6.6-stable review patch. If anyone has any objections, please let me know.
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From: Quentin Schulz quentin.schulz@cherry.de
[ Upstream commit eb7fd7aa35bfcc1e1fda4ecc42ccfcb526cdc780 ]
bus_id is currently derived from the ethernetX alias. If one is missing for the device, 0 is used. If ethernet0 points to another stmmac device or if there are 2+ stmmac devices without an ethernet alias, then bus_id will be 0 for all of those.
This is an issue because the bus_id is used to generate the mdio bus id (new_bus->id in drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c stmmac_mdio_register) and this needs to be unique.
This allows to avoid needing to define ethernet aliases for devices with multiple stmmac controllers (such as the Rockchip RK3588) for multiple stmmac devices to probe properly.
Obviously, the bus_id isn't guaranteed to be stable across reboots if no alias is set for the device but that is easily fixed by simply adding an alias if this is desired.
Fixes: 25c83b5c2e82 ("dt:net:stmmac: Add support to dwmac version 3.610 and 3.710") Signed-off-by: Quentin Schulz quentin.schulz@cherry.de Reviewed-by: Maxime Chevallier maxime.chevallier@bootlin.com Link: https://patch.msgid.link/20250527-stmmac-mdio-bus_id-v2-1-a5ca78454e3c@cherr... Signed-off-by: Paolo Abeni pabeni@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c index 4d570efd9d4bb..6c684f6ee84be 100644 --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c @@ -419,6 +419,7 @@ stmmac_probe_config_dt(struct platform_device *pdev, u8 *mac) struct device_node *np = pdev->dev.of_node; struct plat_stmmacenet_data *plat; struct stmmac_dma_cfg *dma_cfg; + static int bus_id = -ENODEV; int phy_mode; void *ret; int rc; @@ -454,8 +455,14 @@ stmmac_probe_config_dt(struct platform_device *pdev, u8 *mac) of_property_read_u32(np, "max-speed", &plat->max_speed);
plat->bus_id = of_alias_get_id(np, "ethernet"); - if (plat->bus_id < 0) - plat->bus_id = 0; + if (plat->bus_id < 0) { + if (bus_id < 0) + bus_id = of_alias_get_highest_id("ethernet"); + /* No ethernet alias found, init at -1 so first bus_id is 0 */ + if (bus_id < 0) + bus_id = -1; + plat->bus_id = ++bus_id; + }
/* Default to phy auto-detection */ plat->phy_addr = -1;