From: Andrew Lunn <andrew@lunn.ch>
To: Russell King - ARM Linux admin <linux@armlinux.org.uk>
Cc: Jeremy Linton <jeremy.linton@arm.com>,
netdev@vger.kernel.org, davem@davemloft.net,
f.fainelli@gmail.com, hkallweit1@gmail.com,
madalin.bucur@oss.nxp.com, calvin.johnson@oss.nxp.com,
linux-kernel@vger.kernel.org
Subject: Re: [RFC 03/11] net: phy: refactor c45 phy identification sequence
Date: Sat, 23 May 2020 21:51:31 +0200 [thread overview]
Message-ID: <20200523195131.GN610998@lunn.ch> (raw)
In-Reply-To: <20200523183058.GX1551@shell.armlinux.org.uk>
> > static int get_phy_c45_ids(struct mii_bus *bus, int addr, u32 *phy_id,
> > struct phy_c45_device_ids *c45_ids) {
> > - int phy_reg;
> > - int i, reg_addr;
> > + int ret;
> > + int i;
> > const int num_ids = ARRAY_SIZE(c45_ids->device_ids);
> > u32 *devs = &c45_ids->devices_in_package;
>
> I feel a "reverse christmas tree" complaint brewing... yes, the original
> code didn't follow it. Maybe a tidy up while touching this code?
At minimum, a patch should not make it worse. ret and i should clearly
be after devs.
> > static int get_phy_id(struct mii_bus *bus, int addr, u32 *phy_id,
> > bool is_c45, struct phy_c45_device_ids *c45_ids)
> > {
> > - int phy_reg;
> > + int ret;
> >
> > if (is_c45)
> > return get_phy_c45_ids(bus, addr, phy_id, c45_ids);
> >
> > - /* Grab the bits from PHYIR1, and put them in the upper half */
> > - phy_reg = mdiobus_read(bus, addr, MII_PHYSID1);
> > - if (phy_reg < 0) {
> > + ret = _get_phy_id(bus, addr, 0, phy_id, false);
> > + if (ret < 0) {
> > /* returning -ENODEV doesn't stop bus scanning */
> > - return (phy_reg == -EIO || phy_reg == -ENODEV) ? -ENODEV : -EIO;
> > + return (ret == -EIO || ret == -ENODEV) ? -ENODEV : -EIO;
>
> Since ret will only ever be -EIO here, this can only ever return
> -ENODEV, which is a functional change in the code (probably unintended.)
> Nevertheless, it's likely introducing a bug if the intention is for
> some other return from mdiobus_read() to be handled differently.
>
> > }
> >
> > - *phy_id = phy_reg << 16;
> > -
> > - /* Grab the bits from PHYIR2, and put them in the lower half */
> > - phy_reg = mdiobus_read(bus, addr, MII_PHYSID2);
> > - if (phy_reg < 0)
> > - return -EIO;
>
> ... whereas this one always returns -EIO on any error.
>
> So, I think you have the potential in this patch to introduce a subtle
> change of behaviour, which may lead to problems - have you closely
> analysed why the code was the way it was, and whether your change of
> behaviour is actually valid?
I could be remembering this wrongly, but i think this is to do with
orion_mdio_xsmi_read() returning -ENODEV, not 0xffffffffff, if there
is no device on the bus at the given address. -EIO is fatal to the
scan, everything stops with the assumption the bus is broken. -ENODEV
should not be fatal to the scan.
