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From: Christoph Hellwig <hch@lst.de>
To: Paul Burton <paul.burton@mips.com>
Cc: Christoph Hellwig <hch@lst.de>,
	Ralf Baechle <ralf@linux-mips.org>,
	James Hogan <jhogan@kernel.org>, Ley Foon Tan <lftan@altera.com>,
	Michal Simek <monstr@monstr.eu>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
	"linux-mips@vger.kernel.org" <linux-mips@vger.kernel.org>,
	"iommu@lists.linux-foundation.org"
	<iommu@lists.linux-foundation.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-fbdev@vger.kernel.org" <linux-fbdev@vger.kernel.org>
Subject: Re: [PATCH 5/7] MIPS: use the generic uncached segment support in dma-direct
Date: Tue, 30 Apr 2019 21:15:54 +0000	[thread overview]
Message-ID: <20190430211553.GA31109@lst.de> (raw)
In-Reply-To: <20190430211105.ielntedm46uqamca@pburton-laptop>

On Tue, Apr 30, 2019 at 09:11:07PM +0000, Paul Burton wrote:
> Right but dma_direct_alloc_pages() already checks for the PageHighMem
> case & returns before ever calling arch_dma_prep_coherent(), no?

True.  And of course it can't be remapped into the uncached segment
anyway.  So yes, we should drop it.  Eventually I want to add generic
support for DMA_ATTR_NO_KERNEL_MAPPING, but that'll involved auditing
all instances anyway.

WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: Paul Burton <paul.burton@mips.com>
Cc: Christoph Hellwig <hch@lst.de>,
	Ralf Baechle <ralf@linux-mips.org>,
	James Hogan <jhogan@kernel.org>, Ley Foon Tan <lftan@altera.com>,
	Michal Simek <monstr@monstr.eu>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
	"linux-mips@vger.kernel.org" <linux-mips@vger.kernel.org>,
	"iommu@lists.linux-foundation.org"
	<iommu@lists.linux-foundation.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-fbdev@vger.kernel.org" <linux-fbdev@vger.kernel.org>
Subject: Re: [PATCH 5/7] MIPS: use the generic uncached segment support in dma-direct
Date: Tue, 30 Apr 2019 23:15:54 +0200	[thread overview]
Message-ID: <20190430211553.GA31109@lst.de> (raw)
In-Reply-To: <20190430211105.ielntedm46uqamca@pburton-laptop>

On Tue, Apr 30, 2019 at 09:11:07PM +0000, Paul Burton wrote:
> Right but dma_direct_alloc_pages() already checks for the PageHighMem
> case & returns before ever calling arch_dma_prep_coherent(), no?

True.  And of course it can't be remapped into the uncached segment
anyway.  So yes, we should drop it.  Eventually I want to add generic
support for DMA_ATTR_NO_KERNEL_MAPPING, but that'll involved auditing
all instances anyway.

WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: Paul Burton <paul.burton@mips.com>
Cc: Michal Simek <monstr@monstr.eu>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
	James Hogan <jhogan@kernel.org>,
	"linux-mips@vger.kernel.org" <linux-mips@vger.kernel.org>,
	Ralf Baechle <ralf@linux-mips.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"iommu@lists.linux-foundation.org"
	<iommu@lists.linux-foundation.org>,
	"linux-fbdev@vger.kernel.org" <linux-fbdev@vger.kernel.org>,
	Ley Foon Tan <lftan@altera.com>, Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH 5/7] MIPS: use the generic uncached segment support in dma-direct
Date: Tue, 30 Apr 2019 23:15:54 +0200	[thread overview]
Message-ID: <20190430211553.GA31109@lst.de> (raw)
Message-ID: <20190430211554.YqNcb_VlvOcdOqc_6LZ9-2A-OsMtDlJstInjPxV6jZY@z> (raw)
In-Reply-To: <20190430211105.ielntedm46uqamca@pburton-laptop>

On Tue, Apr 30, 2019 at 09:11:07PM +0000, Paul Burton wrote:
> Right but dma_direct_alloc_pages() already checks for the PageHighMem
> case & returns before ever calling arch_dma_prep_coherent(), no?

