Linux-ARM-Kernel Archive on lore.kernel.org
 help / color / Atom feed
From: Marek Szyprowski <m.szyprowski@samsung.com>
To: "Christoph Hellwig" <hch@lst.de>,
	"Pawel Osciak" <pawel@osciak.com>,
	"Kyungmin Park" <kyungmin.park@samsung.com>,
	"Niklas Söderlund" <niklas.soderlund+renesas@ragnatech.se>
Cc: Russell King <linux@armlinux.org.uk>,
	linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
	Mauro Carvalho Chehab <mchehab@kernel.org>,
	linuxppc-dev@lists.ozlabs.org,
	linux-arm-kernel@lists.infradead.org,
	linux-media@vger.kernel.org
Subject: Re: [PATCH 3/3] videobuf2: replace a layering violation with dma_map_resource
Date: Mon, 14 Jan 2019 13:42:26 +0100
Message-ID: <6f8892ac-c2aa-10df-c74f-ba032bf75160@samsung.com> (raw)
In-Reply-To: <20190111181731.11782-4-hch@lst.de>

Hi Christoph,

On 2019-01-11 19:17, Christoph Hellwig wrote:
> vb2_dc_get_userptr pokes into arm direct mapping details to get the
> resemblance of a dma address for a a physical address that does is
> not backed by a page struct.  Not only is this not portable to other
> architectures with dma direct mapping offsets, but also not to uses
> of IOMMUs of any kind.  Switch to the proper dma_map_resource /
> dma_unmap_resource interface instead.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>

There are checks for IOMMU presence in other places in vb2-dma-contig,
so it was used only when no IOMMU is available, but I agree that the
hacky code should be replaced by a generic code if possible.

Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>

V4L2 pipeline works fine on older Exynos-based boards with CMA and IOMMU
disabled.

> ---
>  .../common/videobuf2/videobuf2-dma-contig.c   | 41 ++++---------------
>  1 file changed, 9 insertions(+), 32 deletions(-)
>
> diff --git a/drivers/media/common/videobuf2/videobuf2-dma-contig.c b/drivers/media/common/videobuf2/videobuf2-dma-contig.c
> index aff0ab7bf83d..82389aead6ed 100644
> --- a/drivers/media/common/videobuf2/videobuf2-dma-contig.c
> +++ b/drivers/media/common/videobuf2/videobuf2-dma-contig.c
> @@ -439,42 +439,14 @@ static void vb2_dc_put_userptr(void *buf_priv)
>  				set_page_dirty_lock(pages[i]);
>  		sg_free_table(sgt);
>  		kfree(sgt);
> +	} else {
> +		dma_unmap_resource(buf->dev, buf->dma_addr, buf->size,
> +				   buf->dma_dir, 0);
>  	}
>  	vb2_destroy_framevec(buf->vec);
>  	kfree(buf);
>  }
>  
> -/*
> - * For some kind of reserved memory there might be no struct page available,
> - * so all that can be done to support such 'pages' is to try to convert
> - * pfn to dma address or at the last resort just assume that
> - * dma address == physical address (like it has been assumed in earlier version
> - * of videobuf2-dma-contig
> - */
> -
> -#ifdef __arch_pfn_to_dma
> -static inline dma_addr_t vb2_dc_pfn_to_dma(struct device *dev, unsigned long pfn)
> -{
> -	return (dma_addr_t)__arch_pfn_to_dma(dev, pfn);
> -}
> -#elif defined(__pfn_to_bus)
> -static inline dma_addr_t vb2_dc_pfn_to_dma(struct device *dev, unsigned long pfn)
> -{
> -	return (dma_addr_t)__pfn_to_bus(pfn);
> -}
> -#elif defined(__pfn_to_phys)
> -static inline dma_addr_t vb2_dc_pfn_to_dma(struct device *dev, unsigned long pfn)
> -{
> -	return (dma_addr_t)__pfn_to_phys(pfn);
> -}
> -#else
> -static inline dma_addr_t vb2_dc_pfn_to_dma(struct device *dev, unsigned long pfn)
> -{
> -	/* really, we cannot do anything better at this point */
> -	return (dma_addr_t)(pfn) << PAGE_SHIFT;
> -}
> -#endif
> -
>  static void *vb2_dc_get_userptr(struct device *dev, unsigned long vaddr,
>  	unsigned long size, enum dma_data_direction dma_dir)
>  {
> @@ -528,7 +500,12 @@ static void *vb2_dc_get_userptr(struct device *dev, unsigned long vaddr,
>  		for (i = 1; i < n_pages; i++)
>  			if (nums[i-1] + 1 != nums[i])
>  				goto fail_pfnvec;
> -		buf->dma_addr = vb2_dc_pfn_to_dma(buf->dev, nums[0]);
> +		buf->dma_addr = dma_map_resource(buf->dev,
> +				__pfn_to_phys(nums[0]), size, buf->dma_dir, 0);
> +		if (dma_mapping_error(buf->dev, buf->dma_addr)) {
> +			ret = -ENOMEM;
> +			goto fail_pfnvec;
> +		}
>  		goto out;
>  	}
>  

