Re: [PATCH net-next 0/8] net: stmmac: improve PCS support
From: Mohd Ayaan Anwar <mohd.anwar@oss.qualcomm.com>
Date: 2026-03-15 23:46:02
Also in:
linux-arm-kernel, linux-arm-msm
Hi Russell, On Fri, Mar 13, 2026 at 12:28:30PM +0000, Russell King (Oracle) wrote:
This series is the next of the three part series sorting out the PCS support in stmmac, building on part 2: net: stmmac: qcom-ethqos: further serdes reorganisation Similar patches have been posted previously. This series does away with the common SerDes PHY support, instead using a flag to indicate whether 2500Mbps mode is supported (STMMAC_FLAG_SERDES_SUPPORTS_2500M.) At this time, I have no plans to resurect the common SerDes PHY support - the generic PHY layer implementations are just too random to consider that, and I certainly do not want the extra work of fixing that. Changes from RFC v3: - only set default_an_inband if using SGMII/2500BASE-X mode.
I encountered two NULL pointer dereferences and had to add a few workarounds to proceed with testing. 1. On QCS9100 Ride R3, the mdio subnode is only defined for ethernet0 (see lemans-ride-ethernet-aqr115c.dtsi). ethernet1 uses ethernet0's MDIO bus, so plat_dat->mdio_bus_data is NULL for ethernet1. Therefore, we get: [ 9.205979] Hardware name: Qualcomm Technologies, Inc. Lemans Ride Rev3 (DT) [ 9.221071] pc : qcom_ethqos_probe+0xc4/0x478 [dwmac_qcom_ethqos] [ 9.221078] lr : qcom_ethqos_probe+0x7c/0x478 [dwmac_qcom_ethqos] [ 9.221080] sp : ffff800081aa37f0 [ 9.221081] x29: ffff800081aa3860 x28: ffffcf84de69cfe8 x27: 0000000000000001 [ 9.221084] x26: 0000000000000000 x25: ffff0000b4577c80 x24: ffff0000818fd010 [ 9.221087] x23: ffff000ec7057628 x22: 0000000000000000 x21: ffffcf84ca2ce028 [ 9.221089] x20: ffff0000818fd000 [ 9.236975] x19: ffff0000b3301740 x18: 00000000ffffffff [ 9.236977] x17: 0000000000000000 x16: ffffcf84dc4a5448 x15: ffff0000b3301ec5 [ 9.236980] x14: 0000000000000000 x13: 0000000000000030 x12: 0101010101010101 [ 9.236982] x11: 7f7f7f7f7f7f7f7f x10: 00000000001305b0 x9 : 0000000000000000 [ 9.236984] x8 : ffff0000b3301780 x7 : 0000000000000000 x6 : 000000000000003f [ 9.236986] x5 : 0000000000000040 x4 : 0000000000000000 x3 : ffff0000818fd210 [ 9.236988] x2 : 0000000000000017 x1 : 0000000000000000 x0 : 0000000000000001 [ 9.236991] Call trace: [ 9.236991] qcom_ethqos_probe+0xc4/0x478 [dwmac_qcom_ethqos] (P) [ 9.236994] platform_probe+0x5c/0xac ... [ 9.343300] Code: 910a7000 f9400b21 f9010320 52800020 (39005420) [ 9.343302] ---[ end trace 0000000000000000 ]--- I added the following workaround: --- a/drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c @@ -765,7 +767,10 @@ static int qcom_ethqos_probe(struct platform_device *pdev) case PHY_INTERFACE_MODE_SGMII: ethqos->configure_func = ethqos_configure_sgmii; plat_dat->mac_finish = ethqos_mac_finish_serdes; - plat_dat->mdio_bus_data->default_an_inband = true; + if (plat_dat->mdio_bus_data) + plat_dat->mdio_bus_data->default_an_inband = true; + else + dev_err(dev, "plat_dat->mdio_bus_data is NULL"); break; default: dev_err(dev, "Unsupported phy mode %s\n", 2. After working around issue 1, I hit the following: [ 27.822907] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000 [ 27.831944] Mem abort info: [ 27.834832] ESR = 0x0000000086000006 [ 27.838693] EC = 0x21: IABT (current EL), IL = 32 