Re: [PATCH] net: phy: Fix c45 no phy detected logic

[Jeremy Linton]

Hi,

On 5/14/20 2:59 PM, Heiner Kallweit wrote:
> On 14.05.2020 19:00, Jeremy Linton wrote:
> > The commit "disregard Clause 22 registers present bit..." clears
> > the low bit of the devices_in_package data which is being used
> > in get_phy_c45_ids() to determine if a phy/register is responding
> > correctly. That check is against 0x1FFFFFFF, but since the low
> > bit is always cleared, the check can never be true. This leads to
> > detecting c45 phy devices where none exist.
> >
> > Lets fix this by also clearing the low bit in the mask to 0x1FFFFFFE.
> > This allows us to continue to autoprobe standards compliant devices
> > without also gaining a large number of bogus ones.
> >
> > Fixes: 3b5e74e0afe3 ("net: phy: disregard "Clause 22 registers present" bit in get_phy_c45_devs_in_pkg")
> > Cc: Heiner Kallweit <hkallweit1@xxxxxxxxx>
> > Signed-off-by: Jeremy Linton <jeremy.linton@xxxxxxx>
> > ---
> >   drivers/net/phy/phy_device.c | 4 ++--
> >   1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
> > index ac2784192472..b93d984d35cc 100644
> > --- a/drivers/net/phy/phy_device.c
> > +++ b/drivers/net/phy/phy_device.c
> > @@ -723,7 +723,7 @@ static int get_phy_c45_ids(struct mii_bus *bus, int addr, u32 *phy_id,
> >   		if (phy_reg < 0)
> >   			return -EIO;
> >   
> > -		if ((*devs & 0x1fffffff) == 0x1fffffff) {
> > +		if ((*devs & 0x1ffffffe) == 0x1ffffffe) {
> >   			/*  If mostly Fs, there is no device there,
>
> Looks good to me, it would just be good to extend the comment and explain
> why we exclude bit 0 here.

Sure, sounds good.

> >   			 *  then let's continue to probe more, as some
> >   			 *  10G PHYs have zero Devices In package,
> > @@ -733,7 +733,7 @@ static int get_phy_c45_ids(struct mii_bus *bus, int addr, u32 *phy_id,
> >   			if (phy_reg < 0)
> >   				return -EIO;
> >   			/* no device there, let's get out of here */
> > -			if ((*devs & 0x1fffffff) == 0x1fffffff) {
> > +			if ((*devs & 0x1ffffffe) == 0x1ffffffe) {
> >   				*phy_id = 0xffffffff;
> >   				return 0;
> >   			} else {