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Re: [PATCH v4] ARM: dts: sun8i: Add dts file for Olimex A33-OLinuXino

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  Re: [PATCH v4] ARM: dts: sun8i: Add dts file for Olimex A33-OLinuXino Maxime Ripard <maxime.ripard@free-electrons.com> - 2016-07-26 17:40 +0200
    Re: [PATCH v4] ARM: dts: sun8i: Add dts file for Olimex A33-OLinuXino stefan.mavrodiev@gmail.com - 2016-07-27 07:20 +0200
      Re: [PATCH v4] ARM: dts: sun8i: Add dts file for Olimex A33-OLinuXino Maxime Ripard <maxime.ripard@free-electrons.com> - 2016-07-27 08:30 +0200
        Re: [PATCH v4] ARM: dts: sun8i: Add dts file for Olimex A33-OLinuXino stefan.mavrodiev@gmail.com - 2016-07-27 12:10 +0200
          Re: [PATCH v4] ARM: dts: sun8i: Add dts file for Olimex A33-OLinuXino Maxime Ripard <maxime.ripard@free-electrons.com> - 2016-07-28 20:00 +0200

#1450656 — Re: [PATCH v4] ARM: dts: sun8i: Add dts file for Olimex A33-OLinuXino

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Hi Stefan,

On Mon, Jul 25, 2016 at 03:37:23PM +0300, Stefan Mavrodiev wrote:
> A33-OLinuXino is A33 development board designed by Olimex LTD.
> 
> It has AXP233 PMU, 1GB DRAM, a micro SD card, one USB-OTG connector,
> headphone and mic jacks, connector for LiPo battery and optional
> 4GB NAND Flash.
> 
> It has two 40-pin headers. One for LCD panel, and one for
> additional modules. Also there is CSI/DSI connector.
> 
> Signed-off-by: Stefan Mavrodiev <stefan.mavrodiev@gmail.com>

It looks mostly good, a few comments though.
> +&pio {
> +	led_pin_olinuxino: led_pins@0 {
> +		allwinner,pins = "PB7";
> +        allwinner,function = "gpio_out";

This line is not properly indented.

> +		allwinner,drive = <SUN4I_PINCTRL_10_MA>;
> +		allwinner,pull = <SUN4I_PINCTRL_NO_PULL>;
> +    };

And this one too.

> +&reg_dc1sw {
> +	regulator-name = "vcc-lcd";
> +};

No constraints on this one?

> +&reg_dcdc1 {
> +	regulator-always-on;
> +	regulator-min-microvolt = <3300000>;
> +	regulator-max-microvolt = <3300000>;
> +	regulator-name = "vcc-dsi";
> +};

What is it used for? Is it really necessary to keep it on at all time?

Thanks,
Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

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#1451044

On Tuesday, July 26, 2016 5:33:52 PM EEST Maxime Ripard wrote:
> Hi Stefan,
> 
> On Mon, Jul 25, 2016 at 03:37:23PM +0300, Stefan Mavrodiev wrote:
> > A33-OLinuXino is A33 development board designed by Olimex LTD.
> > 
> > It has AXP233 PMU, 1GB DRAM, a micro SD card, one USB-OTG connector,
> > headphone and mic jacks, connector for LiPo battery and optional
> > 4GB NAND Flash.
> > 
> > It has two 40-pin headers. One for LCD panel, and one for
> > additional modules. Also there is CSI/DSI connector.
> > 
> > Signed-off-by: Stefan Mavrodiev <stefan.mavrodiev@gmail.com>
> 
> It looks mostly good, a few comments though.
> 
> > +&pio {
> > +	led_pin_olinuxino: led_pins@0 {
> > +		allwinner,pins = "PB7";
> > +        allwinner,function = "gpio_out";
> 
> This line is not properly indented.
> 
> > +		allwinner,drive = <SUN4I_PINCTRL_10_MA>;
> > +		allwinner,pull = <SUN4I_PINCTRL_NO_PULL>;
> > +    };
> 
> And this one too.
> 
> > +&reg_dc1sw {
> > +	regulator-name = "vcc-lcd";
> > +};
> 
> No constraints on this one?
> 
> > +&reg_dcdc1 {
> > +	regulator-always-on;
> > +	regulator-min-microvolt = <3300000>;
> > +	regulator-max-microvolt = <3300000>;
> > +	regulator-name = "vcc-dsi";
> > +};
> 
> What is it used for? Is it really necessary to keep it on at all time?