bits [ 27.844163] SET = 0, FnV = 0 [ 27.847320] EA = 0, S1PTW = 0 [ 27.850563] FSC = 0x06: level 2 translation fault [ 27.855587] user pgtable: 4k pages, 48-bit VAs, pgdp=0000000134b1c000 [ 27.862212] [0000000000000000] pgd=080000010185c403, p4d=080000010185c403, pud=0800000134884403, pmd=0000000000000000 [ 27.873107] Internal error: Oops: 0000000086000006 [#1] SMP [ 28.001619] Hardware name: Qualcomm Technologies, Inc. Lemans Ride Rev3 (DT) [ 28.008853] pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) [ 28.016001] pc : 0x0 [ 28.018259] lr : phylink_pcs_an_restart+0x50/0x5c [ 28.023092] sp : ffff8000869fb900 ... [ 28.185967] ---[ end trace 0000000000000000 ]--- This occurs due to pl->pcs->ops->pcs_an_restart being NULL. I added the following workaround: --- a/drivers/net/phy/phylink.c +++ b/drivers/net/phy/phylink.c @@ -1026,7 +1026,8 @@ static void phylink_pcs_an_restart(struct phylink *pl) if (pl->pcs && linkmode_test_bit(ETHTOOL_LINK_MODE_Autoneg_BIT, pl->link_config.advertising) && phy_interface_mode_is_8023z(pl->link_config.interface) && - phylink_autoneg_inband(pl->act_link_an_mode)) + phylink_autoneg_inband(pl->act_link_an_mode) && + pl->pcs->ops->pcs_an_restart) pl->pcs->ops->pcs_an_restart(pl->pcs); } 3. With the recent VLAN filter changes in net-next, ndo_open takes a long time to complete as vlan_restore_hw_rx_fltr() tries to write filters for all 32 indices. This board previously timed out once, but now times out for each index. This is a separate issue unrelated to this series but I added the following workaround to rule out any timing issues. --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_vlan.c +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_vlan.c @@ -158,7 +158,8 @@ static void vlan_restore_hw_rx_fltr(struct net_device *dev, /* Extended Rx VLAN Filter Enable */ for (i = 0; i < hw->num_vlan; i++) - vlan_write_filter(dev, hw, i, hw->vlan_filter[i]); + if (hw->vlan_filter[i]) + vlan_write_filter(dev, hw, i, hw->vlan_filter[i]); } static void vlan_update_hash(struct mac_device_info *hw, u32 hash, With the above workarounds in place, 2.5G works fine, but 1G (and 100M) do not. With the RFC v1 series, only the 2.5G->1G speed change was broken. With this series, the link does not come up at 1G at all. Some observations from my failed attempt at debugging so far: - No change in behaviour after adding the provisioning code in aqr_gen4_config_init(). - Setting GMAC_AN_CTRL_RAN in dwmac_integrated_pcs_config() did not help. - After shifting to 1G, GMAC_AN_STATUS reads 0x00000008, i.e., BMSR_LSTATUS (bit 2) is clear. Sharing logs for two 1G scenarios (net-next + this series + the three workarounds above): # Booting up with a 1G link [ 8.730854] qcom-ethqos 23040000.ethernet: IRQ eth_wake_irq not found [ 8.766778] qcom-ethqos 23040000.ethernet: User ID: 0x20, Synopsys ID: 0x52 [ 8.780465] qcom-ethqos 23040000.ethernet: DWMAC4/5 [ 8.794253] qcom-ethqos 23040000.ethernet: DMA HW capability register supported [ 8.794258] qcom-ethqos 23040000.ethernet: Active PHY interface: SGMII (2) <snip> [ 8.865690] qcom-ethqos 23040000.ethernet: Using 36/40 bits DMA host/device width [ 8.865707] qcom-ethqos 23040000.ethernet: clk_csr value out of range (0xffffff00 exceeds mask 0x00000f00), truncating [ 10.860749] qcom-ethqos 23040000.ethernet eth1: Register