On Mon, Aug 08, 2016 at 07:32:03PM +0300, Antony Pavlov wrote:
> Hi Sascha!
>
> I have just took a look on Lukas'
> 'net: phy: fixed-link: read link parameters from devicetree' patch.
> I see two problems with current 'of_phy_register_fixed_link()' implementation
> unrelated to Lukas' changes.
>
> Please see current of_phy_register_fixed_link() implementation:
>
> static struct phy_device *of_phy_register_fixed_link(struct device_node *np,
> struct eth_device *edev)
> {
> struct phy_device *phydev;
>
> phydev = phy_device_create(NULL, 0, 0);
>
> phydev->dev.parent = &edev->dev;
> phydev->registered = 1;
> phydev->speed = 1000;
> phydev->duplex = 1;
> phydev->pause = phydev->asym_pause = 0;
> phydev->link = 1;
>
> return phydev;
> }
>
> 1. (a trivial think) the line
>
> phydev->link = 1;
>
> is redundant because phy_device_create() has already set it.
Yes, this is redundant and can be removed.
>
> 2. (not so trivial think) the line
>
> phydev->registered = 1;
>
> Why we want to set phydev->registered here? Can we use phy_register_device() instead?
If we use phy_register_device() here then I think the genphy driver is
attached to the fixed link which probably can't handle this fake device.
You can give it a try, but I assume you will see NULL pointer exceptions
in several places.
phydev->registered = 1 is necessary because without this
phy_register_device() is called in phy_device_attach() which is called
from phy_device_connect() called from the network device driver.
There may be ways to properly register a fixed link as a phy device, but
this would mean some serious rework of the phy layer.
Sascha
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