On Wed, 2016-02-17 at 18:26 +1100, Alexey Kardashevskiy wrote:
> Quite often drivers set only "write" permission assuming that this
> includes "read" permission as well and this works on plenty
> platforms.
> However IODA2 is strict about this and produces an EEH when "read"
> permission is not and reading happens.
>
> This adds a workaround in IODA code to always add the "read" bit when
> the "write" bit is set.
>
> This fixes breakage introduced in
> 10b35b2b74 powerpc/powernv: Do not set "read" flag if
> direction==DMA_NONE
>
> Cc: sta...@vger.kernel.org # 4.2+
Acked-by: Benjamin Herrenschmidt <b...@kernel.crashing.org>
> Signed-off-by: Alexey Kardashevskiy <a...@ozlabs.ru>
> Tested-by: Douglas Miller <dougm...@linux.vnet.ibm.com>
> ---
> arch/powerpc/platforms/powernv/pci.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/arch/powerpc/platforms/powernv/pci.c
> b/arch/powerpc/platforms/powernv/pci.c
> index 2f55c86..6a97ba4 100644
> --- a/arch/powerpc/platforms/powernv/pci.c
> +++ b/arch/powerpc/platforms/powernv/pci.c
> @@ -599,6 +599,9 @@ int pnv_tce_build(struct iommu_table *tbl, long
> index, long npages,
> u64 rpn = __pa(uaddr) >> tbl->it_page_shift;
> long i;
>
> + if (proto_tce & TCE_PCI_WRITE)
> + proto_tce |= TCE_PCI_READ;
> +
> for (i = 0; i < npages; i++) {
> unsigned long newtce = proto_tce |
> ((rpn + i) << tbl->it_page_shift);
> @@ -620,6 +623,9 @@ int pnv_tce_xchg(struct iommu_table *tbl, long
> index,
>
> BUG_ON(*hpa & ~IOMMU_PAGE_MASK(tbl));
>
> + if (newtce & TCE_PCI_WRITE)
> + newtce |= TCE_PCI_READ;
> +
> oldtce = xchg(pnv_tce(tbl, idx), cpu_to_be64(newtce));
> *hpa = be64_to_cpu(oldtce) & ~(TCE_PCI_READ |
> TCE_PCI_WRITE);
> *direction = iommu_tce_direction(oldtce);
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