From: Mike Rapoport <r...@linux.ibm.com> Some powerpc platforms (e.g. 85xx) limit DMA-able memory way below 4G. If a system has more physical memory than this limit, the swiotlb buffer is not addressable because it is allocated from memblock using top-down mode.
Force memblock to bottom-up mode before calling swiotlb_init() to ensure that the swiotlb buffer is DMA-able. Link: https://lkml.kernel.org/r/f1ebb706-73df-430e-9020-c214ec8ed...@xenosoft.de Reported-by: Christian Zigotzky <chzigot...@xenosoft.de> Signed-off-by: Mike Rapoport <r...@linux.ibm.com> Cc: Benjamin Herrenschmidt <b...@kernel.crashing.org> Cc: Christoph Hellwig <h...@lst.de> Cc: Darren Stevens <dar...@stevens-zone.net> Cc: mad skateman <madskate...@gmail.com> Cc: Michael Ellerman <m...@ellerman.id.au> Cc: Nicolas Saenz Julienne <nsaenzjulie...@suse.de> Cc: Paul Mackerras <pau...@samba.org> Cc: Robin Murphy <robin.mur...@arm.com> Cc: Rob Herring <robh...@kernel.org> --- arch/powerpc/mm/mem.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c index be941d382c8d..14c2c53e3f9e 100644 --- a/arch/powerpc/mm/mem.c +++ b/arch/powerpc/mm/mem.c @@ -260,6 +260,14 @@ void __init mem_init(void) BUILD_BUG_ON(MMU_PAGE_COUNT > 16); #ifdef CONFIG_SWIOTLB + /* + * Some platforms (e.g. 85xx) limit DMA-able memory way below + * 4G. We force memblock to bottom-up mode to ensure that the + * memory allocated in swiotlb_init() is DMA-able. + * As it's the last memblock allocation, no need to reset it + * back to to-down. + */ + memblock_set_bottom_up(true); swiotlb_init(0); #endif -- 2.24.0
