On 14.08.2019 00:53, Florian Fainelli wrote:
> On 8/13/19 2:25 PM, Heiner Kallweit wrote:
>> In cases like a fixed phy that is never attached to a net_device we
>> may want to bind the genphy driver at probe time. Setting a PHY ID of
>> 0xffffffff to bind the genphy driver would fail due to a check in
>> get_phy_device(). Therefore let's change the PHY ID the genphy driver
>> binds to to 0xfffffffe. This still shouldn't match any real PHY,
>> and it will pass the check in get_phy_devcie().
>>
>> Signed-off-by: Heiner Kallweit <hkallwe...@gmail.com>
>> ---
>> drivers/net/phy/phy_device.c | 3 +--
>> include/linux/phy.h | 4 ++++
>> 2 files changed, 5 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
>> index 163295dbc..54f80af31 100644
>> --- a/drivers/net/phy/phy_device.c
>> +++ b/drivers/net/phy/phy_device.c
>> @@ -2388,8 +2388,7 @@ void phy_drivers_unregister(struct phy_driver *drv,
>> int n)
>> EXPORT_SYMBOL(phy_drivers_unregister);
>>
>> static struct phy_driver genphy_driver = {
>> - .phy_id = 0xffffffff,
>> - .phy_id_mask = 0xffffffff,
>> + PHY_ID_MATCH_EXACT(GENPHY_ID),
>> .name = "Generic PHY",
>> .soft_reset = genphy_no_soft_reset,
>> .get_features = genphy_read_abilities,
>> diff --git a/include/linux/phy.h b/include/linux/phy.h
>> index 5ac7d2137..3b07bce78 100644
>> --- a/include/linux/phy.h
>> +++ b/include/linux/phy.h
>> @@ -37,6 +37,10 @@
>> #define PHY_1000BT_FEATURES (SUPPORTED_1000baseT_Half | \
>> SUPPORTED_1000baseT_Full)
>>
>> +#define GENPHY_ID_HIGH 0xffffU
>> +#define GENPHY_ID_LOW 0xfffeU
>> +#define GENPHY_ID ((GENPHY_ID_HIGH << 16) | GENPHY_ID_LOW)
>
> This is a possible user ABI change here, if there is anything that
> relies on reading 0xffff_ffff as a valid PHY OUI, you would be breaking
> it. We might as well try to assign ourselves a specific PHY OUI, very
> much like the Linux USB hubs show up with a Linux Foundation vendor ID.
>
I see the point. However in get_phy_device() we have the following check
that should cause a PHY with ID 0xffff_ffff to be ignored. Therefore
I doubt there's any such PHY ID in use.
/* If the phy_id is mostly Fs, there is no device there */
if ((phy_id & 0x1fffffff) == 0x1fffffff)
return ERR_PTR(-ENODEV);
Heiner
