Re: [PATCH] pinctrl: sh-pfc: r8a7791: add EtherAVB pin groups

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

Hello.

On 12/8/2015 3:12 PM, Geert Uytterhoeven wrote:

>> Add the EtherAVB pin groups to the R8A7791 PFC driver.
>
> Thanks for your patch!
>
>> +static const unsigned int avb_mii_pins[] = {
>> +       RCAR_GP_PIN(5, 18), RCAR_GP_PIN(5, 19), RCAR_GP_PIN(5, 20),
>> +       RCAR_GP_PIN(5, 21),
>> +
>> +       RCAR_GP_PIN(5, 0), RCAR_GP_PIN(5, 1), RCAR_GP_PIN(5, 2),
>> +       RCAR_GP_PIN(5, 3),
>> +
>> +       RCAR_GP_PIN(5, 8), RCAR_GP_PIN(5, 13), RCAR_GP_PIN(5, 10),
>> +       RCAR_GP_PIN(5, 15), RCAR_GP_PIN(5, 26), RCAR_GP_PIN(5, 28),
>> +       RCAR_GP_PIN(5, 29),
>> +};
>> +static const unsigned int avb_mii_mux[] = {
>> +       AVB_TXD0_MARK, AVB_TXD1_MARK, AVB_TXD2_MARK,
>> +       AVB_TXD3_MARK,
>> +
>> +       AVB_RXD0_MARK, AVB_RXD1_MARK, AVB_RXD2_MARK,
>> +       AVB_RXD3_MARK,
>> +
>> +       AVB_RX_ER_MARK, AVB_RX_CLK_MARK, AVB_RX_DV_MARK,
>> +       AVB_CRS_MARK, AVB_TX_EN_MARK, AVB_TX_CLK_MARK,
>> +       AVB_COL_MARK,
>> +};
>
> The MII pin list include RX_ER, but not TX_ER...

    Wikipedia tells me TX_ER is optional for MII.

> ... while the GMII pin list includes both RX_ER and TX_ER. Is that correct?
> Should it be the other way around?
>
> Section "45A.3.13.1 MII Frame Transmission/Reception Timing" of the R-Car Gen2
> datasheet shows timing diagrams for both AVB_TX_ER and AVB_RX_ER, so I'd expect
> both pins to be needed for MII.

    Hm, interesting...

> Unfortunately Section "45A.3.13.2 GMII Frame Reception Timing" shows timing
> diagrams for receive only (thus involving AVB_RX_ER only), so I'm not sure the
> AVB_TX_ER pin is actually needed for GMII.

    It is.

> I don't have schematics for any R-Car Gen2 board that has AVB support, so I
> can't check myself how the MII/GMII is really wired.

    The standard Lager/Porter boards require some modification to use an an 
AVB daughter board, AFAIK.

> Note that this also applies to the existing AVB pinmux data in pfc-r8a7790.c.

    And we haven't really tested MII, only GMII.

[...]

> Gr{oetje,eeting}s,
>
>                          Geert

MBR, Sergei