the source of this information?

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.

+ 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.

+ 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.