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Date: Sat, 14 May 2016 21:50:16 +0200 From: Andrew Lunn <andrew@...n.ch> To: Sergei Shtylyov <sergei.shtylyov@...entembedded.com> Cc: Roger Quadros <rogerq@...com>, Uwe Kleine-König <u.kleine-koenig@...gutronix.de>, grant.likely@...aro.org, robh+dt@...nel.org, devicetree@...r.kernel.org, f.fainelli@...il.com, netdev@...r.kernel.org, frowand.list@...il.com, pawel.moll@....com, mark.rutland@....com, ijc+devicetree@...lion.org.uk, galak@...eaurora.org, linux-kernel@...r.kernel.org, Linus Walleij <linus.walleij@...aro.org> Subject: Re: [PATCH RFT 1/2] phylib: add device reset GPIO support On Sat, May 14, 2016 at 10:36:38PM +0300, Sergei Shtylyov wrote: > Hello. > > On 05/14/2016 02:44 AM, Andrew Lunn wrote: > > >>>>>Another issue is that on some boards we have one reset line tied to > >>>>>multiple PHYs.How do we prevent multiple resets being taking place when each of > >>>>>the PHYs are registered? > >>>> > >>>> My patch just doesn't address this case -- it's about the > >>>>individual resets only. > >>> > >>>This actually needs to be addresses a layer above. What you have is a > >>>bus reset, not a device reset. > >> > >> No. > >> There's simply no such thing as a bus reset for the xMII/MDIO > >>busses, there's simply no reset signaling on them. Every device has > >>its own reset signal and its own timing requirements. > > > >Except in the case above, where two phys are sharing the same reset > >signal. So although it is not part of the mdio standard to have a bus > >reset, this is in effect what the gpio line is doing, resetting all > >devices on the bus. If you don't model that as a bus reset, how do you > >model it? > > I'm not suggesting that the shared reset should be handled by my > patch. Contrariwise, I suggested to use the mii_bus::reset() method I think we miss understood each other somewhere. Your code is great for one gpio reset line for one phy. I think there could be similar code one layer above to handle one gpio line for multiple phys. Andrew
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