[PATCH] kernel: Mediatek: fix EEE registers init

[Jonas Gorski]

Hi,

On Sat, Mar 8, 2025 at 7:01 PM Qingfang Deng <dqfext at gmail.com> wrote:
>
> After booting, a "transmit queue 0 timed out" warning followed by a
> register dump was observed. The dump indicates that mtk_hw_init() does
> not initialize the EEECR during probe. This occurs because the
> netdev is allocated in mtk_add_mac(), which is called after
> mtk_hw_init(). Consequently, the EEECR register remains uninitialized
> until a reset is triggered, causing mtk_hw_init() to run again with a
> valid netdev, at which point the register is finally set.
>
> To address this, instead of modifying the probe sequence, latch the Tx
> LPI enable state and timer value, and move the EEECR register
> initialization to mtk_mac_link_up() to ensure proper setup when the
> interface comes up.
>
> Additionally, the splat reveals that LPI functionality is controlled by
> the MAC_MCR_EEE bits in the MCR register. Update mtk_set_eee() to
> modify these bits accordingly.
>
> Fixes: d8315d5358d5 ("kernel: backport Mediatek SoC EEE support")
> Fixes: edddbaf79ccf ("kernel: Mediatek: set default EEE Tx LPI timer")
> Signed-off-by: Qingfang Deng <dqfext at gmail.com>
> ---
>  ...et-ethernet-mediatek-add-EEE-support.patch | 57 ++++++++++++-------
>  ..._eth_soc-add-hw-dump-for-forced-rese.patch |  4 +-
>  ...net-mtk_eth_soc-enable-threaded-NAPI.patch |  2 +-
>  ..._eth_soc-reset-all-TX-queues-on-DMA-.patch |  2 +-
>  ..._eth_soc-compile-out-netsys-v2-code-.patch |  4 +-
>  ..._eth_soc-work-around-issue-with-send.patch |  6 +-
>  ...ernet-mtk_eth_soc-use-napi_build_skb.patch |  4 +-
>  ...-mediatek-enlarge-DMA-reserve-buffer.patch |  2 +-
>  ..._eth_soc-fix-memory-corruption-durin.patch |  2 +-
>  ..._eth_soc-add-paths-and-SerDes-modes-.patch | 26 ++++-----
>  ...th_soc-reduce-rx-ring-size-for-older.patch | 16 +++---
>  ..._eth_soc-do-not-enable-page-pool-sta.patch |  4 +-
>  12 files changed, 71 insertions(+), 58 deletions(-)
>
> diff --git a/target/linux/generic/backport-6.6/753-v6.15-net-ethernet-mediatek-add-EEE-support.patch b/target/linux/generic/backport-6.6/753-v6.15-net-ethernet-mediatek-add-EEE-support.patch
> index d9b86ae36e..b908d133b5 100644
> --- a/target/linux/generic/backport-6.6/753-v6.15-net-ethernet-mediatek-add-EEE-support.patch
> +++ b/target/linux/generic/backport-6.6/753-v6.15-net-ethernet-mediatek-add-EEE-support.patch
> @@ -23,34 +23,23 @@ Signed-off-by: Qingfang Deng <dqfext at gmail.com>
>                  MAC_MCR_FORCE_DPX | MAC_MCR_FORCE_TX_FC |
>                  MAC_MCR_FORCE_RX_FC);
>
> -@@ -811,6 +812,18 @@ static void mtk_mac_link_up(struct phyli
> +@@ -811,6 +812,15 @@ static void mtk_mac_link_up(struct phyli
>         if (rx_pause)
>                 mcr |= MAC_MCR_FORCE_RX_FC;
>
> -+      if (mode == MLO_AN_PHY && phy && phy_init_eee(phy, false) >= 0) {
> -+              switch (speed) {
> -+              case SPEED_2500:
> -+              case SPEED_1000:
> -+                      mcr |= MAC_MCR_EEE1G;
> -+                      break;
> -+              case SPEED_100:
> -+                      mcr |= MAC_MCR_EEE100M;
> -+                      break;
> -+              }
> ++      if (mode == MLO_AN_PHY && phy && mac->tx_lpi_enabled && phy_init_eee(phy, false) >= 0) {
> ++              mcr |= MAC_MCR_EEE100M | MAC_MCR_EEE1G;
> ++              mtk_w32(mac->hw,
> ++                      FIELD_PREP(MAC_EEE_WAKEUP_TIME_1000, 17) |
> ++                      FIELD_PREP(MAC_EEE_WAKEUP_TIME_100, 36) |
> ++                      FIELD_PREP(MAC_EEE_LPI_TXIDLE_THD, mac->txidle_thd_ms),
> ++                      MTK_MAC_EEECR(mac->id));
>  +      }
>  +

Please don't modify backported patches, they represent upstream
accepted changes, so they are immutable in that regard (apart from
required changes for adapting them to older kernels).

Just add a patch on top that fixes the behavior, and ideally also send
it  upstream to netdev so it gets proper review etc.

Best Regards,
Jonas