All of lore.kernel.org
 help / color / mirror / Atom feed
From: Christoph Hellwig <hch@lst.de>
To: Gavin Li <gavinli@thegavinli.com>
Cc: Christoph Hellwig <hch@lst.de>,
	Shawn Anastasio <shawn@anastas.io>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Russell King <linux@armlinux.org.uk>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	Robin Murphy <robin.murphy@arm.com>,
	Paul Burton <paul.burton@mips.com>,
	James Hogan <jhogan@kernel.org>,
	linuxppc-dev@lists.ozlabs.org, linux-mips@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, Gavin Li <git@thegavinli.com>
Subject: Re: [PATCH 1/2] dma-mapping: fix page attributes for dma_mmap_*
Date: Tue, 6 Aug 2019 07:12:42 +0200	[thread overview]
Message-ID: <20190806051242.GA13269@lst.de> (raw)
In-Reply-To: <CA+GxvY5C_rrukCzC5K-h72bePyW8PS_Rfj3uxh-K6UrcAextUQ@mail.gmail.com>

On Mon, Aug 05, 2019 at 07:55:44PM -0700, Gavin Li wrote:
> >         /* create a coherent mapping */
> >         ret = dma_common_contiguous_remap(page, size, VM_USERMAP,
> > -                       arch_dma_mmap_pgprot(dev, PAGE_KERNEL, attrs),
> > +                       dma_pgprot(dev, PAGE_KERNEL, attrs),
> >                         __builtin_return_address(0));
> >         if (!ret) {
> >                 __dma_direct_free_pages(dev, size, page);
> 
> Is dma_common_contiguous_remap() still necessary in the
> DMA_ATTR_NON_CONSISTENT case? I would presume it would be fine to just
> return a linearly mapped address in that case.

It would not be required for a real DMA_ATTR_NON_CONSISTENT
implementation.  But only parisc and mips actually properly implement
DMA_ATTR_NON_CONSISTENT, everyone ignores it.  Given that the API is
a little ill defined and I have a better replacement in the pipeline
I don't want to start implementing it for other architectures now.

WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: Gavin Li <gavinli@thegavinli.com>
Cc: Gavin Li <git@thegavinli.com>, Shawn Anastasio <shawn@anastas.io>,
	linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
	Russell King <linux@armlinux.org.uk>,
	linux-mips@vger.kernel.org, Paul Burton <paul.burton@mips.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	James Hogan <jhogan@kernel.org>, Will Deacon <will@kernel.org>,
	Christoph Hellwig <hch@lst.de>,
	linux-arm-kernel@lists.infradead.org,
	Robin Murphy <robin.murphy@arm.com>
Subject: Re: [PATCH 1/2] dma-mapping: fix page attributes for dma_mmap_*
Date: Tue, 6 Aug 2019 07:12:42 +0200	[thread overview]
Message-ID: <20190806051242.GA13269@lst.de> (raw)
In-Reply-To: <CA+GxvY5C_rrukCzC5K-h72bePyW8PS_Rfj3uxh-K6UrcAextUQ@mail.gmail.com>

On Mon, Aug 05, 2019 at 07:55:44PM -0700, Gavin Li wrote:
> >         /* create a coherent mapping */
> >         ret = dma_common_contiguous_remap(page, size, VM_USERMAP,
> > -                       arch_dma_mmap_pgprot(dev, PAGE_KERNEL, attrs),
> > +                       dma_pgprot(dev, PAGE_KERNEL, attrs),
> >                         __builtin_return_address(0));
> >         if (!ret) {
> >                 __dma_direct_free_pages(dev, size, page);
> 
> Is dma_common_contiguous_remap() still necessary in the
> DMA_ATTR_NON_CONSISTENT case? I would presume it would be fine to just
> return a linearly mapped address in that case.

It would not be required for a real DMA_ATTR_NON_CONSISTENT
implementation.  But only parisc and mips actually properly implement
DMA_ATTR_NON_CONSISTENT, everyone ignores it.  Given that the API is
a little ill defined and I have a better replacement in the pipeline
I don't want to start implementing it for other architectures now.

WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: Gavin Li <gavinli@thegavinli.com>
Cc: Gavin Li <git@thegavinli.com>, Shawn Anastasio <shawn@anastas.io>,
	Michael Ellerman <mpe@ellerman.id.au>,
	linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
	Russell King <linux@armlinux.org.uk>,
	linux-mips@vger.kernel.org, Paul Burton <paul.burton@mips.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	James Hogan <jhogan@kernel.org>, Will Deacon <will@kernel.org>,
	Christoph Hellwig <hch@lst.de>,
	linux-arm-kernel@lists.infradead.org,
	Robin Murphy <robin.murphy@arm.com>
Subject: Re: [PATCH 1/2] dma-mapping: fix page attributes for dma_mmap_*
Date: Tue, 6 Aug 2019 07:12:42 +0200	[thread overview]
Message-ID: <20190806051242.GA13269@lst.de> (raw)
In-Reply-To: <CA+GxvY5C_rrukCzC5K-h72bePyW8PS_Rfj3uxh-K6UrcAextUQ@mail.gmail.com>

