From: Sinan Kaya <okaya@xxxxxxxxxxxxxx> Date: Sun, 25 Mar 2018 10:39:14 -0400 > Code includes wmb() followed by writel() in multiple places. writel() > already has a barrier on some architectures like arm64. > > This ends up CPU observing two barriers back to back before executing the > register write. > > Since code already has an explicit barrier call, changing writel() to > writel_relaxed(). > > I did a regex search for wmb() followed by writel() in each drivers > directory. > I scrubbed the ones I care about in this series. > > I considered "ease of change", "popular usage" and "performance critical > path" as the determining criteria for my filtering. > > We used relaxed API heavily on ARM for a long time but > it did not exist on other architectures. For this reason, relaxed > architectures have been paying double penalty in order to use the common > drivers. > > Now that relaxed API is present on all architectures, we can go and scrub > all drivers to see what needs to change and what can remain. > > We start with mostly used ones and hope to increase the coverage over time. > It will take a while to cover all drivers. > > Feel free to apply patches individually. > > Changes since v6: > - bring back amazon ena and add mmiowb, remove > ena_com_write_sq_doorbell_rel(). > - remove extra mmiowb in bnx2x > - correct spelling mistake in bnx2x: Replace doorbell barrier() with wmb() Series applied, thank you. -- To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