MEM_TYPE_PAGE_POOL RxQ-0 [ 10.861119] qcom-ethqos 23040000.ethernet eth1: Register MEM_TYPE_PAGE_POOL RxQ-1 [ 10.861510] qcom-ethqos 23040000.ethernet eth1: Register MEM_TYPE_PAGE_POOL RxQ-2 [ 10.861906] qcom-ethqos 23040000.ethernet eth1: Register MEM_TYPE_PAGE_POOL RxQ-3 [ 10.871763] qcom-ethqos 23040000.ethernet eth1: Enabling Safety Features [ 10.907513] qcom-ethqos 23040000.ethernet eth1: IEEE 1588-2008 Advanced Timestamp supported [ 10.921216] qcom-ethqos 23040000.ethernet eth1: registered PTP clock [ 10.921220] qcom-ethqos 23040000.ethernet eth1: configuring for inband/2500base-x link mode [ 10.921223] qcom-ethqos 23040000.ethernet eth1: major config, requested inband/2500base-x [ 10.921226] qcom-ethqos 23040000.ethernet eth1: interface 2500base-x inband modes: pcs=01 phy=00 [ 10.921228] qcom-ethqos 23040000.ethernet eth1: major config, active inband/inband,an-disabled/2500base-x [ 10.921230] qcom-ethqos 23040000.ethernet eth1: phylink_mac_config: mode=inband/2500base-x/none adv=00000000,00000000,00008000,0000e240 pause=04 No further messages appear after this point, and the link does not come up at 1G. # Switching from 2.5G to 1G [ 8.368113] qcom-ethqos 23040000.ethernet: IRQ eth_wake_irq not found [ 8.379601] qcom-ethqos 23040000.ethernet: User ID: 0x20, Synopsys ID: 0x52 [ 8.392900] qcom-ethqos 23040000.ethernet: DWMAC4/5 [ 8.432379] qcom-ethqos 23040000.ethernet: DMA HW capability register supported <snip> [ 8.480319] qcom-ethqos 23040000.ethernet: Using 36/40 bits DMA host/device width [ 8.488609] qcom-ethqos 23040000.ethernet: clk_csr value out of range (0xffffff00 exceeds mask 0x00000f00), truncating [ 11.192140] qcom-ethqos 23040000.ethernet eth1: Register MEM_TYPE_PAGE_POOL RxQ-0 [ 11.200567] qcom-ethqos 23040000.ethernet eth1: Register MEM_TYPE_PAGE_POOL RxQ-1 [ 11.216466] qcom-ethqos 23040000.ethernet eth1: Register MEM_TYPE_PAGE_POOL RxQ-2 [ 11.232393] qcom-ethqos 23040000.ethernet eth1: Register MEM_TYPE_PAGE_POOL RxQ-3 [ 11.250011] qcom-ethqos 23040000.ethernet eth1: Enabling Safety Features [ 11.269722] qcom-ethqos 23040000.ethernet eth1: IEEE 1588-2008 Advanced Timestamp supported [ 11.286758] qcom-ethqos 23040000.ethernet eth1: registered PTP clock [ 11.300593] qcom-ethqos 23040000.ethernet eth1: configuring for inband/2500base-x link mode [ 11.300596] qcom-ethqos 23040000.ethernet eth1: major config, requested inband/2500base-x [ 11.300599] qcom-ethqos 23040000.ethernet eth1: interface 2500base-x inband modes: pcs=01 phy=00 [ 11.316311] qcom-ethqos 23040000.ethernet eth1: major config, active inband/inband,an-disabled/2500base-x [ 11.316317] qcom-ethqos 23040000.ethernet eth1: phylink_mac_config: mode=inband/2500base-x/none adv=00000000,00000000,00008000,0000e240 pause=04 [ 14.125773] qcom-ethqos 23040000.ethernet: PCS Link Up [ 14.131081] qcom-ethqos 23040000.ethernet eth1: pcs link up [ 14.147059] qcom-ethqos 23040000.ethernet eth1: Link is Up - 2.5Gbps/Full - flow control rx/tx <link speed changed to 1G> [ 25.868674] qcom-ethqos 23040000.ethernet: PCS Link Down [ 25.874184] qcom-ethqos 23040000.ethernet eth1: pcs link down [ 25.874745] qcom-ethqos 23040000.ethernet eth1: Link is Down No further messages appear after "Link is Down". I have been having some issues with the IQ9 EVK (QCA8081 PHY), so no results to report for it yet. Ayaan