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SubjectRE: [PATCH] net/phy: tune get_phy_c45_ids to support more c45 phy
Date


> -----Original Message-----
> From: David Miller [mailto:davem@davemloft.net]
> Sent: Monday, April 13, 2015 8:42 AM
> To: Liu Shengzhou-B36685
> Cc: netdev@vger.kernel.org; linux-kernel@vger.kernel.org;
> f.fainelli@gmail.com
> Subject: Re: [PATCH] net/phy: tune get_phy_c45_ids to support more c45 phy
>
> From: Shengzhou Liu <Shengzhou.Liu@freescale.com>
> Date: Fri, 10 Apr 2015 17:10:20 +0800
>
> > if ((c45_ids->devices_in_package & 0x1fffffff) == 0x1fffffff) {
> > - *phy_id = 0xffffffff;
> > - return 0;
> > + reg_addr = MII_ADDR_C45 | 0 << 16 | 6;
> > + phy_reg = mdiobus_read(bus, addr, reg_addr);
> > + if (phy_reg < 0)
> > + return -EIO;
>
> Why are you reading this same register again, and why are you doing it with
> the magic constant "6". That's not '6', it's 'MDIO_DEVS2'.
>
> The first loop executed here should have read from this address, and placed
> the value into the ->devices_in_package.
>
> This looks really like a hack. You're reading again the same registers, by
> hand, that the loop should already be reading properly.
>
> Why not restructure the loop to actually probe naturally for the presence
> bits in a way that works on the chip you are trying to make work?

Some PHYs(e.g. Cortina CS4315/CS4340) have zero Devices In package,
If we first probe zero Devices In package by loop for(i = 0; i < num_ids && c45_ids->devices_in_package == 0; i++),
it will cause the probe fail on those C45 PHYs with non-zero Devices In package.
So we must first probe non-zero Devices In package in the loop, if the return value
of c45_ids->devices_in_package is 0x1fffffff, then try to probe zero Devices In package.
Yes, will use MDIO_DEVS1 and MDIO_DEVS2 instead of constant '6', '5' in next version.


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