From: Robin Murphy <robin.murphy-5wv7dgnIgG8@public.gmane.org>
To: Yong Wu <yong.wu-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org>
Cc: "laurent.pinchart+renesas-ryLnwIuWjnjg/C1BVhZhaw@public.gmane.org"
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<linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org>
Subject: Re: [PATCH v2 2/4] iommu: Implement common IOMMU ops for DMA mapping
Date: Thu, 18 Jun 2015 17:54:29 +0100 [thread overview]
Message-ID: <5582F7C5.8060901@arm.com> (raw)
In-Reply-To: <1434639625.26953.12.camel@mhfsdcap03>
On 18/06/15 16:00, Yong Wu wrote:
> Hi Robin,
> while our drm test, we meet a problem while dma-mmap.
>
> On Thu, 2015-06-11 at 16:54 +0100, Robin Murphy wrote:
>> Taking inspiration from the existing arch/arm code, break out some
>> generic functions to interface the DMA-API to the IOMMU-API. This will
>> do the bulk of the heavy lifting for IOMMU-backed dma-mapping.
>>
>> Signed-off-by: Robin Murphy <robin.murphy-5wv7dgnIgG8@public.gmane.org>
>> ---
>> drivers/iommu/Kconfig | 7 +
>> drivers/iommu/Makefile | 1 +
>> drivers/iommu/dma-iommu.c | 560 ++++++++++++++++++++++++++++++++++++++++++++++
>> include/linux/dma-iommu.h | 94 ++++++++
>> 4 files changed, 662 insertions(+)
>> create mode 100644 drivers/iommu/dma-iommu.c
>> create mode 100644 include/linux/dma-iommu.h
>>
> [snip]
>> +/**
>> + * iommu_dma_mmap - Map a buffer into provided user VMA
>> + * @pages: Array representing buffer from iommu_dma_alloc()
>> + * @size: Size of buffer in bytes
>> + * @vma: VMA describing requested userspace mapping
>> + *
>> + * Maps the pages of the buffer in @pages into @vma. The caller is responsible
>> + * for verifying the correct size and protection of @vma beforehand.
>> + */
>> +
>> +int iommu_dma_mmap(struct page **pages, size_t size, struct vm_area_struct *vma)
>> +{
>> + unsigned long uaddr = vma->vm_start;
>> + unsigned int i, count = PAGE_ALIGN(size) >> PAGE_SHIFT;
>> + int ret = -ENXIO;
>> +
>> + for (i = vma->vm_pgoff; i < count && uaddr < vma->vm_end; i++) {
> Is it : for (i = 0; i < count && uaddr < vma->vm_end; i++)
According to the patches at [1], respecting vma->pgoff is necessary for
users who only want to mmap part of the buffer. Does your DRM driver by
any chance need the same fix as the Rockchip one?
>> + ret = vm_insert_page(vma, uaddr, pages[i]);
>> + if (ret)
>> + break;
>> + uaddr += PAGE_SIZE;
>> + }
>> + return ret;
>> +}
>> +
And to save another email:
>> + if (WARN_ON(!area || area->pages))
> Is it: if (WARN_ON(!area || !area->pages))
>> + return -ENXIO;
You're absolutely right, thanks. I've got a couple more bugfixes in
progress too, so I'll try to get an updated branch pushed out soon; I'll
hold off posting a v3 to the list until after the upcoming merge window,
though.
Robin.
[1]:http://thread.gmane.org/gmane.linux.kernel/1932343
WARNING: multiple messages have this Message-ID (diff)
From: robin.murphy@arm.com (Robin Murphy)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 2/4] iommu: Implement common IOMMU ops for DMA mapping
Date: Thu, 18 Jun 2015 17:54:29 +0100 [thread overview]
Message-ID: <5582F7C5.8060901@arm.com> (raw)
In-Reply-To: <1434639625.26953.12.camel@mhfsdcap03>
On 18/06/15 16:00, Yong Wu wrote:
> Hi Robin,
> while our drm test, we meet a problem while dma-mmap.
>
> On Thu, 2015-06-11 at 16:54 +0100, Robin Murphy wrote:
>> Taking inspiration from the existing arch/arm code, break out some
>> generic functions to interface the DMA-API to the IOMMU-API. This will
>> do the bulk of the heavy lifting for IOMMU-backed dma-mapping.
