From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Nishanth Aravamudan <nacc@linux.vnet.ibm.com>
Cc: Matthew Wilcox <willy@linux.intel.com>,
Keith Busch <keith.busch@intel.com>,
Paul Mackerras <paulus@samba.org>,
Michael Ellerman <mpe@ellerman.id.au>,
Alexey Kardashevskiy <aik@ozlabs.ru>,
David Gibson <david@gibson.dropbear.id.au>,
Christoph Hellwig <hch@infradead.org>,
linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH 0/5 v2] Fix NVMe driver support on Power with 32-bit DMA
Date: Sat, 03 Oct 2015 07:35:09 +1000 [thread overview]
Message-ID: <1443821709.27295.20.camel@kernel.crashing.org> (raw)
In-Reply-To: <20151002210435.GM8040@linux.vnet.ibm.com>
On Fri, 2015-10-02 at 14:04 -0700, Nishanth Aravamudan wrote:
> Right, I did start with your advice and tried that approach, but it
> turned out I was wrong about the actual issue at the time. The problem
> for NVMe isn't actually the starting address alignment (which it can
> handle not being aligned to the device's page size). It doesn't handle
> (addr + len % dev_page_size != 0). That is, it's really a length
> alignment issue.
>
> It seems incredibly device specific to have a an API into the DMA code
> to request an end alignment -- no other device seems to have this
> issue/design. If you think that's better, I can fiddle with that
> instead.
>
> Sorry, I should have called this out better as an alternative
> consideration.
Nah it's fine. Ok. Also adding the alignment requirement to the API
would have been a much more complex patch since it would have had to
be implemented for all archs.
I think your current solution is fine.
Cheers,
Ben.
WARNING: multiple messages have this Message-ID (diff)
From: benh@kernel.crashing.org (Benjamin Herrenschmidt)
Subject: [PATCH 0/5 v2] Fix NVMe driver support on Power with 32-bit DMA
Date: Sat, 03 Oct 2015 07:35:09 +1000 [thread overview]
Message-ID: <1443821709.27295.20.camel@kernel.crashing.org> (raw)
In-Reply-To: <20151002210435.GM8040@linux.vnet.ibm.com>
On Fri, 2015-10-02@14:04 -0700, Nishanth Aravamudan wrote:
> Right, I did start with your advice and tried that approach, but it
> turned out I was wrong about the actual issue at the time. The problem
> for NVMe isn't actually the starting address alignment (which it can
> handle not being aligned to the device's page size). It doesn't handle
> (addr + len % dev_page_size != 0). That is, it's really a length
> alignment issue.
>
> It seems incredibly device specific to have a an API into the DMA code
> to request an end alignment -- no other device seems to have this
> issue/design. If you think that's better, I can fiddle with that
> instead.
>
> Sorry, I should have called this out better as an alternative
> consideration.
Nah it's fine. Ok. Also adding the alignment requirement to the API
would have been a much more complex patch since it would have had to
be implemented for all archs.
I think your current solution is fine.
Cheers,
Ben.
next prev parent reply other threads:[~2015-10-02 21:37 UTC|newest]
Thread overview: 88+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-02 17:16 [PATCH 0/2] Fix NVMe driver support on Power with 32-bit DMA Nishanth Aravamudan
2015-10-02 17:16 ` Nishanth Aravamudan
2015-10-02 17:18 ` [PATCH 1/2] powerpc/iommu: expose IOMMU page shift Nishanth Aravamudan
2015-10-02 17:18 ` Nishanth Aravamudan
2015-10-02 17:23 ` [PATCH 2/2] drivers/nvme: default to the IOMMU page size on Power Nishanth Aravamudan
2015-10-02 17:23 ` Nishanth Aravamudan
2015-10-02 17:25 ` Christoph Hellwig
2015-10-02 17:25 ` Christoph Hellwig
2015-10-02 17:39 ` Nishanth Aravamudan
2015-10-02 17:39 ` Nishanth Aravamudan
