> > On 3/16/2018 5:05 PM, Steve Wise wrote: > >> Code includes wmb() followed by writel(). 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(). > >> > >> Signed-off-by: Sinan Kaya <okaya@xxxxxxxxxxxxxx> > > > > NAK - This isn't correct for PowerPC. For PowerPC, writeX_relaxed() is just > > writeX(). > > > > I was just looking at this with Chelsio developers, and they said the > > writeX() should be replaced with __raw_writeX(), not writeX_relaxed(), to > > get rid of the extra barrier for all architectures. > > OK. I can do that but isn't the problem at PowerPC adaptation? > > /* > * We don't do relaxed operations yet, at least not with this semantic > */ > #define readb_relaxed(addr) readb(addr) > #define readw_relaxed(addr) readw(addr) > #define readl_relaxed(addr) readl(addr) > #define readq_relaxed(addr) readq(addr) > #define writeb_relaxed(v, addr) writeb(v, addr) > #define writew_relaxed(v, addr) writew(v, addr) > #define writel_relaxed(v, addr) writel(v, addr) > #define writeq_relaxed(v, addr) writeq(v, addr) > > Why don't we fix the PowerPC's relaxed operators? Is that a bigger task? I don't know the answer, but perhaps the proper fix is to correctly implement these for PPC? > > >From API perspective both __raw_writeX() and writeX_relaxed() are > correct. > It is just PowerPC doesn't seem the follow the definition yet. -- 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
