On Mon, Jan 09, 2023 at 03:41:14AM +0000, JiaJie Ho wrote: > > The average wait time is around 20 microseconds. > I measured from writel cmd to wait_for_completion done. Do you know of an upper bound? E.g., if we limit it to 40us how many requests would fail on average? Having a maximum delay of 40us would be OK with wait == 0. So you could implement it in a way such that if the wait time exceeded 40us then you return if wait == 0, otherwise you can wait longer. Cheers, -- Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt