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From: Christoph Hellwig <hch@lst.de>
To: Nicolin Chen <nicoleotsuka@gmail.com>
Cc: hch@lst.de, robin.murphy@arm.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 12:56:40 +0200	[thread overview]
Message-ID: <20190430105640.GA20021@lst.de> (raw)
In-Reply-To: <20190430015521.27734-2-nicoleotsuka@gmail.com>

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.

Sorry for not sorting this our earlier.

WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: Nicolin Chen <nicoleotsuka@gmail.com>
Cc: tony@atomide.com, catalin.marinas@arm.com, will.deacon@arm.com,
	jcmvbkbc@gmail.com, hch@lst.de, sfr@canb.auug.org.au,
	linux@armlinux.org.uk, treding@nvidia.com,
	linux-xtensa@linux-xtensa.org, keescook@chromium.org,
	akpm@linux-foundation.org, linux-arm-kernel@lists.infradead.org,
	chris@zankel.net, wsa+renesas@sang-engineering.com,
	robin.murphy@arm.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 12:56:40 +0200	[thread overview]
Message-ID: <20190430105640.GA20021@lst.de> (raw)
Message-ID: <20190430105640.2yqTdQD01DQTNiTwHAR9POsmLbDqzLWV_T0Tio1-wRo@z> (raw)
In-Reply-To: <20190430015521.27734-2-nicoleotsuka@gmail.com>

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.

Sorry for not sorting this our earlier.
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu

  parent reply	other threads:[~2019-04-30 10:56 UTC|newest]

Thread overview: 18+ 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 ` [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 10:56   ` Christoph Hellwig [this message]
2019-04-30 10:56     ` Christoph Hellwig
2019-04-30 12:37     ` Robin Murphy
2019-04-30 12:37       ` Robin Murphy
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 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  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

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