Re: [PATCH net-next 05/14] net: ethernet: mtk_eth_soc: reduce MDIO bus access latency

On 2021-04-22 06:09, Ilya Lipnitskiy wrote:

From: Felix Fietkau <nbd@nbd.name>

usleep_range often ends up sleeping much longer than the 10-20us provided
as a range here. This causes significant latency in mdio bus acceses,
which easily adds multiple seconds to the boot time on MT7621 when polling
DSA slave ports.

Use udelay via readx_poll_timeout_atomic, since the MDIO access does not
take much time

Signed-off-by: Felix Fietkau <nbd@nbd.name>
[Ilya: use readx_poll_timeout_atomic instead of cond_resched]

I still prefer the cond_resched() variant. On a fully loaded system, I'd
prefer to let the MDIO access take longer instead of wasting cycles on
udelay.

- Felix