From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ozlabs.ru (unknown [107.173.13.209]) by lists.ozlabs.org (Postfix) with ESMTP id 428YcJ0kPSzF37J for ; Tue, 11 Sep 2018 15:38:40 +1000 (AEST) From: Alexey Kardashevskiy To: linuxppc-dev@lists.ozlabs.org Cc: Alexey Kardashevskiy , Michael Ellerman Subject: [PATCH kernel] powerpc/powernv/ioda2: Reduce upper limit for DMA window size (retry) Date: Tue, 11 Sep 2018 15:38:05 +1000 Message-Id: <20180911053805.5345-1-aik@ozlabs.ru> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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 --- The merge commit says d3d4ffaae439 (the original of this one) was propagated but it was not: [vpl1 kernel]$ git s ce57c6610cc2:arch/powerpc/platforms/powernv/pci-ioda-tce.c | grep 'page_shift >= ' if ((level_shift - 3) * levels + page_shift >= 60) --- arch/powerpc/platforms/powernv/pci-ioda-tce.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/powerpc/platforms/powernv/pci-ioda-tce.c b/arch/powerpc/platforms/powernv/pci-ioda-tce.c index 6c5db1a..fe96910 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 */ -- 2.11.0