[U-Boot] [RFC PATCH] net: gem: Add support for more PHYs on MDIO bus

[Michal Simek]

On 6.2.2018 22:11, Joe Hershberger wrote:
> On Mon, Feb 5, 2018 at 1:17 AM, Michal Simek <michal.simek at xilinx.com> wrote:
>> Hi Joe,
>>
>> On 2.2.2018 20:35, Joe Hershberger wrote:
>>> Hi Michal,
>>>
>>> On Thu, Feb 1, 2018 at 6:42 AM, Michal Simek <michal.simek at xilinx.com> wrote:
>>>> Find out MDIO bus and enable MDIO access to it if this is done via
>>>> different controller.
>>>>
>>>> Signed-off-by: Michal Simek <michal.simek at xilinx.com>
>>>> ---
>>>>
>>>> Hi Joe,
>>>>
>>>> this is the code I have hacked a year ago for ZynqMP where we can have
>>>> configuration that 4 gems are enabled but they share the same MDIO bus
>>>> which can be assigned to only gem. Normally recommendation is that you
>>>> should assign it to IP which is required for boot and this is suitable I
>>>> would say for almost everybody.
>>>> But for testing purpose it will be good to support sharing mdio bus
>>>> between others IPs. This hack is "enabling" this for others gem but not
>>>> across different ethernet drivers.
>>>
>>> Seems practical.
>>>
>>>> And my question is if there is any solution which can be used now for
>>>> handling it. Or even this should work even now but we do something
>>>> wrong.
>>>
>>> I would envision some DM way to model the NIC, the MDIO bus, and the
>>> PHY separately. The big roadblock is that the DTS format is different
>>> for every NIC.
>>
>> Is it really that different? There should be phy handle which is
>> pointing to actual phy and that should be enough to recognize parents
>> and IP responsible for MDIO bus.
> 
> The point is different drivers express the relationship with varying
> levels of implication, so there are a number of ways people describe
> it.

ok.

> 
>>>> I am refreshing this topic based on communication with Tomasz
>>>> Gorochowik when he wanted to separate mdio part but it is not compatible
>>>> with solution used in Linux which is pattern we should follow.
>>>
>>> We do the same thing on our 7020 products.
>>
>> What exactly are you doing on 7020?
> 
> We are using a single MDIO interface to connect the PHYs for 2 GEMs.

And I expect you are using only one interface for boot right?

M