On Thu, Jan 19, 2017 at 09:47:33AM -0800, David Daney wrote:
> On 01/19/2017 06:50 AM, Jan Glauber wrote:
> [...]
> >
> >>4) GPIO powers should be modelled as GPIO regulators. I believe we
> >>have discussed this earlier as well (I don't really recall in detail
> >>about the last things). It gives us the opportunity to via the
> >>regulator framework to find out the supported voltage levels. This is
> >>the generic method which is used by mmc drivers, you need to adopt to
> >>this as well.
> >
> >I've added a fixed regulator to DT:
> >
> > vcc_3v3: regulator-vcc_3v3 {
> > compatible = "regulator-fixed";
> > regulator-name = "VCC_3V3";
>
>
> Very minor point not really directly related to the MMC driver:
> "VCC_3V3" implies a general purpose supply for many things on the
> board. This is not the case for these boards. The "regulator"
> controls power only to eMMC and SD devices, so a name that conveys
> that function should be invented.
OK, I'll rename it to:
mmc_supply_3v3: mmc_supply_3v3 {
compatible = "regulator-fixed";
regulator-name = "mmc_supply_3v3";
[...]
> Actually on some boards GPIO 8 doesn't even control a regulator, but
> instead only activates a bus isolator on the control and data
> signals to the eMMC and SD devices. In this case we would be using
> the regulator framework only because the code is already there and
> it happens to work, not because we actually have a regulator.
>
> > regulator-min-microvolt = <3300000>;
> > regulator-max-microvolt = <3300000>;
> >
> > gpio = <&gpio_6_0 8 0>;
> > /* enable-gpio = <&gpio_6_0 8 0>; */
> > enable-active-high;
> > };
> >
> >This seems to enable the gpio. Is this sufficient or do I need the
> >gpio-regulator?
> >
>
> Does the "regulator-fixed" allow us to properly turn it on and off?
Yes, I've disabled all gpio calls from our mmc driver, with only the gpio
settings in the regulator entry I get:
root@sff:~# cat /sys/kernel/debug/gpio
gpiochip0: GPIOs 464-511, parent: pci/0000:00:06.0, gpio_thunderx:
gpio-472 ( |mmc_supply_3v3 ) out hi
So the regulator driver enables GPIO 8 as it should.
> If not, we may have to switch to "gpio-regulator". Which ever is
> simplest should be used.
"regulator-fixed" seems sufficient to me as we don't need the additional
power states that "gpio-regulator" supports.
> [...]
