From: Alexey Kardashevskiy <a...@ozlabs.ru>
[ Upstream commit d3d4ffaae439981e1e441ebb125aa3588627c5d8 ]
We use PHB in mode1 which uses bit 59 to select a correct DMA window.
However there is mode2 which uses bits 59:55 and allows up to 32 DMA
windows per a PE.
Even though documentation does not clearly specify that, it seems that
the actual hardware does not support bits 59:55 even in mode1, in other
words we can create a window as big as 1<<58 but DMA simply won't work.
This reduces the upper limit from 59 to 55 bits to let the userspace know
about the hardware limits.
Fixes: 7aafac11e3 "powerpc/powernv/ioda2: Gracefully fail if too many TCE
levels requested"
Signed-off-by: Alexey Kardashevskiy <a...@ozlabs.ru>
Signed-off-by: Michael Ellerman <m...@ellerman.id.au>
Signed-off-by: Sasha Levin <alexander.le...@microsoft.com>
---
arch/powerpc/platforms/powernv/pci-ioda.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c
b/arch/powerpc/platforms/powernv/pci-ioda.c
index f52cc6fd4290..8015e40bc7ee 100644
--- a/arch/powerpc/platforms/powernv/pci-ioda.c
+++ b/arch/powerpc/platforms/powernv/pci-ioda.c
@@ -2623,7 +2623,7 @@ static long pnv_pci_ioda2_table_alloc_pages(int nid,
__u64 bus_offset,
level_shift = entries_shift + 3;
level_shift = max_t(unsigned, level_shift, PAGE_SHIFT);
- if ((level_shift - 3) * levels + page_shift >= 60)
+ if ((level_shift - 3) * levels + page_shift >= 55)
return -EINVAL;
/* Allocate TCE table */
--
2.17.1
