t4_mdio_rd(9)

💅 t4_mdio_rd(9) — the Kernel API Manual, bestie edition ✨

Okay so we're in the Kernel API Manual today and the star of the show is t4_mdio_rd(9). Sit down, grab a strawberry drink 🍓, because reading PHY registers is about to be your new fave thing.

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🌸 NAME 🌸

t4_mdio_rd — read a PHY register through MDIO 🫶

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✨ SYNOPSIS ✨

int t4_mdio_rd (struct adapter *adap , unsigned int mbox , unsigned int
phy_addr , unsigned int mmd , unsigned int reg , u16 *valp );

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🎀 ARGUMENTS 🎀

• adap — the adapter. like, the actual NIC we're talking to, she's the main character 👑
• mbox — the mailbox to use for the FW command. that's the lil channel we shout through 📬
• phy_addr — the PHY address. which PHY we're visiting 🏠
• mmd — the PHY MMD to access, and heads up: 0 for clause 22 PHYs. write that down bestie ✍️
• reg — the register to read. the specific little slot we're peeking at 🔍
• valp — where to store the value. the cutie pointer that receives the answer 💖

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🦋 DESCRIPTION 🦋

So what does she do? She issues a FW command through the given mailbox to read a PHY register. That's it, that's the whole vibe. firmware does the heavy lifting, you get your register value back, everyone slays. 💅

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🌈 SEE ALSO 🌈

First up, the kernel file herself: ./drivers/net/ethernet/chelsio/cxgb4/t4_hw.c — go say hi 🧚

And now the whole friend group, no cap, every single one:

t4_wait_op_done_val(9), t4_set_reg_field(9), t4_read_indirect(9), t4_write_indirect(9), t4_record_mbox(9), t4_wr_mbox_meat_timeout(9), t4_memory_rw_init(9), t4_memory_update_win(9), t4_memory_rw_residual(9), t4_memory_rw(9), t4_get_regs_len(9), t4_get_regs(9), t4_eeprom_ptov(9), t4_seeprom_wp(9), t4_get_raw_vpd_params(9), t4_get_vpd_params(9), t4_get_pfres(9), sf1_read(9), sf1_write(9), flash_wait_op(9), t4_read_flash(9), t4_write_flash(9), t4_get_fw_version(9), t4_get_bs_version(9), t4_get_tp_version(9), t4_get_exprom_version(9), t4_get_vpd_version(9), t4_get_scfg_version(9), t4_get_version_info(9), t4_dump_version_info(9), t4_check_fw_version(9), t4_flash_erase_sectors(9), t4_flash_cfg_addr(9), t4_load_fw(9), t4_phy_fw_ver(9), t4_load_phy_fw(9), t4_fwcache(9), fwcaps16_to_caps32(9), fwcaps32_to_caps16(9), t4_link_acaps(9), t4_link_l1cfg_core(9), t4_restart_aneg(9), t4_handle_intr_status(9), t4_slow_intr_handler(9), t4_intr_enable(9), t4_intr_disable(9), t4_config_rss_range(9), t4_config_glbl_rss(9), t4_config_vi_rss(9), t4_read_rss(9), t4_tp_fw_ldst_rw(9), t4_tp_indirect_rw(9), t4_tp_pio_read(9), t4_tp_pio_write(9), t4_tp_tm_pio_read(9), t4_tp_mib_read(9), t4_read_rss_key(9), t4_write_rss_key(9), t4_read_rss_pf_config(9), t4_read_rss_vf_config(9), t4_read_rss_pf_map(9), t4_read_rss_pf_mask(9), t4_tp_get_tcp_stats(9), t4_tp_get_err_stats(9), t4_tp_get_cpl_stats(9), t4_tp_get_rdma_stats(9), t4_get_fcoe_stats(9), t4_get_usm_stats(9), t4_read_mtu_tbl(9), t4_read_cong_tbl(9), t4_tp_wr_bits_indirect(9), init_cong_ctrl(9), t4_load_mtus(9), t4_get_chan_txrate(9), t4_set_trace_filter(9), t4_get_trace_filter(9), t4_pmtx_get_stats(9), t4_pmrx_get_stats(9), compute_mps_bg_map(9), t4_get_mps_bg_map(9), t4_get_tp_e2c_map(9), t4_get_tp_ch_map(9), t4_get_port_type_description(9), t4_get_port_stats_offset(9), t4_get_port_stats(9), t4_get_lb_stats(9), t4_mdio_wr(9), t4_sge_decode_idma_state(9), t4_sge_ctxt_flush(9), t4_read_sge_dbqtimers(9), t4_fw_hello(9), t4_fw_bye(9), t4_early_init(9), t4_fw_reset(9), t4_fw_halt(9), t4_fw_restart(9), t4_fw_upgrade(9), t4_fl_pkt_align(9), t4_fixup_host_params(9), t4_fw_initialize(9), t4_query_params_rw(9), t4_set_params_timeout(9), t4_set_params(9), t4_cfg_pfvf(9), t4_alloc_vi(9), t4_free_vi(9), t4_set_rxmode(9), t4_free_encap_mac_filt(9), t4_free_raw_mac_filt(9), t4_alloc_encap_mac_filt(9), t4_alloc_raw_mac_filt(9), t4_alloc_mac_filt(9), t4_free_mac_filt(9), t4_change_mac(9), t4_set_addr_hash(9), t4_enable_vi_params(9), t4_enable_vi(9), t4_enable_pi_params(9), t4_identify_port(9), t4_iq_stop(9), t4_iq_free(9), t4_eth_eq_free(9), t4_ctrl_eq_free(9), t4_ofld_eq_free(9), t4_link_down_rc_str(9), fwcap_to_fwspeed(9), lstatus_to_fwcap(9), t4_handle_get_port_info(9), t4_update_port_info(9), t4_get_link_params(9), t4_handle_fw_rpl(9), init_link_config(9), t4_prep_adapter(9), t4_shutdown_adapter(9), t4_bar2_sge_qregs(9), t4_init_devlog_params(9), t4_init_sge_params(9), t4_init_tp_params(9), t4_filter_field_shift(9), t4_init_portinfo(9), t4_read_cimq_cfg(9), t4_read_cim_ibq(9), t4_read_cim_obq(9), t4_cim_read(9), t4_cim_write(9), t4_cim_read_la(9), t4_tp_read_la(9), t4_idma_monitor_init(9), t4_idma_monitor(9), t4_load_cfg(9), t4_set_vf_mac_acl(9), t4_read_pace_tbl(9), t4_get_tx_sched(9), t4_sge_ctxt_rd_bd(9), t4_i2c_rd(9), t4_set_vlan_acl(9), modify_device_id(9), t4_load_boot(9), t4_flash_bootcfg_addr(9)

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ngl the SEE ALSO section is giving full group chat at 2am and I love that for her 💀

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Okay that's the whole page, you ate that 🍓✨ mwah 💋 — this lil number comes from <pink>./drivers/net/ethernet/chelsio...</pink> and she's stamped October 2026, so go forth and read those PHY registers, bestie. periodt. 💜🌷