From: Nicolin Chen <nicoleotsuka@gmail.com>
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
Subject: [PATCH 2/2] dma-mapping: set default segment_boundary_mask to ULONG_MAX
Date: Tue, 1 Sep 2020 15:16:46 -0700 [thread overview]
Message-ID: <20200901221646.26491-3-nicoleotsuka@gmail.com> (raw)
In-Reply-To: <20200901221646.26491-1-nicoleotsuka@gmail.com>
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 <nicoleotsuka@gmail.com>
---
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
next prev parent reply other threads:[~2020-09-01 22:17 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-01 22:16 [PATCH 0/2] dma-mapping: update default segment_boundary_mask Nicolin Chen
2020-09-01 22:16 ` [PATCH 1/2] dma-mapping: introduce dma_get_seg_boundary_nr_pages() Nicolin Chen
2020-09-03 3:47 ` Michael Ellerman
2020-09-03 10:57 ` Andy Shevchenko
2020-09-03 16:12 ` Christoph Hellwig
2020-09-03 17:53 ` Christophe Leroy
2020-09-01 22:16 ` Nicolin Chen [this message]
2020-09-02 8:13 ` [PATCH 0/2] dma-mapping: update default segment_boundary_mask Niklas Schnelle
2020-09-03 3:26 ` Nicolin Chen
2020-09-03 16:13 ` Christoph Hellwig
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