From: Christoph Hellwig <hch@lst.de>
To: Robin Murphy <robin.murphy@arm.com>
Cc: Christoph Hellwig <hch@lst.de>,
Nicolin Chen <nicoleotsuka@gmail.com>,
m.szyprowski@samsung.com, vdumpa@nvidia.com,
linux@armlinux.org.uk, catalin.marinas@arm.com,
will.deacon@arm.com, chris@zankel.net, jcmvbkbc@gmail.com,
joro@8bytes.org, dwmw2@infradead.org, tony@atomide.com,
akpm@linux-foundation.org, sfr@canb.auug.org.au,
treding@nvidia.com, keescook@chromium.org,
iamjoonsoo.kim@lge.com, wsa+renesas@sang-engineering.com,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-xtensa@linux-xtensa.org,
iommu@lists.linux-foundation.org
Subject: Re: [RFC/RFT PATCH 1/2] dma-contiguous: Simplify dma_*_from_contiguous() function calls
Date: Tue, 30 Apr 2019 17:18:33 +0200 [thread overview]
Message-ID: <20190430151833.GB25447@lst.de> (raw)
In-Reply-To: <0e3e6d8b-de44-d23e-a039-8d11b578ec5c@arm.com>
On Tue, Apr 30, 2019 at 01:37:54PM +0100, Robin Murphy wrote:
> On 30/04/2019 11:56, Christoph Hellwig wrote:
>> So while I really, really like this cleanup it turns out it isn't
>> actually safe for arm :( arm remaps the CMA allocation in place
>> instead of using a new mapping, which can be done because they don't
>> share PMDs with the kernel.
>>
>> So we'll probably need a __dma_alloc_from_contiguous version with
>> an additional bool fallback argument - everyone but arms uses
>> dma_alloc_from_contiguous as in your patch, just arm will get the
>> non-fallback one.
>
> Or we even just implement dma_{alloc,free}_contiguous() as a wrapper around
> the existing APIs so that users can be thoroughly checked and converted
> one-by-one.
Yeah. Actually given all the contention I wonder if the easiest solution
for now is to just open code the cma_alloc/cma_free calls in dma-direct
and dma-iommu, with the hopes that everyone is going to migrate to those
implementations in the mid-term anyway and dma_alloc_from_contiguous /
dma_release_from_contiguous just go away..
WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: Robin Murphy <robin.murphy@arm.com>
Cc: tony@atomide.com, catalin.marinas@arm.com, will.deacon@arm.com,
jcmvbkbc@gmail.com, Christoph Hellwig <hch@lst.de>,
sfr@canb.auug.org.au, linux@armlinux.org.uk, treding@nvidia.com,
linux-xtensa@linux-xtensa.org, keescook@chromium.org,
Nicolin Chen <nicoleotsuka@gmail.com>,
akpm@linux-foundation.org, linux-arm-kernel@lists.infradead.org,
chris@zankel.net, wsa+renesas@sang-engineering.com,
linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
iamjoonsoo.kim@lge.com, dwmw2@infradead.org
Subject: Re: [RFC/RFT PATCH 1/2] dma-contiguous: Simplify dma_*_from_contiguous() function calls
Date: Tue, 30 Apr 2019 17:18:33 +0200 [thread overview]
Message-ID: <20190430151833.GB25447@lst.de> (raw)
Message-ID: <20190430151833.ZW1mJxB7WMaJDsi9Nqc4CDttqg5lizvv2YPYdJOlGTU@z> (raw)
In-Reply-To: <0e3e6d8b-de44-d23e-a039-8d11b578ec5c@arm.com>
On Tue, Apr 30, 2019 at 01:37:54PM +0100, Robin Murphy wrote:
> On 30/04/2019 11:56, Christoph Hellwig wrote:
>> So while I really, really like this cleanup it turns out it isn't
>> actually safe for arm :( arm remaps the CMA allocation in place
>> instead of using a new mapping, which can be done because they don't
>> share PMDs with the kernel.
>>
>> So we'll probably need a __dma_alloc_from_contiguous version with
>> an additional bool fallback argument - everyone but arms uses
>> dma_alloc_from_contiguous as in your patch, just arm will get the
>> non-fallback one.
>
> Or we even just implement dma_{alloc,free}_contiguous() as a wrapper around
> the existing APIs so that users can be thoroughly checked and converted
> one-by-one.
