From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nicolin Chen Date: Tue, 01 Sep 2020 22:16:46 +0000 Subject: [PATCH 2/2] dma-mapping: set default segment_boundary_mask to ULONG_MAX Message-Id: <20200901221646.26491-3-nicoleotsuka@gmail.com> List-Id: References: <20200901221646.26491-1-nicoleotsuka@gmail.com> In-Reply-To: <20200901221646.26491-1-nicoleotsuka@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: hch@lst.de Cc: sfr@canb.auug.org.au, mpe@ellerman.id.au, benh@kernel.crashing.org, paulus@samba.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, rth@twiddle.net, ink@jurassic.park.msu.ru, mattst88@gmail.com, linux-alpha@vger.kernel.org, tony.luck@intel.com, fenghua.yu@intel.com, linux-ia64@vger.kernel.org, schnelle@linux.ibm.com, gerald.schaefer@linux.ibm.com, hca@linux.ibm.com, gor@linux.ibm.com, borntraeger@de.ibm.com, linux-s390@vger.kernel.org, davem@davemloft.net, sparclinux@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, James.Bottomley@HansenPartnership.com, deller@gmx.de, linux-parisc@vger.kernel.org The default segment_boundary_mask was set to DMA_BIT_MAKS(32) a decade ago by referencing SCSI/block subsystem, as a 32-bit mask was good enough for most of the devices. Now more and more drivers set dma_masks above DMA_BIT_MAKS(32) while only a handful of them call dma_set_seg_boundary(). This means that most drivers have a 4GB segmention boundary because DMA API returns a 32-bit default value, though they might not really have such a limit. The default segment_boundary_mask should mean "no limit" since the device doesn't explicitly set the mask. But a 32-bit mask certainly limits those devices capable of 32+ bits addressing. So this patch sets default segment_boundary_mask to ULONG_MAX. Signed-off-by: Nicolin Chen --- include/linux/dma-mapping.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h index faab0a8210b9..df0bff2ea750 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h @@ -629,7 +629,7 @@ static inline unsigned long dma_get_seg_boundary(struct device *dev) { if (dev->dma_parms && dev->dma_parms->segment_boundary_mask) return dev->dma_parms->segment_boundary_mask; - return DMA_BIT_MASK(32); + return ULONG_MAX; } /** -- 2.17.1