From mboxrd@z Thu Jan 1 00:00:00 1970 From: Florian Fainelli Subject: Re: [PATCH] net: phy: allow scanning busses with missing phys Date: Tue, 24 Apr 2018 09:37:09 -0700 Message-ID: <2833f30a-cf95-e5c7-e44f-218929e61024@gmail.com> References: <20180424160904.32457-1-alexandre.belloni@bootlin.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Cc: "David S . Miller" , Allan Nielsen , Thomas Petazzoni , netdev@vger.kernel.org, linux-kernel@vger.kernel.org To: Alexandre Belloni , Andrew Lunn Return-path: In-Reply-To: <20180424160904.32457-1-alexandre.belloni@bootlin.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On 04/24/2018 09:09 AM, Alexandre Belloni wrote: > Some MDIO busses will error out when trying to read a phy address with no > phy present at that address. In that case, probing the bus will fail > because __mdiobus_register() is scanning the bus for all possible phys > addresses. > > In case MII_PHYSID1 returns -EIO or -ENODEV, consider there is no phy at > this address and set the phy ID to 0xffffffff which is then properly > handled in get_phy_device(). Humm, why not have your MDIO bus implementation do the scanning itself in a reset() callback, which happens before probing the bus, and based on the results, set phy_mask accordingly such that only PHYs present are populated? My only concern with your change is that we are having a special treatment for EIO and ENODEV, so we must make sure MDIO bus drivers are all conforming to that. > > Suggested-by: Andrew Lunn > Signed-off-by: Alexandre Belloni > --- > drivers/net/phy/phy_device.c | 11 ++++++++++- > 1 file changed, 10 insertions(+), 1 deletion(-) > > diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c > index ac23322a32e1..9e4ba8e80a18 100644 > --- a/drivers/net/phy/phy_device.c > +++ b/drivers/net/phy/phy_device.c > @@ -535,8 +535,17 @@ static int get_phy_id(struct mii_bus *bus, int addr, u32 *phy_id, > > /* Grab the bits from PHYIR1, and put them in the upper half */ > phy_reg = mdiobus_read(bus, addr, MII_PHYSID1); > - if (phy_reg < 0) > + if (phy_reg < 0) { > + /* if there is no device, return without an error so scanning > + * the bus works properly > + */ > + if (phy_reg == -EIO || phy_reg == -ENODEV) { > + *phy_id = 0xffffffff; > + return 0; > + } > + > return -EIO; > + } > > *phy_id = (phy_reg & 0xffff) << 16; > > -- Florian