2015-10-02 17:41 ` Christoph Hellwig
2015-10-02 17:41 ` Christoph Hellwig
2015-10-02 18:57 ` kbuild test robot
2015-10-02 18:57 ` kbuild test robot
2015-10-06 3:19 ` [PATCH 1/2] powerpc/iommu: expose IOMMU page shift David Gibson
2015-10-06 3:19 ` David Gibson
2015-10-12 16:03 ` Nishanth Aravamudan
2015-10-12 16:03 ` Nishanth Aravamudan
2015-10-12 21:10 ` Nishanth Aravamudan
2015-10-12 21:10 ` Nishanth Aravamudan
2015-10-02 20:09 ` [PATCH 0/5 v2] Fix NVMe driver support on Power with 32-bit DMA Nishanth Aravamudan
2015-10-02 20:09 ` Nishanth Aravamudan
2015-10-02 20:11 ` [PATCH 1/5 v2] dma-mapping: add generic dma_get_page_shift API Nishanth Aravamudan
2015-10-02 20:11 ` Nishanth Aravamudan
2015-10-02 20:16 ` [PATCH 2/5 v2] powerpc/dma-mapping: override dma_get_page_shift Nishanth Aravamudan
2015-10-02 20:16 ` Nishanth Aravamudan
2015-10-02 20:19 ` [PATCH 3/5 v2] powerpc/dma: implement per-platform dma_get_page_shift Nishanth Aravamudan
2015-10-02 20:19 ` Nishanth Aravamudan
2015-10-02 20:21 ` [PATCH 4/5 v2] pseries/iommu: implement DDW-aware dma_get_page_shift Nishanth Aravamudan
2015-10-02 20:21 ` Nishanth Aravamudan
2015-10-02 20:30 ` [PATCH 5/5 v2] drivers/nvme: default to the IOMMU page size Nishanth Aravamudan
2015-10-02 20:30 ` Nishanth Aravamudan
2015-10-02 20:43 ` kbuild test robot
2015-10-02 20:43 ` kbuild test robot
2015-10-02 20:33 ` [PATCH 4/5 v2] pseries/iommu: implement DDW-aware dma_get_page_shift kbuild test robot
2015-10-02 20:33 ` kbuild test robot
2015-10-06 3:39 ` Michael Ellerman
2015-10-06 3:39 ` Michael Ellerman
2015-10-07 13:56 ` [kbuild-all] " Fengguang Wu
2015-10-07 13:56 ` Fengguang Wu
2015-10-08 0:11 ` Michael Ellerman
2015-10-08 0:11 ` Michael Ellerman
2015-10-08 0:11 ` Michael Ellerman
2015-10-08 1:06 ` Fengguang Wu
2015-10-08 1:06 ` Fengguang Wu
2015-10-08 1:16 ` Fengguang Wu
2015-10-08 1:16 ` Fengguang Wu
2015-10-08 4:06 ` Michael Ellerman
2015-10-08 4:06 ` Michael Ellerman
2015-10-08 4:06 ` Michael Ellerman
2015-10-11 14:22 ` Fengguang Wu
2015-10-11 14:22 ` Fengguang Wu
2015-10-12 2:51 ` Michael Ellerman
2015-10-12 2:51 ` Michael Ellerman
2015-10-12 2:51 ` Michael Ellerman
2015-10-08 7:46 ` Christoph Hellwig
2015-10-08 7:46 ` Christoph Hellwig
2015-10-11 14:19 ` testing email patches Fengguang Wu
2015-10-11 14:19 ` Fengguang Wu
2015-10-06 3:43 ` [PATCH 1/5 v2] dma-mapping: add generic dma_get_page_shift API Michael Ellerman
2015-10-06 3:43 ` Michael Ellerman
2015-10-06 3:43 ` Michael Ellerman
2015-10-06 9:51 ` Christoph Hellwig
2015-10-06 9:51 ` Christoph Hellwig
2015-10-12 16:04 ` Nishanth Aravamudan
2015-10-12 16:04 ` Nishanth Aravamudan
2015-10-12 21:06 ` Nishanth Aravamudan
2015-10-12 21:06 ` Nishanth Aravamudan
2015-10-14 15:39 ` Nishanth Aravamudan
2015-10-14 15:39 ` Nishanth Aravamudan
2015-10-14 15:42 ` Christoph Hellwig
2015-10-14 15:42 ` Christoph Hellwig
2015-10-15 22:52 ` Nishanth Aravamudan
2015-10-15 22:52 ` Nishanth Aravamudan
2015-10-15 22:52 ` Nishanth Aravamudan
2015-10-19 17:56 ` Nishanth Aravamudan
2015-10-19 17:56 ` Nishanth Aravamudan
2015-10-19 17:56 ` Nishanth Aravamudan
2015-10-02 20:51 ` [PATCH 0/5 v2] Fix NVMe driver support on Power with 32-bit DMA Benjamin Herrenschmidt
2015-10-02 20:51 ` Benjamin Herrenschmidt
2015-10-02 21:04 ` Nishanth Aravamudan
2015-10-02 21:04 ` Nishanth Aravamudan
2015-10-02 21:35 ` Benjamin Herrenschmidt [this message]
2015-10-02 21:35 ` Benjamin Herrenschmidt
2015-10-02 21:48 ` Nishanth Aravamudan
2015-10-02 21:48 ` Nishanth Aravamudan
2015-10-03 8:19 ` Christoph Hellwig
2015-10-03 8:19 ` Christoph Hellwig
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