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    SubjectRE: [PATCHv2 2/3] iovmm: add superpages support to fixed da address


    > -----Original Message-----
    > From: Felipe Contreras [mailto:felipe.contreras@gmail.com]
    > Sent: Sunday, October 10, 2010 10:22 AM
    > To: Guzman Lugo, Fernando
    > Cc: Hiroshi.DOYU@nokia.com; david.cohen@nokia.com;
    > felipe.contreras@nokia.com; ameya.palande@nokia.com;
    > linux-kernel@vger.kernel.org; andy.shevchenko@gmail.com;
    > linux-omap@vger.kernel.org
    > Subject: Re: [PATCHv2 2/3] iovmm: add superpages support to
    > fixed da address
    >
    > On Tue, Oct 5, 2010 at 12:02 AM, Fernando Guzman Lugo
    > <x0095840@ti.com> wrote:
    > > This patch adds superpages support to fixed ad address inside
    > > iommu_kmap function.
    > >
    > > Signed-off-by: Fernando Guzman Lugo <x0095840@ti.com>
    > > ---
    > >  arch/arm/plat-omap/iovmm.c |   61
    > > ++++++++++++++++++++++++++-----------------
    > >  1 files changed, 37 insertions(+), 24 deletions(-)
    > >
    > > diff --git a/arch/arm/plat-omap/iovmm.c
    > b/arch/arm/plat-omap/iovmm.c
    > > index 34f0012..8006a19 100644
    > > --- a/arch/arm/plat-omap/iovmm.c
    > > +++ b/arch/arm/plat-omap/iovmm.c
    > > @@ -87,27 +87,37 @@ static size_t sgtable_len(const struct sg_table
    > > *sgt)
    > >  }
    > >  #define sgtable_ok(x)  (!!sgtable_len(x))
    > >
    > > +
    > > +static unsigned max_alignment(u32 addr) {
    > > +       int i;
    > > +       unsigned pagesize[] = { SZ_16M, SZ_1M, SZ_64K, SZ_4K, };
    > > +       for (i = 0; i < ARRAY_SIZE(pagesize) && addr &
    > (pagesize[i] -
    > > +1); i++)
    > > +               ;
    > > +       return (i < ARRAY_SIZE(pagesize)) ? pagesize[i] : 0; }
    > > +
    > > +
    >
    > I don't think those extra spaces make sense.

    Ok, it will be fixed.

    >
    > >  /*
    > >  * calculate the optimal number sg elements from total
    > bytes based on
    > >  * iommu superpages
    > >  */
    > > -static unsigned int sgtable_nents(size_t bytes)
    > > +static unsigned int sgtable_nents(size_t bytes, u32 da, u32 pa)
    > >  {
    > > -       int i;
    > > -       unsigned int nr_entries;
    > > -       const unsigned long pagesize[] = { SZ_16M, SZ_1M, SZ_64K,
    > > SZ_4K, };
    > > +       unsigned int nr_entries = 0, ent_sz;
    >
    > How about s/unsigned int/unsigned/?

    It is exactly the same, but not problem for me.

    >
    > >
    > >        if (!IS_ALIGNED(bytes, PAGE_SIZE)) {
    > >                pr_err("%s: wrong size %08x\n", __func__, bytes);
    > >                return 0;
    > >        }
    > >
    > > -       nr_entries = 0;
    > > -       for (i = 0; i < ARRAY_SIZE(pagesize); i++) {
    > > -               if (bytes >= pagesize[i]) {
    > > -                       nr_entries += (bytes / pagesize[i]);
    > > -                       bytes %= pagesize[i];
    > > -               }
    > > +       while (bytes) {
    > > +               ent_sz = max_alignment(da | pa);
    > > +               ent_sz = min(ent_sz, (unsigned)iopgsz_max(bytes));
    > > +               nr_entries++;
    > > +               da += ent_sz;
    > > +               pa += ent_sz;
    > > +               bytes -= ent_sz;
    > >        }
    > >        BUG_ON(bytes);
    > >
    > > @@ -115,7 +125,8 @@ static unsigned int sgtable_nents(size_t bytes)
    > >  }
    > >
    > >  /* allocate and initialize sg_table header(a kind of
    > 'superblock') */
    > > -static struct sg_table *sgtable_alloc(const size_t bytes,
    > u32 flags)
    > > +static struct sg_table *sgtable_alloc(const size_t bytes,
    > u32 flags,
    > > +                                                       u32 da, u32
    > > +pa)
    > >  {
    > >        unsigned int nr_entries;
    > >        int err;
    > > @@ -127,9 +138,8 @@ static struct sg_table
    > *sgtable_alloc(const size_t
    > > bytes, u32 flags)
    > >        if (!IS_ALIGNED(bytes, PAGE_SIZE))
    > >                return ERR_PTR(-EINVAL);
    > >
    > > -       /* FIXME: IOVMF_DA_FIXED should support 'superpages' */
    > > -       if ((flags & IOVMF_LINEAR) && (flags & IOVMF_DA_ANON)) {
    > > -               nr_entries = sgtable_nents(bytes);
    > > +       if (flags & IOVMF_LINEAR) {
    > > +               nr_entries = sgtable_nents(bytes, da, pa);
    > >                if (!nr_entries)
    > >                        return ERR_PTR(-EINVAL);
    > >        } else
    > > @@ -409,7 +419,8 @@ static inline void sgtable_drain_vmalloc(struct
    > > sg_table *sgt)
    > >        BUG_ON(!sgt);
    > >  }
    > >
    > > -static void sgtable_fill_kmalloc(struct sg_table *sgt, u32
    > pa, size_t
    > > len)
    > > +static void sgtable_fill_kmalloc(struct sg_table *sgt, u32 pa, u32
    > > +da,
    > > +                                                          
    >     size_t
    > > +len)
    > >  {
    > >        unsigned int i;
    > >        struct scatterlist *sg;
    > > @@ -420,7 +431,8 @@ static void sgtable_fill_kmalloc(struct
    > sg_table
    > > *sgt, u32 pa, size_t len)
    > >        for_each_sg(sgt->sgl, sg, sgt->nents, i) {
    > >                size_t bytes;
    > >
    > > -               bytes = iopgsz_max(len);
    > > +               bytes = max_alignment(da | pa);
    > > +               bytes = min(bytes, (size_t)iopgsz_max(len));
    >
    > Why the size_t casting?

    To void this warning:
    arch/arm/plat-omap/iovmm.c:440: warning: comparison of distinct pointer types lacks a cast

    I will update with minor changes and resend.

    Thanks and regards,
    Fernando.

    >
    > Otherwise:
    > Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
    >
    > --
    > Felipe Contreras
    > --
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