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland


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

  parent reply index

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CGME20190111181841epcas3p2d7c0bf8f5c11a9863e22ec1b12da6e1b@epcas3p2.samsung.com>
2019-01-11 18:17 ` fix a layering violation in videobuf2 and improve dma_map_resource Christoph Hellwig
2019-01-11 18:17   ` [PATCH 1/3] dma-mapping: remove the default map_resource implementation Christoph Hellwig
2019-01-14 13:12     ` Robin Murphy
2019-01-14 17:08       ` Christoph Hellwig
2019-01-11 18:17   ` [PATCH 2/3] dma-mapping: don't BUG when calling dma_map_resource on RAM Christoph Hellwig
2019-01-14 14:16     ` Robin Murphy
2019-01-11 18:17   ` [PATCH 3/3] videobuf2: replace a layering violation with dma_map_resource Christoph Hellwig
2019-01-11 19:54     ` Mauro Carvalho Chehab
2019-01-14 10:31       ` Christoph Hellwig
2019-01-14 11:04         ` Mauro Carvalho Chehab
2019-01-14 11:12           ` Christoph Hellwig
2019-01-14 12:42     ` Marek Szyprowski [this message]
2019-01-17 17:21       ` Christoph Hellwig
2019-01-18  9:41         ` Marek Szyprowski
2019-01-31 15:31           ` Christoph Hellwig
2019-01-14 11:43   ` fix a layering violation in videobuf2 and improve dma_map_resource Marek Szyprowski
2019-01-18 11:37 fix a layering violation in videobuf2 and improve dma_map_resource v2 Christoph Hellwig
2019-01-18 11:37 ` [PATCH 3/3] videobuf2: replace a layering violation with dma_map_resource Christoph Hellwig

Reply instructions:

You may reply publically 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=6f8892ac-c2aa-10df-c74f-ba032bf75160@samsung.com \
    --to=m.szyprowski@samsung.com \
    --cc=hch@lst.de \
    --cc=iommu@lists.linux-foundation.org \
    --cc=kyungmin.park@samsung.com \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-media@vger.kernel.org \
    --cc=linux@armlinux.org.uk \
    --cc=linuxppc-dev@lists.ozlabs.org \
    --cc=mchehab@kernel.org \
    --cc=niklas.soderlund+renesas@ragnatech.se \
    --cc=pawel@osciak.com \
    /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

Linux-ARM-Kernel Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-arm-kernel/0 linux-arm-kernel/git/0.git
	git clone --mirror https://lore.kernel.org/linux-arm-kernel/1 linux-arm-kernel/git/1.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-arm-kernel linux-arm-kernel/ https://lore.kernel.org/linux-arm-kernel \
		linux-arm-kernel@lists.infradead.org infradead-linux-arm-kernel@archiver.kernel.org
	public-inbox-index linux-arm-kernel


Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.infradead.lists.linux-arm-kernel


AGPL code for this site: git clone https://public-inbox.org/ public-inbox