Re: [PATCH v3 2/2] net: dsa: mt7530: Use GPIO polarity to generate correct reset sequence

["Russell King (Oracle)" <linux@armlinux.org.uk>]

On Thu, Dec 04, 2025 at 06:32:23PM +0100, Krzysztof Kozlowski wrote:
> On 04/12/2025 18:23, Krzysztof Kozlowski wrote:
> > On 04/12/2025 18:11, Vladimir Oltean wrote:
> >> On Thu, Dec 04, 2025 at 05:48:07PM +0100, Krzysztof Kozlowski wrote:
> >>> Both are the same - inverter or NOT gate, same stuff. It is just
> >>> connecting wire to pull up, not actual component on the board (although
> >>> one could make and buy such component as well...). We never describe
> >>> these inverters in the DTS, these are just too trivial circuits, thus
> >>> the final GPIO_ACTIVE_XXX should already include whatever is on the wire
> >>> between SoC and device.
> >>
> >> Please read what Andrew said:
> >> https://lore.kernel.org/netdev/3fbc4e67-b931-421c-9d83-2214aaa2f6ed@lunn.ch/
> >>
> >>   Assuming there is not a NOT gate placed between the GPIO and the reset
> >>   pin, because the board designer decided to do that for some reason?
> >>                    ~~~~~~~~~~~~~~
> >>
> >> You two are *not* talking about the same thing. I dismissed the
> > 
> > 
> > It's the same thing. NOT gate is just pulling some pin down or up.
> 
> Although transistor would be still needed, so indeed that's still a bit
> more than a wire and resistor as I implied.
> 
> It looks like:
> https://www.electronics-tutorials.ws/wp-content/uploads/2018/05/logic-log47.gif

A bit more than even that... I do hope folk don't use exactly that,
that's the kind of thing that would be used in "learning about
electronics" projects! That's a recipe to drive a transistor into
full saturation, which makes it comparitively very slow to turn off.

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