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Message-ID: <5832C005.3070104@nvidia.com>
Date: Mon, 21 Nov 2016 15:06:05 +0530
From: Laxman Dewangan <ldewangan@...dia.com>
To: Jon Hunter <jonathanh@...dia.com>, <linus.walleij@...aro.org>,
<robh+dt@...nel.org>, <mark.rutland@....com>,
<swarren@...dotorg.org>, <thierry.reding@...il.com>
CC: <gnurou@...il.com>, <yamada.masahiro@...ionext.com>,
<linux-gpio@...r.kernel.org>, <devicetree@...r.kernel.org>,
<linux-tegra@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH V2 2/2] pinctrl: tegra: Add driver to configure voltage
and power of io pads
Hi Jon,
I will update the patch per your comment.
Here is answer for some of the query.
Thanks,
Laxman
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.
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