Re: [PATCH net-next 05/14] net: ethernet: mtk_eth_soc: reduce MDIO bus access latency
From: Ilya Lipnitskiy <hidden>
Date: 2021-04-23 04:16:35
Also in:
linux-mediatek, lkml, netdev
On Thu, Apr 22, 2021 at 5:33 AM Felix Fietkau [off-list ref] wrote:
On 2021-04-22 06:09, Ilya Lipnitskiy wrote:quoted
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.
No problem, I will respin with your original change. Looks like we can't take advantage of iopoll.h routine in this case, but that's not the end of the world!
On a fully loaded system, I'd prefer to let the MDIO access take longer instead of wasting cycles on udelay. - Felix
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