by Daniel Golle

[permalink] [raw]

Subject: Re: [PATCH net-next v2 07/15] net: dsa: mt7530: move MT753X_MTRAP operations for MT7530

Hi Arınç,

On Mon, Apr 22, 2024 at 10:15:14AM +0300, Arınç ÜNAL via B4 Relay wrote:
> From: Arınç ÜNAL <[email protected]>
>
> On MT7530, the media-independent interfaces of port 5 and 6 are controlled
> by the MT7530_P5_DIS and MT7530_P6_DIS bits of the hardware trap. Deal with
> these bits only when the relevant port is being enabled or disabled. This
> ensures that these ports will be disabled when they are not in use.
>
> Do not set MT7530_CHG_TRAP on mt7530_setup_port5() as that's already being
> done on mt7530_setup().

Multiple users reported ([1], [2]) that after I've imported the series
to OpenWrt they noticed that WAN connection on MT7621 boards using
PHY-muxing to hook up either port 0 or port 4 to GMAC1 no longer works.

The link still seems to come up, but no data flows. I went ahead and
confirmed the bug, then started bisecting the patches of this series,
and ended up identifying this very patch being the culprit.

I can't exclude that what ever the issue may be is caused by other
downstream patches we have, but can confirm that removing this patch of
your series [3] in OpenWrt fixes the issue. Please take a look and as
the cover letter states you have tested this on some MT7621 board,
please make sure traffic actually flows on the PHY-muxed port on that
board after this patch is applied, and if not, please figure out why and
repost a fixed version of this patch.

Cheers

Daniel

[1]: https://github.com/openwrt/openwrt/issues/15273
[2]: https://github.com/openwrt/openwrt/issues/15279
[3]: https://git.openwrt.org/?p=openwrt/openwrt.git;a=commit;h=a8dde7e5bd6d289db6485cf57d3512ea62eaa827

>
> Instead of globally setting MT7530_P5_MAC_SEL, clear it, then set it only
> on the appropriate case.
>
> If PHY muxing is detected, clear MT7530_P5_DIS before calling
> mt7530_setup_port5().
>
> Signed-off-by: Arınç ÜNAL <[email protected]>
> ---
> drivers/net/dsa/mt7530.c | 38 +++++++++++++++++++++++++++-----------
> 1 file changed, 27 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/net/dsa/mt7530.c b/drivers/net/dsa/mt7530.c
> index 606516206fb9..83436723cb16 100644
> --- a/drivers/net/dsa/mt7530.c
> +++ b/drivers/net/dsa/mt7530.c
> @@ -880,8 +880,7 @@ static void mt7530_setup_port5(struct dsa_switch *ds, phy_interface_t interface)
>
> val = mt7530_read(priv, MT753X_MTRAP);
>
> - val |= MT7530_CHG_TRAP | MT7530_P5_MAC_SEL | MT7530_P5_DIS;
> - val &= ~MT7530_P5_RGMII_MODE & ~MT7530_P5_PHY0_SEL;
> + val &= ~MT7530_P5_PHY0_SEL & ~MT7530_P5_MAC_SEL & ~MT7530_P5_RGMII_MODE;
>
> switch (priv->p5_mode) {
> /* MUX_PHY_P0: P0 -> P5 -> SoC MAC */
> @@ -891,15 +890,13 @@ static void mt7530_setup_port5(struct dsa_switch *ds, phy_interface_t interface)
>
> /* MUX_PHY_P4: P4 -> P5 -> SoC MAC */
> case MUX_PHY_P4:
> - val &= ~MT7530_P5_MAC_SEL & ~MT7530_P5_DIS;
> -
> /* Setup the MAC by default for the cpu port */
> mt7530_write(priv, MT753X_PMCR_P(5), 0x56300);
> break;
>
> /* GMAC5: P5 -> SoC MAC or external PHY */
> default:
> - val &= ~MT7530_P5_DIS;
> + val |= MT7530_P5_MAC_SEL;
> break;
> }
>
> @@ -1193,6 +1190,14 @@ mt7530_port_enable(struct dsa_switch *ds, int port,
>
> mutex_unlock(&priv->reg_mutex);
>
> + if (priv->id != ID_MT7530 && priv->id != ID_MT7621)
> + return 0;
> +
> + if (port == 5)
> + mt7530_clear(priv, MT753X_MTRAP, MT7530_P5_DIS);
> + else if (port == 6)
> + mt7530_clear(priv, MT753X_MTRAP, MT7530_P6_DIS);
> +
> return 0;
> }
>
> @@ -1211,6 +1216,14 @@ mt7530_port_disable(struct dsa_switch *ds, int port)
> PCR_MATRIX_CLR);
>
> mutex_unlock(&priv->reg_mutex);
> +
> + if (priv->id != ID_MT7530 && priv->id != ID_MT7621)
> + return;
> +
> + if (port == 5)
> + mt7530_set(priv, MT753X_MTRAP, MT7530_P5_DIS);
> + else if (port == 6)
> + mt7530_set(priv, MT753X_MTRAP, MT7530_P6_DIS);
> }
>
> static int
> @@ -2401,11 +2414,11 @@ mt7530_setup(struct dsa_switch *ds)
> mt7530_rmw(priv, MT7530_TRGMII_RD(i),
> RD_TAP_MASK, RD_TAP(16));
>
> - /* Enable port 6 */
> - val = mt7530_read(priv, MT753X_MTRAP);
> - val &= ~MT7530_P6_DIS & ~MT7530_PHY_INDIRECT_ACCESS;
> - val |= MT7530_CHG_TRAP;
> - mt7530_write(priv, MT753X_MTRAP, val);
> + /* Allow modifying the trap and directly access PHY registers via the
> + * MDIO bus the switch is on.
> + */
> + mt7530_rmw(priv, MT753X_MTRAP, MT7530_CHG_TRAP |
> + MT7530_PHY_INDIRECT_ACCESS, MT7530_CHG_TRAP);
>
> if ((val & MT7530_XTAL_MASK) == MT7530_XTAL_40MHZ)
> mt7530_pll_setup(priv);
> @@ -2488,8 +2501,11 @@ mt7530_setup(struct dsa_switch *ds)
> break;
> }
>
> - if (priv->p5_mode == MUX_PHY_P0 || priv->p5_mode == MUX_PHY_P4)
> + if (priv->p5_mode == MUX_PHY_P0 ||
> + priv->p5_mode == MUX_PHY_P4) {
> + mt7530_clear(priv, MT753X_MTRAP, MT7530_P5_DIS);
> mt7530_setup_port5(ds, interface);
> + }
> }
>
> #ifdef CONFIG_GPIOLIB
>
> --
> 2.40.1
>
>

