From: Alexey Kardashevskiy Date: Tue, 11 Sep 2018 05:38:05 +0000 (+1000) Subject: powerpc/powernv/ioda2: Reduce upper limit for DMA window size (again) X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=7233b8cab39014620ac9534da11f0f3e506d8fd8;p=openwrt%2Fstaging%2Fblogic.git powerpc/powernv/ioda2: Reduce upper limit for DMA window size (again) mpe: This was fixed originally in commit d3d4ffaae439 ("powerpc/powernv/ioda2: Reduce upper limit for DMA window size"), but contrary to what the merge commit says was inadvertently lost by me in commit ce57c6610cc2 ("Merge branch 'topic/ppc-kvm' into next") which brought in changes that moved the code to a new file. So reapply it to the new file. Original commit message follows: 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: ce57c6610cc2 ("Merge branch 'topic/ppc-kvm' into next") Signed-off-by: Alexey Kardashevskiy Signed-off-by: Michael Ellerman --- diff --git a/arch/powerpc/platforms/powernv/pci-ioda-tce.c b/arch/powerpc/platforms/powernv/pci-ioda-tce.c index 6c5db1acbe8d..fe9691040f54 100644 --- a/arch/powerpc/platforms/powernv/pci-ioda-tce.c +++ b/arch/powerpc/platforms/powernv/pci-ioda-tce.c @@ -276,7 +276,7 @@ long pnv_pci_ioda2_table_alloc_pages(int nid, __u64 bus_offset, level_shift = entries_shift + 3; level_shift = max_t(unsigned int, 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 */