Yeah. Actually given all the contention I wonder if the easiest solution
for now is to just open code the cma_alloc/cma_free calls in dma-direct
and dma-iommu, with the hopes that everyone is going to migrate to those
implementations in the mid-term anyway and dma_alloc_from_contiguous /
dma_release_from_contiguous just go away..
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu
WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: Robin Murphy <robin.murphy@arm.com>
Cc: tony@atomide.com, catalin.marinas@arm.com, will.deacon@arm.com,
jcmvbkbc@gmail.com, Christoph Hellwig <hch@lst.de>,
m.szyprowski@samsung.com, sfr@canb.auug.org.au, joro@8bytes.org,
linux@armlinux.org.uk, treding@nvidia.com,
linux-xtensa@linux-xtensa.org, keescook@chromium.org,
Nicolin Chen <nicoleotsuka@gmail.com>,
akpm@linux-foundation.org, linux-arm-kernel@lists.infradead.org,
chris@zankel.net, wsa+renesas@sang-engineering.com,
linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
iamjoonsoo.kim@lge.com, dwmw2@infradead.org
Subject: Re: [RFC/RFT PATCH 1/2] dma-contiguous: Simplify dma_*_from_contiguous() function calls
Date: Tue, 30 Apr 2019 17:18:33 +0200 [thread overview]
Message-ID: <20190430151833.GB25447@lst.de> (raw)
In-Reply-To: <0e3e6d8b-de44-d23e-a039-8d11b578ec5c@arm.com>
On Tue, Apr 30, 2019 at 01:37:54PM +0100, Robin Murphy wrote:
> On 30/04/2019 11:56, Christoph Hellwig wrote:
>> So while I really, really like this cleanup it turns out it isn't
>> actually safe for arm :( arm remaps the CMA allocation in place
>> instead of using a new mapping, which can be done because they don't
>> share PMDs with the kernel.
>>
>> So we'll probably need a __dma_alloc_from_contiguous version with
>> an additional bool fallback argument - everyone but arms uses
>> dma_alloc_from_contiguous as in your patch, just arm will get the
>> non-fallback one.
>
> Or we even just implement dma_{alloc,free}_contiguous() as a wrapper around
> the existing APIs so that users can be thoroughly checked and converted
> one-by-one.
Yeah. Actually given all the contention I wonder if the easiest solution
for now is to just open code the cma_alloc/cma_free calls in dma-direct
and dma-iommu, with the hopes that everyone is going to migrate to those
implementations in the mid-term anyway and dma_alloc_from_contiguous /
dma_release_from_contiguous just go away..
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2019-04-30 15:18 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-30 1:55 [RFC/RFT PATCH 0/2] Optimize dma_*_from_contiguous calls Nicolin Chen
2019-04-30 1:55 ` Nicolin Chen
2019-04-30 1:55 ` Nicolin Chen
2019-04-30 1:55 ` Nicolin Chen
2019-04-30 1:55 ` [RFC/RFT PATCH 1/2] dma-contiguous: Simplify dma_*_from_contiguous() function calls Nicolin Chen
2019-04-30 1:55 ` Nicolin Chen
2019-04-30 1:55 ` Nicolin Chen
2019-04-30 1:55 ` Nicolin Chen
2019-04-30 10:56 ` Christoph Hellwig
2019-04-30 10:56 ` Christoph Hellwig
2019-04-30 10:56 ` Christoph Hellwig
2019-04-30 12:37 ` Robin Murphy
2019-04-30 12:37 ` Robin Murphy
2019-04-30 12:37 ` Robin Murphy
2019-04-30 15:18 ` Christoph Hellwig [this message]
2019-04-30 15:18 ` Christoph Hellwig
2019-04-30 15:18 ` Christoph Hellwig
2019-04-30 19:46 ` Nicolin Chen
2019-04-30 19:46 ` Nicolin Chen
2019-04-30 19:46 ` Nicolin Chen
2019-04-30 12:52 ` Robin Murphy
2019-04-30 12:52 ` Robin Murphy
2019-04-30 12:52 ` Robin Murphy
2019-04-30 15:20 ` Christoph Hellwig
2019-04-30 15:20 ` Christoph Hellwig
2019-04-30 15:20 ` Christoph Hellwig
2019-04-30 1:55 ` [RFC/RFT PATCH 2/2] dma-contiguous: Use fallback alloc_pages for single pages Nicolin Chen
2019-04-30 1:55 ` Nicolin Chen
2019-04-30 1:55 ` Nicolin Chen
2019-04-30 1:55 ` Nicolin Chen
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