True.  And of course it can't be remapped into the uncached segment
anyway.  So yes, we should drop it.  Eventually I want to add generic
support for DMA_ATTR_NO_KERNEL_MAPPING, but that'll involved auditing
all instances anyway.
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iommu@lists.linux-foundation.org
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  reply	other threads:[~2019-04-30 21:15 UTC|newest]

Thread overview: 79+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-30 11:00 provide generic support for uncached segements in dma-direct Christoph Hellwig
2019-04-30 11:00 ` Christoph Hellwig
2019-04-30 11:00 ` Christoph Hellwig
2019-04-30 11:00 ` [PATCH 1/7] MIPS: remove the _dma_cache_wback_inv export Christoph Hellwig
2019-04-30 11:00   ` Christoph Hellwig
2019-04-30 11:00   ` Christoph Hellwig
2019-04-30 11:00 ` [PATCH 2/7] au1100fb: fix DMA API abuse Christoph Hellwig
2019-04-30 11:00   ` Christoph Hellwig
2019-04-30 11:00   ` Christoph Hellwig
2019-05-06 13:49   ` Bartlomiej Zolnierkiewicz
2019-05-06 13:49     ` Bartlomiej Zolnierkiewicz
2019-05-06 13:49     ` Bartlomiej Zolnierkiewicz
2019-05-07  6:36     ` Christoph Hellwig
2019-05-07  6:36       ` Christoph Hellwig
2019-05-07  6:36       ` Christoph Hellwig
2019-05-07  7:02       ` Manuel Lauss
2019-06-03  6:49     ` Christoph Hellwig
2019-06-03  6:49       ` Christoph Hellwig
2019-06-03  6:49       ` Christoph Hellwig
2019-04-30 11:00 ` [PATCH 3/7] dma-mapping: add a Kconfig symbol to indicate arch_dma_prep_coherent presence Christoph Hellwig
2019-04-30 11:00   ` Christoph Hellwig
2019-04-30 11:00   ` Christoph Hellwig
2019-04-30 11:00 ` [PATCH 4/7] dma-direct: provide generic support for uncached kernel segments Christoph Hellwig
2019-04-30 11:00   ` Christoph Hellwig
2019-04-30 11:00   ` Christoph Hellwig
2019-05-01 17:18   ` Paul Burton
2019-05-01 17:18     ` Paul Burton
2019-05-01 17:18     ` Paul Burton
2019-05-01 17:29     ` Christoph Hellwig
2019-05-01 17:29       ` Christoph Hellwig
2019-05-01 17:29       ` Christoph Hellwig
2019-05-01 17:29       ` Christoph Hellwig
2019-05-01 17:40       ` Paul Burton
2019-05-01 17:40         ` Paul Burton
2019-05-01 17:40         ` Paul Burton
2019-05-01 17:49         ` Christoph Hellwig
2019-05-01 17:49           ` Christoph Hellwig
2019-05-01 17:49           ` Christoph Hellwig
2019-05-02  0:08           ` Paul Burton
2019-05-02  0:08             ` Paul Burton
2019-05-02  0:08             ` Paul Burton
2019-05-02 13:11             ` Christoph Hellwig
2019-05-02 13:11               ` Christoph Hellwig
2019-05-02 13:11               ` Christoph Hellwig
2019-05-02 13:11               ` Christoph Hellwig
2019-04-30 11:00 ` [PATCH 5/7] MIPS: use the generic uncached segment support in dma-direct Christoph Hellwig
2019-04-30 11:00   ` Christoph Hellwig
2019-04-30 11:00   ` Christoph Hellwig
2019-04-30 20:10   ` Paul Burton
2019-04-30 20:10     ` Paul Burton
2019-04-30 20:29     ` Christoph Hellwig
2019-04-30 20:29       ` Christoph Hellwig
2019-04-30 20:29       ` Christoph Hellwig
2019-04-30 21:11       ` Paul Burton
2019-04-30 21:11         ` Paul Burton
2019-04-30 21:15         ` Christoph Hellwig [this message]
2019-04-30 21:15           ` Christoph Hellwig
2019-04-30 21:15           ` Christoph Hellwig
2019-05-01 13:13         ` [PATCH 5/7 v2] " Christoph Hellwig
2019-05-01 13:13           ` Christoph Hellwig
2019-05-01 13:13           ` Christoph Hellwig
2019-05-01 17:13           ` Paul Burton
2019-05-01 17:13             ` Paul Burton
2019-05-01 17:13             ` Paul Burton
2019-06-03  6:48             ` Christoph Hellwig
2019-06-03  6:48               ` Christoph Hellwig
2019-06-03  6:48               ` Christoph Hellwig
2019-07-03  8:54               ` Arnd Bergmann
2019-07-03  8:54                 ` Arnd Bergmann
2019-07-03  8:54                 ` Arnd Bergmann
2019-07-03 12:13                 ` Christoph Hellwig
2019-07-03 12:13                   ` Christoph Hellwig
2019-07-03 12:13                   ` Christoph Hellwig
2019-04-30 11:00 ` [PATCH 6/7] nios2: " Christoph Hellwig
2019-04-30 11:00   ` Christoph Hellwig
2019-04-30 11:00   ` Christoph Hellwig
2019-04-30 11:00 ` [PATCH 7/7] microblaze: " Christoph Hellwig
2019-04-30 11:00   ` Christoph Hellwig
2019-04-30 11:00   ` Christoph Hellwig

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