Andrew
next prev parent reply other threads:[~2020-05-23 19:51 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-22 21:30 [RFC 00/11] Make C45 autoprobe more robust Jeremy Linton
2020-05-22 21:30 ` [RFC 01/11] net: phy: Don't report success if devices weren't found Jeremy Linton
2020-05-23 18:20 ` Russell King - ARM Linux admin
2020-05-25 2:46 ` Jeremy Linton
2020-05-25 9:45 ` Russell King - ARM Linux admin
2020-05-25 21:02 ` Jeremy Linton
2020-05-25 21:07 ` Russell King - ARM Linux admin
2020-05-25 21:59 ` Jeremy Linton
2020-05-22 21:30 ` [RFC 02/11] net: phy: Simplify MMD device list termination Jeremy Linton
2020-05-23 18:36 ` Russell King - ARM Linux admin
2020-05-25 2:48 ` Jeremy Linton
2020-05-25 8:09 ` Russell King - ARM Linux admin
2020-05-22 21:30 ` [RFC 03/11] net: phy: refactor c45 phy identification sequence Jeremy Linton
2020-05-23 15:28 ` Andrew Lunn
2020-05-23 17:16 ` Jeremy Linton
2020-05-23 17:32 ` Jeremy Linton
2020-05-23 19:12 ` Russell King - ARM Linux admin
2020-05-23 18:30 ` Russell King - ARM Linux admin
2020-05-23 19:51 ` Andrew Lunn [this message]
2020-05-23 20:01 ` Russell King - ARM Linux admin
2020-05-25 2:37 ` Jeremy Linton
2020-05-22 21:30 ` [RFC 04/11] net: phy: Handle c22 regs presence better Jeremy Linton
2020-05-23 18:37 ` Russell King - ARM Linux admin
2020-05-25 3:34 ` Jeremy Linton
2020-05-25 9:53 ` Russell King - ARM Linux admin
2020-05-25 10:06 ` Russell King - ARM Linux admin
2020-05-25 21:51 ` Jeremy Linton
2020-05-25 22:01 ` Russell King - ARM Linux admin
2020-05-25 22:22 ` Jeremy Linton
2020-05-25 23:09 ` Russell King - ARM Linux admin
2020-05-25 23:22 ` Jeremy Linton
2020-05-25 23:33 ` Russell King - ARM Linux admin
2020-05-25 23:42 ` Jeremy Linton
2020-05-25 23:46 ` Andrew Lunn
2020-05-25 23:57 ` Russell King - ARM Linux admin
2020-05-25 23:16 ` Jeremy Linton
2020-05-25 23:30 ` Russell King - ARM Linux admin
2020-05-25 22:06 ` Andrew Lunn
2020-05-25 22:17 ` Jeremy Linton
2020-05-25 23:06 ` Andrew Lunn
2020-05-25 23:07 ` Russell King - ARM Linux admin
2020-05-25 23:12 ` Andrew Lunn
2020-05-25 23:46 ` Jeremy Linton
2020-05-25 23:47 ` Andrew Lunn
2020-05-22 21:30 ` [RFC 05/11] net: phy: Scan the entire MMD device space Jeremy Linton
2020-05-22 21:30 ` [RFC 06/11] net: phy: Hoist no phy detected state Jeremy Linton
2020-05-22 21:30 ` [RFC 07/11] net: phy: reset invalid phy reads of 0 back to 0xffffffff Jeremy Linton
2020-05-23 18:44 ` Russell King - ARM Linux admin
2020-05-25 4:20 ` Jeremy Linton
2020-05-25 8:20 ` Russell King - ARM Linux admin
2020-05-22 21:30 ` [RFC 08/11] net: phy: Allow mdio buses to auto-probe c45 devices Jeremy Linton
2020-05-24 14:44 ` Andrew Lunn
2020-05-25 4:28 ` Jeremy Linton
2020-05-25 8:25 ` Russell King - ARM Linux admin
2020-05-25 13:43 ` Andrew Lunn
2020-05-25 22:09 ` Jeremy Linton
2020-05-25 22:41 ` Russell King - ARM Linux admin
2020-05-22 21:30 ` [RFC 09/11] net: phy: Refuse to consider phy_id=0 a valid phy Jeremy Linton
2020-05-22 21:30 ` [RFC 10/11] net: example acpize xgmac_mdio Jeremy Linton
2020-05-23 18:48 ` Russell King - ARM Linux admin
2020-05-22 21:30 ` [RFC 11/11] net: example xgmac enable extended scanning Jeremy Linton
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