On Mon, 2011-10-10 at 11:29 +0200, Eli Cohen wrote: > On Mon, Oct 10, 2011 at 11:24:05AM +0200, Benjamin Herrenschmidt wrote: > > On Mon, 2011-10-10 at 11:16 +0200, Eli Cohen wrote: > > > > > Until then I think we need to have the logic working right on ppc and > > > measure if blue flame buys us any improvement in ppc. If that's not > > > the case (e.g because write combining is not working), then maybe we > > > should avoid using blueflame in ppc. > > > Could any of the guys from IBM check this and give us feedback? > > > > I don't have the necessary hardware myself to test that but maybe Thadeu > > can. > > > > Note that for WC to work, things must be mapped non-guarded. You can do > > that by using ioremap_prot() with pgprot_noncached_wc(PAGE_KERNEL) or > > ioremap_wc() (dunno how "generic" the later is). > > I use the io mapping API: > > at driver statrt: > priv->bf_mapping = io_mapping_create_wc(bf_start, bf_len); > if (!priv->bf_mapping) > err = -ENOMEM; > > and then: > uar->bf_map = io_mapping_map_wc(priv->bf_mapping, uar->index << > PAGE_SHIFT); > > > Will this work on ppc?
That API has never been tested on ppc I suspect. We don't have CONFIG_HAVE_ATOMIC_IOMAP (mostly because we never needed it, it was designed and only ever used for Intel graphics before), so it will fallback to: static inline struct io_mapping * io_mapping_create_wc(resource_size_t base, unsigned long size) { return (struct io_mapping __force *) ioremap_wc(base, size); } Which should work (hopefully :-) Cheers, Ben. _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev