target/linux/generic/backport-5.15/704-14-v5.19-net-mtk_eth_soc-add-fixme-comment-for-state-speed-us.patch

   1 From 650a49bc65df6b0e0051a8f62d7c22d95a8f350d Mon Sep 17 00:00:00 2001
   2 From: "Russell King (Oracle)" <rmk+kernel@armlinux.org.uk>
   3 Date: Wed, 18 May 2022 15:55:07 +0100
   4 Subject: [PATCH 08/12] net: mtk_eth_soc: add fixme comment for state->speed
   5  use
   6
   7 Add a fixme comment for the last remaining incorrect usage of
   8 state->speed in the mac_config() method, which is strangely in a code
   9 path which is only run when the PHY interface mode changes.
  10
  11 This means if we are in RGMII mode, changes in state->speed will not
  12 cause the INTF_MODE, TRGMII_RCK_CTRL and TRGMII_TCK_CTRL registers to
  13 be set according to the speed, nor will the TRGPLL clock be set to the
  14 correct value.
  15
  16 Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
  17 Signed-off-by: Jakub Kicinski <kuba@kernel.org>
  18 ---
  19  drivers/net/ethernet/mediatek/mtk_eth_soc.c | 8 ++++++++
  20  1 file changed, 8 insertions(+)
  21
  22 --- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
  23 +++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
  24 @@ -374,6 +374,14 @@ static void mtk_mac_config(struct phylin
  25                                                               state->interface))
  26                                         goto err_phy;
  27                         } else {
  28 +                               /* FIXME: this is incorrect. Not only does it
  29 +                                * use state->speed (which is not guaranteed
  30 +                                * to be correct) but it also makes use of it
  31 +                                * in a code path that will only be reachable
  32 +                                * when the PHY interface mode changes, not
  33 +                                * when the speed changes. Consequently, RGMII
  34 +                                * is probably broken.
  35 +                                */
  36                                 mtk_gmac0_rgmii_adjust(mac->hw,
  37                                                        state->interface,
  38                                                        state->speed);