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From: Sergey Senozhatsky <sergey.senozhatsky at gmail.com> The patch partially reverts some of the UAPI bits of the buffer cache management hints. Namely, the queue consistency (memory coherency) user-space hint because, as it turned out, the kernel implementation of this feature was misusing DMA_ATTR_NON_CONSISTENT. The patch revers both kernel and user space parts: removes the DMA

Hi Christoph, On Wed, Aug 19, 2020 at 8:56 AM Christoph Hellwig <hch at lst.de> wrote: > > The V4L2-FLAG-MEMORY-NON-CONSISTENT flag is entirely unused, Could you explain what makes you think it's unused? It's a feature of the UAPI generally supported by the videobuf2 framework and relied on by Chromium OS to get any kind of reasonable performance when accessing V4L2 buffers

The V4L2-FLAG-MEMORY-NON-CONSISTENT flag is entirely unused, and causes weird gymanstics with the DMA_ATTR_NON_CONSISTENT flag, which is unimplemented except on PARISC and some MIPS configs, and about to be removed. Signed-off-by: Christoph Hellwig <hch at lst.de> --- .../userspace-api/media/v4l/buffer.rst | 17 --------- .../media/v4l/vidioc-reqbufs.rst | 1 -

Hi Tomasz, On 2020-08-19 12:16, Tomasz Figa wrote: > Hi Christoph, > > On Wed, Aug 19, 2020 at 8:56 AM Christoph Hellwig <hch at lst.de> wrote: >> >> The V4L2-FLAG-MEMORY-NON-CONSISTENT flag is entirely unused, > > Could you explain what makes you think it's unused? It's a feature of > the UAPI generally supported by the videobuf2 framework and relied

On Wed, Aug 19, 2020 at 1:51 PM Robin Murphy <robin.murphy at arm.com> wrote: > > Hi Tomasz, > > On 2020-08-19 12:16, Tomasz Figa wrote: > > Hi Christoph, > > > > On Wed, Aug 19, 2020 at 8:56 AM Christoph Hellwig <hch at lst.de> wrote: > >> > >> The V4L2-FLAG-MEMORY-NON-CONSISTENT flag is entirely unused, > > > > Could you

Hi all, this series replaced the DMA_ATTR_NON_CONSISTENT flag to dma_alloc_attrs with a separate new dma_alloc_pages API, which is available on all platforms. In addition to cleaning up the convoluted code path, this ensures that other drivers that have asked for better support for non-coherent DMA to pages with incurring bounce buffering over can finally be properly supported. I'm still a

Hi all, this series replaced the DMA_ATTR_NON_CONSISTENT flag to dma_alloc_attrs with a separate new dma_alloc_pages API, which is available on all platforms. In addition to cleaning up the convoluted code path, this ensures that other drivers that have asked for better support for non-coherent DMA to pages with incurring bounce buffering over can finally be properly supported. As a follow up I

Hi all, this series replaced the DMA_ATTR_NON_CONSISTENT flag to dma_alloc_attrs with a separate new dma_alloc_pages API, which is available on all platforms. In addition to cleaning up the convoluted code path, this ensures that other drivers that have asked for better support for non-coherent DMA to pages with incurring bounce buffering over can finally be properly supported. I'm still a