[PATCH 0/2] Add reset deassertion for Aspeed MDIO

Dylan Hung dylan_hung at aspeedtech.com
Tue Mar 22 20:10:28 AEDT 2022

Hi Andrew,

> -----Original Message-----
> From: Andrew Lunn [mailto:andrew at lunn.ch]
> Sent: 2022年3月21日 8:11 PM
> To: Dylan Hung <dylan_hung at aspeedtech.com>
> Cc: robh+dt at kernel.org; joel at jms.id.au; andrew at aj.id.au;
> hkallweit1 at gmail.com; linux at armlinux.org.uk; davem at davemloft.net;
> kuba at kernel.org; pabeni at redhat.com; p.zabel at pengutronix.de;
> devicetree at vger.kernel.org; linux-arm-kernel at lists.infradead.org;
> linux-aspeed at lists.ozlabs.org; linux-kernel at vger.kernel.org;
> netdev at vger.kernel.org; BMC-SW <BMC-SW at aspeedtech.com>
> 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


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