I think so.
This is the supply for the MMC.
> 
> Thanks,
> Maxime

Best regards,
Stefan Mavrodiev

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#1451063

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On Wed, Jul 27, 2016 at 08:12:29AM +0300, stefan.mavrodiev@gmail.com wrote:
> > > +&reg_dcdc1 {
> > > +	regulator-always-on;
> > > +	regulator-min-microvolt = <3300000>;
> > > +	regulator-max-microvolt = <3300000>;
> > > +	regulator-name = "vcc-dsi";
> > > +};
> > 
> > What is it used for? Is it really necessary to keep it on at all time?
> 
> I think so.
> This is the supply for the MMC.

Then it's poorly named, and you should tie it to the MMC, and remove
the always-on if it's only used by the mmc. always-on is supposed to
be for regulators that shouldn't but turned off for the system to stay
running. Some MMC regulator doesn't fit that description.

Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

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#1451203

On Wednesday, July 27, 2016 8:21:46 AM EEST Maxime Ripard wrote:
> On Wed, Jul 27, 2016 at 08:12:29AM +0300, stefan.mavrodiev@gmail.com wrote:
> > > > +&reg_dcdc1 {
> > > > +	regulator-always-on;
> > > > +	regulator-min-microvolt = <3300000>;
> > > > +	regulator-max-microvolt = <3300000>;
> > > > +	regulator-name = "vcc-dsi";
> > > > +};
> > > 
> > > What is it used for? Is it really necessary to keep it on at all time?
> > 
> > I think so.
> > This is the supply for the MMC.
> 
> Then it's poorly named, and you should tie it to the MMC, and remove
> the always-on if it's only used by the mmc. always-on is supposed to
> be for regulators that shouldn't but turned off for the system to stay
> running. Some MMC regulator doesn't fit that description.
> 
It's named upon the A33 power pin - "VCC-DSI". 
If I remove "always-on" the board still will work, since dcdc1 is tied to 
mmc0. 
vmmc-supply = <&reg_dcdc1>;

We assume this voltage will be always present and there are some pullups that 
are tied to it (on i2c0 and i2c1 bus).  In this case should I remove "always-
on" from the regulator node?

> Maxime

Best regards,
Stefan Mavrodiev

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#1452028

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On Wed, Jul 27, 2016 at 01:02:41PM +0300, stefan.mavrodiev@gmail.com wrote:
> On Wednesday, July 27, 2016 8:21:46 AM EEST Maxime Ripard wrote:
> > On Wed, Jul 27, 2016 at 08:12:29AM +0300, stefan.mavrodiev@gmail.com wrote:
> > > > > +&reg_dcdc1 {
> > > > > +	regulator-always-on;
> > > > > +	regulator-min-microvolt = <3300000>;
> > > > > +	regulator-max-microvolt = <3300000>;
> > > > > +	regulator-name = "vcc-dsi";
> > > > > +};
> > > > 
> > > > What is it used for? Is it really necessary to keep it on at all time?
> > > 
> > > I think so.
> > > This is the supply for the MMC.
> > 
> > Then it's poorly named, and you should tie it to the MMC, and remove
> > the always-on if it's only used by the mmc. always-on is supposed to
> > be for regulators that shouldn't but turned off for the system to stay
> > running. Some MMC regulator doesn't fit that description.
>
> It's named upon the A33 power pin - "VCC-DSI".

Usually, it's based on the name of the output in the schematics,
precisely because, from one board to another, it might have different
usage.

> If I remove "always-on" the board still will work, since dcdc1 is tied to 
> mmc0. 
> vmmc-supply = <&reg_dcdc1>;
> 
> We assume this voltage will be always present and there are some pullups that 
> are tied to it (on i2c0 and i2c1 bus).  In this case should I remove "always-
> on" from the regulator node?

No, you should just tie that regulator to the i2c buses as well.

Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

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