On Mon, Aug 05, 2019 at 07:55:44PM -0700, Gavin Li wrote:
> >         /* create a coherent mapping */
> >         ret = dma_common_contiguous_remap(page, size, VM_USERMAP,
> > -                       arch_dma_mmap_pgprot(dev, PAGE_KERNEL, attrs),
> > +                       dma_pgprot(dev, PAGE_KERNEL, attrs),
> >                         __builtin_return_address(0));
> >         if (!ret) {
> >                 __dma_direct_free_pages(dev, size, page);
> 
> Is dma_common_contiguous_remap() still necessary in the
> DMA_ATTR_NON_CONSISTENT case? I would presume it would be fine to just
> return a linearly mapped address in that case.

It would not be required for a real DMA_ATTR_NON_CONSISTENT
implementation.  But only parisc and mips actually properly implement
DMA_ATTR_NON_CONSISTENT, everyone ignores it.  Given that the API is
a little ill defined and I have a better replacement in the pipeline
I don't want to start implementing it for other architectures now.

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply	other threads:[~2019-08-06  5:12 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-05  8:01 fix default dma_mmap_* pgprot v2 Christoph Hellwig
2019-08-05  8:01 ` Christoph Hellwig
2019-08-05  8:01 ` Christoph Hellwig
2019-08-05  8:01 ` Christoph Hellwig
2019-08-05  8:01 ` [PATCH 1/2] dma-mapping: fix page attributes for dma_mmap_* Christoph Hellwig
2019-08-05  8:01   ` Christoph Hellwig
2019-08-05  8:01   ` Christoph Hellwig
2019-08-05  8:01   ` Christoph Hellwig
2019-08-05  9:10   ` Catalin Marinas
2019-08-05  9:10     ` Catalin Marinas
2019-08-05  9:10     ` Catalin Marinas
2019-08-05  9:10     ` Catalin Marinas
     [not found]   ` <CAP_+7SzPdNCMKuuXMjHjpCzxsey2YWR_e6mTAWtNSZ6kKBvKFw@mail.gmail.com>
2019-08-06  2:55     ` Gavin Li
2019-08-06  2:55       ` Gavin Li
2019-08-06  2:55       ` Gavin Li
2019-08-06  5:12       ` Christoph Hellwig [this message]
2019-08-06  5:12         ` Christoph Hellwig
2019-08-06  5:12         ` Christoph Hellwig
2019-08-06 19:39   ` Shawn Anastasio via iommu
2019-08-06 19:39     ` Shawn Anastasio
2019-08-06 19:39     ` Shawn Anastasio
2019-08-06 19:39     ` Shawn Anastasio
2019-08-07  6:04     ` Christoph Hellwig
2019-08-07  6:04       ` Christoph Hellwig
2019-08-07  6:04       ` Christoph Hellwig
2019-08-07  6:04       ` Christoph Hellwig
2019-08-07 11:45       ` Shawn Anastasio via iommu
2019-08-07 11:45         ` Shawn Anastasio
2019-08-07 11:45         ` Shawn Anastasio
2019-08-07 11:45         ` Shawn Anastasio
2019-08-05  8:01 ` [PATCH 2/2] MIPS: remove support for DMA_ATTR_WRITE_COMBINE Christoph Hellwig
2019-08-05  8:01   ` Christoph Hellwig
2019-08-05  8:01   ` Christoph Hellwig
2019-08-05  8:01   ` Christoph Hellwig
2019-08-05  8:06   ` Sergei Shtylyov
2019-08-05  8:06     ` Sergei Shtylyov
2019-08-05  8:06     ` Sergei Shtylyov
2019-08-05  8:06     ` Sergei Shtylyov
  -- strict thread matches above, loose matches on Subject: below --
2019-08-07  6:16 fix default dma_mmap_* pgprot v3 Christoph Hellwig
2019-08-07  6:16 ` [PATCH 1/2] dma-mapping: fix page attributes for dma_mmap_* Christoph Hellwig
2019-08-07  6:16   ` Christoph Hellwig
2019-08-07  6:16   ` Christoph Hellwig
2019-08-07  6:16   ` Christoph Hellwig

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20190806051242.GA13269@lst.de \
    --to=hch@lst.de \
    --cc=catalin.marinas@arm.com \
    --cc=gavinli@thegavinli.com \
    --cc=git@thegavinli.com \
    --cc=jhogan@kernel.org \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mips@vger.kernel.org \
    --cc=linux@armlinux.org.uk \
    --cc=linuxppc-dev@lists.ozlabs.org \
    --cc=mpe@ellerman.id.au \
    --cc=paul.burton@mips.com \
    --cc=robin.murphy@arm.com \
    --cc=shawn@anastas.io \
    --cc=will@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.