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 20:29:47 +0000 [thread overview]
Message-ID: <20190430202947.GA30262@lst.de> (raw)
In-Reply-To: <20190430201041.536amvinrcvd2wua@pburton-laptop>
On Tue, Apr 30, 2019 at 08:10:43PM +0000, Paul Burton wrote:
> This series looks like a nice cleanup to me - the one thing that puzzles
> me is the !PageHighMem check above.
>
> As far as I can see arch_dma_prep_coherent() should never be called with
> a highmem page, so would it make more sense to either drop this check or
> perhaps wrap it in a WARN_ON()?
dma_alloc_from_contigous can return highmem pages depending on where
the CMA area is located. But given that these pages don't have a
direct kernel mapping we also shouldn't have to flush the caches
for them.
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 22:29:47 +0200 [thread overview]
Message-ID: <20190430202947.GA30262@lst.de> (raw)
In-Reply-To: <20190430201041.536amvinrcvd2wua@pburton-laptop>
On Tue, Apr 30, 2019 at 08:10:43PM +0000, Paul Burton wrote:
> This series looks like a nice cleanup to me - the one thing that puzzles
> me is the !PageHighMem check above.
>
> As far as I can see arch_dma_prep_coherent() should never be called with
> a highmem page, so would it make more sense to either drop this check or
> perhaps wrap it in a WARN_ON()?
dma_alloc_from_contigous can return highmem pages depending on where
the CMA area is located. But given that these pages don't have a
direct kernel mapping we also shouldn't have to flush the caches
for them.
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 22:29:47 +0200 [thread overview]
Message-ID: <20190430202947.GA30262@lst.de> (raw)
Message-ID: <20190430202947.CelEiGVTXKYGuNjLtrjejQM1EhDPtnrY5_IIyPo7Qeg@z> (raw)
In-Reply-To: <20190430201041.536amvinrcvd2wua@pburton-laptop>
On Tue, Apr 30, 2019 at 08:10:43PM +0000, Paul Burton wrote:
> This series looks like a nice cleanup to me - the one thing that puzzles
> me is the !PageHighMem check above.
>
> As far as I can see arch_dma_prep_coherent() should never be called with
> a highmem page, so would it make more sense to either drop this check or
> perhaps wrap it in a WARN_ON()?
dma_alloc_from_contigous can return highmem pages depending on where
the CMA area is located. But given that these pages don't have a
direct kernel mapping we also shouldn't have to flush the caches
for them.
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iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu
next prev parent reply other threads:[~2019-04-30 20:29 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 [this message]
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
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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