On Wed, Oct 28, 2020 at 03:22:32PM +1000, Greg Ungerer wrote:
> Some (apparently older) versions of the FEC hardware block do not like
> the MMFR register being cleared to avoid generation of MII events at
> initialization time. The action of clearing this register results in no
> future MII events being generated at all on the problem block. This means
> the probing of the MDIO bus will find no PHYs.
>
> Create a quirk that can be checked at the FECs MII init time so that
> the right thing is done. The quirk is set as appropriate for the FEC
> hardware blocks that are known to need this.
>
> Fixes: f166f890c8f0 ("net: ethernet: fec: Replace interrupt driven MDIO with
> polled IO")
> Signed-off-by: Greg Ungerer <g...@linux-m68k.org>
> ---
> drivers/net/ethernet/freescale/fec.h | 6 +++++
> drivers/net/ethernet/freescale/fec_main.c | 29 +++++++++++++----------
> 2 files changed, 22 insertions(+), 13 deletions(-)
>
> v2: use quirk for imx28 as well
>
> Resending for consideration based on Andy's last comment that this fix
> is enough on its own for all hardware types.
>
> diff --git a/drivers/net/ethernet/freescale/fec.h
> b/drivers/net/ethernet/freescale/fec.h
> index 832a2175636d..c527f4ee1d3a 100644
> --- a/drivers/net/ethernet/freescale/fec.h
> +++ b/drivers/net/ethernet/freescale/fec.h
> @@ -456,6 +456,12 @@ struct bufdesc_ex {
> */
> #define FEC_QUIRK_HAS_FRREG (1 << 16)
>
> +/* Some FEC hardware blocks need the MMFR cleared at setup time to avoid
> + * the generation of an MII event. This must be avoided in the older
> + * FEC blocks where it will stop MII events being generated.
> + */
> +#define FEC_QUIRK_CLEAR_SETUP_MII (1 << 17)
> +
> struct bufdesc_prop {
> int qid;
> /* Address of Rx and Tx buffers */
> diff --git a/drivers/net/ethernet/freescale/fec_main.c
> b/drivers/net/ethernet/freescale/fec_main.c
> index fb37816a74db..65784d3e54a5 100644
> --- a/drivers/net/ethernet/freescale/fec_main.c
> +++ b/drivers/net/ethernet/freescale/fec_main.c
> @@ -100,14 +100,14 @@ static const struct fec_devinfo fec_imx27_info = {
> static const struct fec_devinfo fec_imx28_info = {
> .quirks = FEC_QUIRK_ENET_MAC | FEC_QUIRK_SWAP_FRAME |
> FEC_QUIRK_SINGLE_MDIO | FEC_QUIRK_HAS_RACC |
> - FEC_QUIRK_HAS_FRREG,
> + FEC_QUIRK_HAS_FRREG | FEC_QUIRK_CLEAR_SETUP_MII,
> };
>
> static const struct fec_devinfo fec_imx6q_info = {
> .quirks = FEC_QUIRK_ENET_MAC | FEC_QUIRK_HAS_GBIT |
> FEC_QUIRK_HAS_BUFDESC_EX | FEC_QUIRK_HAS_CSUM |
> FEC_QUIRK_HAS_VLAN | FEC_QUIRK_ERR006358 |
> - FEC_QUIRK_HAS_RACC,
> + FEC_QUIRK_HAS_RACC | FEC_QUIRK_CLEAR_SETUP_MII,
> };
>
> static const struct fec_devinfo fec_mvf600_info = {
> @@ -119,7 +119,8 @@ static const struct fec_devinfo fec_imx6x_info = {
> FEC_QUIRK_HAS_BUFDESC_EX | FEC_QUIRK_HAS_CSUM |
> FEC_QUIRK_HAS_VLAN | FEC_QUIRK_HAS_AVB |
> FEC_QUIRK_ERR007885 | FEC_QUIRK_BUG_CAPTURE |
> - FEC_QUIRK_HAS_RACC | FEC_QUIRK_HAS_COALESCE,
> + FEC_QUIRK_HAS_RACC | FEC_QUIRK_HAS_COALESCE |
> + FEC_QUIRK_CLEAR_SETUP_MII,
> };
>
> static const struct fec_devinfo fec_imx6ul_info = {
> @@ -127,7 +128,7 @@ static const struct fec_devinfo fec_imx6ul_info = {
> FEC_QUIRK_HAS_BUFDESC_EX | FEC_QUIRK_HAS_CSUM |
> FEC_QUIRK_HAS_VLAN | FEC_QUIRK_ERR007885 |
> FEC_QUIRK_BUG_CAPTURE | FEC_QUIRK_HAS_RACC |
> - FEC_QUIRK_HAS_COALESCE,
> + FEC_QUIRK_HAS_COALESCE | FEC_QUIRK_CLEAR_SETUP_MII,
> };
>
> static struct platform_device_id fec_devtype[] = {
> @@ -2114,15 +2115,17 @@ static int fec_enet_mii_init(struct platform_device
> *pdev)
> if (suppress_preamble)
> fep->phy_speed |= BIT(7);
>
> - /* Clear MMFR to avoid to generate MII event by writing MSCR.
> - * MII event generation condition:
> - * - writing MSCR:
> - * - mmfr[31:0]_not_zero & mscr[7:0]_is_zero &
> - * mscr_reg_data_in[7:0] != 0
> - * - writing MMFR:
> - * - mscr[7:0]_not_zero
> - */
> - writel(0, fep->hwp + FEC_MII_DATA);
> + if (fep->quirks & FEC_QUIRK_CLEAR_SETUP_MII) {
> + /* Clear MMFR to avoid to generate MII event by writing MSCR.
> + * MII event generation condition:
> + * - writing MSCR:
> + * - mmfr[31:0]_not_zero & mscr[7:0]_is_zero &
> + * mscr_reg_data_in[7:0] != 0
> + * - writing MMFR:
> + * - mscr[7:0]_not_zero
> + */
> + writel(0, fep->hwp + FEC_MII_DATA);
> + }
>
> writel(fep->phy_speed, fep->hwp + FEC_MII_SPEED);
>
> --
> 2.25.1
>
This fixes the problem on i.MX6Q!
Tested-by: Clemens Gruber <clemens.gru...@pqgruber.com>
Best regards,
Clemens
