net: dwmac-rk: keep the board's own MAC when booted from SD - #525
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A Rockchip board's assigned MAC lives in vendor storage on the eMMC, as LAN_MAC. Boot the same board from an SD card and it comes up on a different, invented address instead - and a stable one, so it looks correct while not matching the sticker. Keep the board's own address in that case. The two halves read vendor storage from different places. U-Boot reads it from the device it booted from; the kernel's sdmmc_vendor_storage always reads the eMMC (every access goes through rk_emmc_transfer(), there is no SD path). Boot from eMMC and both see the same store, so the address U-Boot puts in the DT already equals LAN_MAC and nothing needs correcting - which is why the boards Rockchip ships never show this. Boot from SD and U-Boot finds no store on its boot device, invents an address with net_random_ethaddr() and passes that up, while the real one sits unread on the eMMC. On an RK3528 box the DT carried 36:c8:c4:28:e4:08 while the eMMC store held the sticker address c4:2a:fe:10:51:77. stmmac_check_ether_addr() only consults plat->get_eth_addr when the device has no valid address yet, so the invented one wins and rk_get_eth_addr() - which reads LAN_MAC exactly as Rockchip intended - never runs. Tell the two apart by the locally-administered bit: an assigned address never has it set, a generated one always does. Blank such an address so the existing path asks rk_get_eth_addr(). Keep a copy and restore it if the store turns out to hold nothing, so the board never ends up with a freshly invented address it did not have before. Vendor storage registers after this driver probes, so defer until it is up. Bound the wait by time rather than a retry count: the store is a single global resource, so one deadline is correct for every GMAC waiting on it. Keep the bound short - a board with no vendor storage pays it once at boot and then behaves exactly as before. Signed-off-by: Artem Butusov <art.sormy@gmail.com>
WalkthroughThe driver adds jiffies-based timeout tracking and storage for a bootloader-provided MAC address. MAC acquisition now uses that address before generating and persisting a random address. During probe, locally administered addresses trigger a two-second wait for Rockchip vendor storage. The probe defers while waiting and releases parsed device-tree resources. After setup, the driver retains the original address as fallback and clears the stmmac resource MAC when vendor storage is available. Estimated code review effort: 3 (Moderate) | ~20 minutes Merge Risk: 🟡 Moderate · up to The change may replace a valid locally administered, board-provisioned MAC address with another stored address, causing incorrect network identity or conflicts. Merge should wait until generated and intentionally provisioned addresses are distinguished, or the behavior is explicitly opted into. 🚥 Pre-merge checks | ✅ 5✅ Passed checks (5 passed)
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Inline comments:
In `@drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c`:
- Around line 3129-3145: Restrict the deferred vendor-storage wait and LAN_MAC
replacement logic around is_local_ether_addr and stmmac_res.mac to addresses
identified as bootloader-generated, rather than all locally administered
addresses. Add a Rockchip-specific opt-in device-tree property or preserve
MAC-source provenance, and ensure valid board-provisioned local-mac-address
values bypass this path while retaining existing retry and timeout behavior.
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drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c
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A board's assigned MAC lives in vendor storage on the eMMC as
LAN_MAC. Boot fromSD and it comes up on an invented address instead — stable, so it looks correct
while not matching the sticker.
U-Boot reads vendor storage from its boot device; the kernel always reads the eMMC
(
rk_emmc_transfer(), no SD path). Boot from eMMC and both agree, which is whyRockchip's own boards never show this.
stmmac_check_ether_addr()only callsplat->get_eth_addrwhen there is no validaddress, so the invented one wins and
rk_get_eth_addr()never runs.Blank a locally-administered address so that path runs, keeping a copy to restore
if the store holds nothing. Wait for vendor storage before anything is claimed, so
a deferred retry does not re-request resources; bounded by time.
Verified on an RK3528 box booted from SD:
end0is nowc4:2a:fe:10:51:77(thesticker), was
36:c8:c4:28:e4:08. Four reboots, probe runs once, no new dmesgerrors.