u-boot ethernet device not ready in time (3 replies)

Hi,
I try to make a netboot over tftp with statically assigned ip address. This is the configuration of bootcmd:

bootcmd=env set ipaddr 192.168.178.46; env set serverip 192.168.178.39; tftp 0x82000000 Image; tftp 0x88000000 imx.dtb;

after booting it shows following problem:

loading FDT from mmc 0 'imx8mp-qsxp-ml81-qsbase3-raspi-display.dtb'
MAC addr: 00:0c:c6:06:2d:dc
Net: eth0: ethernet@30bf0000
Hit any key to stop autoboot: 0
ethernet@30bf0000 Waiting for PHY auto negotiation to complete......... TIMEOUT !
ethernet@30bf0000: phy_startup() failed: -110
ethernet@30bf0000: eqos_start() FAILED: -110
ethernet@30bf0000 Waiting for PHY auto negotiation to complete.... done

this is as it seems because of not yet initialized ethernet device. As workaround I used a sleep 10, just in front of tftp command to give the ethernet device more time for initialization

question: is it possible to somehow programmatically test for available network device? something like if test is_eth_online then tftp ??

Thanks
Ivan