Fine tune the value to 21us in order to improve read/write performance.
Signed-off-by: NBen Chuang <benchuanggli@gmail.com>
Link: https://lore.kernel.org/r/20210511061835.5559-1-benchuanggli@gmail.comSigned-off-by: NUlf Hansson <ulf.hansson@linaro.org>