Re: [PATCH] ARM: shmobile: r8a7740: Fix ethernet device name in clock definition

[Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>]

Hello.

On 22-07-2013 13:15, Shimoda, Yoshihiro wrote:

>>>>>>>>> board code callback in sh_eth_plat_data (.set_mdio_gate) isn't used on
>>>>>>>>> ARM platforms, so the driver should support pure DT bindings without
>>>>>>>>> auxiliary data.

>>>>>>>> Maybe it isn't used on ARM but it exists. IMO that's enough reason not to
>>>>>>>> convert the platform data to the DT properties.

>>>>>>> I don't agree. The proper fix would be to fix the SuperH platform that
>>>>>>> uses that callback (there's one only) to replace the callback function
>>>>>>> with a proper kernel framework.

>>>>>> At least suggest such framework first.

>>>>> I would first need to understand what the board code implementes in the
>>>>> set_mdio_gate() callback. The callback is used by the SH7757LCR board only, do
>>>>> you have access to the board schematics and SH7757 datasheet ?

>>>>      No, only for SH7751 manual by coincidence. This SoC doesn't have Ether.
>>>> Maybe the original commit (sh: add GETHER's platform_device in board-sh7757lcr) author, Shimoda-san, could help us here? I've CC'ed him.

>>> - The SH7757 has 2 MDIO/MDC channels for Gigabit Ethernet.
>>> - The board has VSC8244 Gigabit Ethernet PHY.
>>> - The VSC8244 has 4 MAC channels. But it has one MDIO/MDC port.
>>> - The board's schematic about MDIO/MDC is like below:
>>> +--------+ <--- GETHER ch0's MDIO/MDC ---> +-----------+
>>> | SH7757 | <--- GETHER ch1's MDIO/MDC ---> | bus swith | <--- MDIO/MDC ---> VSC8244
>>> +--------+ <--- GPIO --------------------> +-----------+

>>     You apparently forgot to mention 2 Ether devices for which set_mdio_gate() method is also used (this is introduced by the same patch). What is the GBECONT register you also didn't mention?

> Sorry, I forgot to mention the GBECONT register.
> So, I would like to rewrite my description about .set_mdio_gate() of board-sh7757lcr.c:

> - The SH7757 has 2 Gigabit Ethernet controllers (GETHER) and
>    2 Fast Ethernet controllers (ETHER).
> - The SH7757 has 2 MDIO/MDC channels, but those are multiplexed port.
> - The SH7757 has the GBECONT register:
>   - If "RMII0" is set to 1, the ETHER channel 0 can use the MDIO/MDC channel 0.
>   - If "RMII0" is set to 0, the GETHER channel 0 can use the MDIO/MDC channel 0.
>   - If "RMII1" is set to 1, the ETHER channel 1 can use the MDIO/MDC channel 1.
>   - If "RMII1" is set to 0, the GETHER channel 1 can use the MDIO/MDC channel 1.
> - The board has 2 DP83848C Fast Ethernet PHYs.
> - The board has VSC8244 Gigabit Ethernet PHY.
> - The VSC8244 has 4 MAC channels. But it has one MDIO/MDC port.
> - The board's schematic about MDIO/MDC is like below:
> +--------+                     +--> DP83848C
> |        | <-- MDIO/MDC ch 0 --+--> +------------+
> | SH7757 | <-- GPIO --------------> | bus switch | <-- MDIO/MDC --> VSC8244
> |        | <-- MDIO/MDC ch 1 --+--> +------------+
> +--------+                     +--> DP83848C
> - About the bus switch:
>   - If the GPIO is set to high, the bus switch will conenct the MDIO/MDC ch 0 to VSC8244.
>   - If the GPIO is set to low, the bus switch will conenct the MDIO/MDC ch 1 to VSC8244.
>
> So, if the ETHER channel 0 wants to use the MDIO/MDC ch 0,
> the "RMII0" should be set to 1.
> So, if the GETHER channel 0 wants to use the MDIO/MDC ch 0,
> the "RMII0" should be set to 0 and the GPIO should be set to High.

    Thank you for the quick replies, Shimoda-san.

> Best regards,
> Yoshihiro Shimoda

WBR, Sergei