>>
>> Signed-off-by: Robin Murphy <robin.murphy@arm.com>
>> ---
>> drivers/iommu/Kconfig | 7 +
>> drivers/iommu/Makefile | 1 +
>> drivers/iommu/dma-iommu.c | 560 ++++++++++++++++++++++++++++++++++++++++++++++
>> include/linux/dma-iommu.h | 94 ++++++++
>> 4 files changed, 662 insertions(+)
>> create mode 100644 drivers/iommu/dma-iommu.c
>> create mode 100644 include/linux/dma-iommu.h
>>
> [snip]
>> +/**
>> + * iommu_dma_mmap - Map a buffer into provided user VMA
>> + * @pages: Array representing buffer from iommu_dma_alloc()
>> + * @size: Size of buffer in bytes
>> + * @vma: VMA describing requested userspace mapping
>> + *
>> + * Maps the pages of the buffer in @pages into @vma. The caller is responsible
>> + * for verifying the correct size and protection of @vma beforehand.
>> + */
>> +
>> +int iommu_dma_mmap(struct page **pages, size_t size, struct vm_area_struct *vma)
>> +{
>> + unsigned long uaddr = vma->vm_start;
>> + unsigned int i, count = PAGE_ALIGN(size) >> PAGE_SHIFT;
>> + int ret = -ENXIO;
>> +
>> + for (i = vma->vm_pgoff; i < count && uaddr < vma->vm_end; i++) {
> Is it : for (i = 0; i < count && uaddr < vma->vm_end; i++)
According to the patches at [1], respecting vma->pgoff is necessary for
users who only want to mmap part of the buffer. Does your DRM driver by
any chance need the same fix as the Rockchip one?
>> + ret = vm_insert_page(vma, uaddr, pages[i]);
>> + if (ret)
>> + break;
>> + uaddr += PAGE_SIZE;
>> + }
>> + return ret;
>> +}
>> +
And to save another email:
>> + if (WARN_ON(!area || area->pages))
> Is it: if (WARN_ON(!area || !area->pages))
>> + return -ENXIO;
You're absolutely right, thanks. I've got a couple more bugfixes in
progress too, so I'll try to get an updated branch pushed out soon; I'll
hold off posting a v3 to the list until after the upcoming merge window,
though.
Robin.
[1]:http://thread.gmane.org/gmane.linux.kernel/1932343
next prev parent reply other threads:[~2015-06-18 16:54 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-11 15:54 [PATCH v2 0/4] arm64: IOMMU-backed DMA mapping Robin Murphy
2015-06-11 15:54 ` Robin Murphy
[not found] ` <cover.1434036796.git.robin.murphy-5wv7dgnIgG8@public.gmane.org>
2015-06-11 15:54 ` [PATCH v2 1/4] iommu/iova: Avoid over-allocating when size-aligned Robin Murphy
2015-06-11 15:54 ` Robin Murphy
2015-06-11 15:54 ` [PATCH v2 2/4] iommu: Implement common IOMMU ops for DMA mapping Robin Murphy
2015-06-11 15:54 ` Robin Murphy
[not found] ` <bf63d80c36533aa4dcc401b5a4b312ba00237e1c.1434036796.git.robin.murphy-5wv7dgnIgG8@public.gmane.org>
2015-06-18 15:00 ` Yong Wu
2015-06-18 15:00 ` Yong Wu
2015-06-18 16:54 ` Robin Murphy [this message]
2015-06-18 16:54 ` Robin Murphy
[not found] ` <5582F7C5.8060901-5wv7dgnIgG8@public.gmane.org>
2015-06-19 1:06 ` Yong Wu
2015-06-19 1:06 ` Yong Wu
2015-07-03 9:27 ` Yong Wu
2015-07-03 9:27 ` Yong Wu
2015-07-03 16:44 ` Robin Murphy
2015-07-03 16:44 ` Robin Murphy
[not found] ` <5596BBD3.1040708-5wv7dgnIgG8@public.gmane.org>
2015-07-07 7:37 ` Yong Wu
2015-07-07 7:37 ` Yong Wu
2015-06-11 15:54 ` [PATCH v2 3/4] arm64: Add IOMMU dma_ops Robin Murphy
2015-06-11 15:54 ` Robin Murphy
[not found] ` <4e298538ccedbe6f593d8edc40eb3a08ad9e4df5.1434036796.git.robin.murphy-5wv7dgnIgG8@public.gmane.org>
2015-06-18 15:00 ` Yong Wu
2015-06-18 15:00 ` Yong Wu
2015-06-11 15:54 ` [PATCH v2 4/4] arm64: Hook up " Robin Murphy
2015-06-11 15:54 ` Robin Murphy
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