RE: [PATCH 0/2] Add reset deassertion for Aspeed MDIO
From: Dylan Hung
Date: Tue Mar 22 2022 - 05:10:39 EST
Hi Andrew,
> -----Original Message-----
> From: Andrew Lunn [mailto:andrew@xxxxxxx]
> Sent: 2022年3月21日 8:11 PM
> To: Dylan Hung <dylan_hung@xxxxxxxxxxxxxx>
> Cc: robh+dt@xxxxxxxxxx; joel@xxxxxxxxx; andrew@xxxxxxxx;
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> devicetree@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx;
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> Subject: Re: [PATCH 0/2] Add reset deassertion for Aspeed MDIO
>
> On Mon, Mar 21, 2022 at 03:01:29PM +0800, Dylan Hung wrote:
> > Add missing reset deassertion for Aspeed MDIO. There are 4 MDIOs
> > embedded in Aspeed AST2600 and share one reset control bit SCU50[3].
>
> Is the reset limited to the MDIO bus masters, or are PHYs one the bus
> potentially also reset?
It is limited to the MDIO bus masters.
>
> Who asserts the reset in the first place?
The hardware asserts the reset by default.
> Don't you want the first MDIO bus to
> probe to assert and then deassert the reset in order that all the hardware is
> reset?
Do I still need to add a reset assertion/deassertion if the hardware asserts the reset by default?
>
> Andrew
--
Dylan