2024-04-27 11:40:56

by Arınç ÜNAL

[permalink] [raw]

Subject: Re: [PATCH net-next v2 07/15] net: dsa: mt7530: move MT753X_MTRAP operations for MT7530

On 27.04.2024 05:24, Daniel Golle wrote:
> Hi Arınç,
>
> On Mon, Apr 22, 2024 at 10:15:14AM +0300, Arınç ÜNAL via B4 Relay wrote:
>> From: Arınç ÜNAL <[email protected]>
>>
>> On MT7530, the media-independent interfaces of port 5 and 6 are controlled
>> by the MT7530_P5_DIS and MT7530_P6_DIS bits of the hardware trap. Deal with
>> these bits only when the relevant port is being enabled or disabled. This
>> ensures that these ports will be disabled when they are not in use.
>>
>> Do not set MT7530_CHG_TRAP on mt7530_setup_port5() as that's already being
>> done on mt7530_setup().
>
> Multiple users reported ([1], [2]) that after I've imported the series
> to OpenWrt they noticed that WAN connection on MT7621 boards using
> PHY-muxing to hook up either port 0 or port 4 to GMAC1 no longer works.
>
> The link still seems to come up, but no data flows. I went ahead and
> confirmed the bug, then started bisecting the patches of this series,
> and ended up identifying this very patch being the culprit.
>
> I can't exclude that what ever the issue may be is caused by other
> downstream patches we have, but can confirm that removing this patch of
> your series [3] in OpenWrt fixes the issue. Please take a look and as
> the cover letter states you have tested this on some MT7621 board,
> please make sure traffic actually flows on the PHY-muxed port on that
> board after this patch is applied, and if not, please figure out why and
> repost a fixed version of this patch.
>
>
> Cheers
>
>
> Daniel
>
> [1]: https://github.com/openwrt/openwrt/issues/15273
> [2]: https://github.com/openwrt/openwrt/issues/15279
> [3]: https://git.openwrt.org/?p=openwrt/openwrt.git;a=commit;h=a8dde7e5bd6d289db6485cf57d3512ea62eaa827

Thanks for reporting this Daniel. I am not happy that I've caused all this
fuss. My testing as described on the cover letter did not include the
hardware design with PHY muxing. Lesson learned; next time, I'll make sure
to test the specific hardware design when I work on the part of the code
that would affect that hardware design.

That said, I've submitted a patch that fixes this issue [1]. I have tested
the hardware design with PHY muxing with this fix applied and I don't
experience this issue anymore.

[1] https://lore.kernel.org/netdev/20240427-for-netnext-mt7530-do-not-disable-port5-when-phy-muxing-v1-1-793cdf9d7707@arinc9.com/

Arınç