Re: [PATCH 5/6] media: uvcvideo: Use dma_alloc_noncontiguos API
Hi Robin On Tue, Nov 24, 2020 at 5:29 PM Robin Murphy wrote: > > On 2020-11-24 15:38, Ricardo Ribalda wrote: > > On architectures where the is no coherent caching such as ARM use the > > dma_alloc_noncontiguos API and handle manually the cache flushing using > > dma_sync_single(). > > > > With this patch on the affected architectures we can measure up to 20x > > performance improvement in uvc_video_copy_data_work(). > > > > Signed-off-by: Ricardo Ribalda > > --- > > drivers/media/usb/uvc/uvc_video.c | 74 ++- > > drivers/media/usb/uvc/uvcvideo.h | 1 + > > 2 files changed, 63 insertions(+), 12 deletions(-) > > > > diff --git a/drivers/media/usb/uvc/uvc_video.c > > b/drivers/media/usb/uvc/uvc_video.c > > index a6a441d92b94..9e90b261428a 100644 > > --- a/drivers/media/usb/uvc/uvc_video.c > > +++ b/drivers/media/usb/uvc/uvc_video.c > > @@ -1490,6 +1490,11 @@ static void uvc_video_encode_bulk(struct uvc_urb > > *uvc_urb, > > urb->transfer_buffer_length = stream->urb_size - len; > > } > > > > +static inline struct device *stream_to_dmadev(struct uvc_streaming *stream) > > +{ > > + return stream->dev->udev->bus->controller->parent; > > +} > > + > > static void uvc_video_complete(struct urb *urb) > > { > > struct uvc_urb *uvc_urb = urb->context; > > @@ -1539,6 +1544,11 @@ static void uvc_video_complete(struct urb *urb) > >* Process the URB headers, and optionally queue expensive memcpy > > tasks > >* to be deferred to a work queue. > >*/ > > + if (uvc_urb->pages) > > + dma_sync_single_for_cpu(stream_to_dmadev(stream), > > + urb->transfer_dma, > > + urb->transfer_buffer_length, > > + DMA_FROM_DEVICE); > > This doesn't work. Even in iommu-dma, the streaming API still expects to > work on physically-contiguous memory that could have been passed to > dma_map_single() in the first place. As-is, this will invalidate > transfer_buffer_length bytes from the start of the *first* physical > page, and thus destroy random other data if lines from subsequent > unrelated pages are dirty in caches. > > The only feasible way to do a DMA sync on disjoint pages in a single > call is with a scatterlist. Thanks for pointing this out. I guess I was lucky on my hardware and the areas were always contiguous. Will rework and send back to the list. Thanks again. > > Robin. > > > stream->decode(uvc_urb, buf, buf_meta); > > > > /* If no async work is needed, resubmit the URB immediately. */ > > @@ -1566,8 +1576,15 @@ static void uvc_free_urb_buffers(struct > > uvc_streaming *stream) > > continue; > > > > #ifndef CONFIG_DMA_NONCOHERENT > > - usb_free_coherent(stream->dev->udev, stream->urb_size, > > - uvc_urb->buffer, uvc_urb->dma); > > + if (uvc_urb->pages) { > > + vunmap(uvc_urb->buffer); > > + dma_free_noncontiguous(stream_to_dmadev(stream), > > +stream->urb_size, > > +uvc_urb->pages, uvc_urb->dma); > > + } else { > > + usb_free_coherent(stream->dev->udev, stream->urb_size, > > + uvc_urb->buffer, uvc_urb->dma); > > + } > > #else > > kfree(uvc_urb->buffer); > > #endif > > @@ -1577,6 +1594,47 @@ static void uvc_free_urb_buffers(struct > > uvc_streaming *stream) > > stream->urb_size = 0; > > } > > > > +#ifndef CONFIG_DMA_NONCOHERENT > > +static bool uvc_alloc_urb_buffer(struct uvc_streaming *stream, > > + struct uvc_urb *uvc_urb, gfp_t gfp_flags) > > +{ > > + struct device *dma_dev = dma_dev = stream_to_dmadev(stream); > > + > > + if (!dma_can_alloc_noncontiguous(dma_dev)) { > > + uvc_urb->buffer = usb_alloc_coherent(stream->dev->udev, > > + stream->urb_size, > > + gfp_flags | __GFP_NOWARN, > > + _urb->dma); > > + return uvc_urb->buffer != NULL; > > + } > > + > > + uvc_urb->pages = dma_alloc_noncontiguous(dma_dev, stream->urb_size, > > + _urb->dma, > > + gfp_flags | __GFP_NOWARN, 0); > > + if (!uvc_urb->pages) > > + return false; > > + > > + uvc_urb->buffer = vmap(uvc_urb->pages, > > +PAGE_ALIGN(stream->urb_size) >> PAGE_SHIFT, > > +VM_DMA_COHERENT, PAGE_KERNEL); > > + if (!uvc_urb->buffer) { > > + dma_free_noncontiguous(dma_dev, stream->urb_size, > > +uvc_urb->pages,
Re: [PATCH 5/6] media: uvcvideo: Use dma_alloc_noncontiguos API
On 2020-11-24 15:38, Ricardo Ribalda wrote: On architectures where the is no coherent caching such as ARM use the dma_alloc_noncontiguos API and handle manually the cache flushing using dma_sync_single(). With this patch on the affected architectures we can measure up to 20x performance improvement in uvc_video_copy_data_work(). Signed-off-by: Ricardo Ribalda --- drivers/media/usb/uvc/uvc_video.c | 74 ++- drivers/media/usb/uvc/uvcvideo.h | 1 + 2 files changed, 63 insertions(+), 12 deletions(-) diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c index a6a441d92b94..9e90b261428a 100644 --- a/drivers/media/usb/uvc/uvc_video.c +++ b/drivers/media/usb/uvc/uvc_video.c @@ -1490,6 +1490,11 @@ static void uvc_video_encode_bulk(struct uvc_urb *uvc_urb, urb->transfer_buffer_length = stream->urb_size - len; } +static inline struct device *stream_to_dmadev(struct uvc_streaming *stream) +{ + return stream->dev->udev->bus->controller->parent; +} + static void uvc_video_complete(struct urb *urb) { struct uvc_urb *uvc_urb = urb->context; @@ -1539,6 +1544,11 @@ static void uvc_video_complete(struct urb *urb) * Process the URB headers, and optionally queue expensive memcpy tasks * to be deferred to a work queue. */ + if (uvc_urb->pages) + dma_sync_single_for_cpu(stream_to_dmadev(stream), + urb->transfer_dma, + urb->transfer_buffer_length, + DMA_FROM_DEVICE); This doesn't work. Even in iommu-dma, the streaming API still expects to work on physically-contiguous memory that could have been passed to dma_map_single() in the first place. As-is, this will invalidate transfer_buffer_length bytes from the start of the *first* physical page, and thus destroy random other data if lines from subsequent unrelated pages are dirty in caches. The only feasible way to do a DMA sync on disjoint pages in a single call is with a scatterlist. Robin. stream->decode(uvc_urb, buf, buf_meta); /* If no async work is needed, resubmit the URB immediately. */ @@ -1566,8 +1576,15 @@ static void uvc_free_urb_buffers(struct uvc_streaming *stream) continue; #ifndef CONFIG_DMA_NONCOHERENT - usb_free_coherent(stream->dev->udev, stream->urb_size, - uvc_urb->buffer, uvc_urb->dma); + if (uvc_urb->pages) { + vunmap(uvc_urb->buffer); + dma_free_noncontiguous(stream_to_dmadev(stream), + stream->urb_size, + uvc_urb->pages, uvc_urb->dma); + } else { + usb_free_coherent(stream->dev->udev, stream->urb_size, + uvc_urb->buffer, uvc_urb->dma); + } #else kfree(uvc_urb->buffer); #endif @@ -1577,6 +1594,47 @@ static void uvc_free_urb_buffers(struct uvc_streaming *stream) stream->urb_size = 0; } +#ifndef CONFIG_DMA_NONCOHERENT +static bool uvc_alloc_urb_buffer(struct uvc_streaming *stream, +struct uvc_urb *uvc_urb, gfp_t gfp_flags) +{ + struct device *dma_dev = dma_dev = stream_to_dmadev(stream); + + if (!dma_can_alloc_noncontiguous(dma_dev)) { + uvc_urb->buffer = usb_alloc_coherent(stream->dev->udev, +stream->urb_size, +gfp_flags | __GFP_NOWARN, +_urb->dma); + return uvc_urb->buffer != NULL; + } + + uvc_urb->pages = dma_alloc_noncontiguous(dma_dev, stream->urb_size, +_urb->dma, +gfp_flags | __GFP_NOWARN, 0); + if (!uvc_urb->pages) + return false; + + uvc_urb->buffer = vmap(uvc_urb->pages, + PAGE_ALIGN(stream->urb_size) >> PAGE_SHIFT, + VM_DMA_COHERENT, PAGE_KERNEL); + if (!uvc_urb->buffer) { + dma_free_noncontiguous(dma_dev, stream->urb_size, + uvc_urb->pages, uvc_urb->dma); + return false; + } + + return true; +} +#else +static bool uvc_alloc_urb_buffer(struct uvc_streaming *stream, +struct uvc_urb *uvc_urb, gfp_t gfp_flags) +{ + uvc_urb->buffer = kmalloc(stream->urb_size, gfp_flags | __GFP_NOWARN); + + return uvc_urb->buffer != NULL; +} +#endif + /* * Allocate transfer buffers. This function can be called with buffers * already allocated when resuming from suspend, in which case it will @@
[PATCH 5/6] media: uvcvideo: Use dma_alloc_noncontiguos API
On architectures where the is no coherent caching such as ARM use the dma_alloc_noncontiguos API and handle manually the cache flushing using dma_sync_single(). With this patch on the affected architectures we can measure up to 20x performance improvement in uvc_video_copy_data_work(). Signed-off-by: Ricardo Ribalda --- drivers/media/usb/uvc/uvc_video.c | 74 ++- drivers/media/usb/uvc/uvcvideo.h | 1 + 2 files changed, 63 insertions(+), 12 deletions(-) diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c index a6a441d92b94..9e90b261428a 100644 --- a/drivers/media/usb/uvc/uvc_video.c +++ b/drivers/media/usb/uvc/uvc_video.c @@ -1490,6 +1490,11 @@ static void uvc_video_encode_bulk(struct uvc_urb *uvc_urb, urb->transfer_buffer_length = stream->urb_size - len; } +static inline struct device *stream_to_dmadev(struct uvc_streaming *stream) +{ + return stream->dev->udev->bus->controller->parent; +} + static void uvc_video_complete(struct urb *urb) { struct uvc_urb *uvc_urb = urb->context; @@ -1539,6 +1544,11 @@ static void uvc_video_complete(struct urb *urb) * Process the URB headers, and optionally queue expensive memcpy tasks * to be deferred to a work queue. */ + if (uvc_urb->pages) + dma_sync_single_for_cpu(stream_to_dmadev(stream), + urb->transfer_dma, + urb->transfer_buffer_length, + DMA_FROM_DEVICE); stream->decode(uvc_urb, buf, buf_meta); /* If no async work is needed, resubmit the URB immediately. */ @@ -1566,8 +1576,15 @@ static void uvc_free_urb_buffers(struct uvc_streaming *stream) continue; #ifndef CONFIG_DMA_NONCOHERENT - usb_free_coherent(stream->dev->udev, stream->urb_size, - uvc_urb->buffer, uvc_urb->dma); + if (uvc_urb->pages) { + vunmap(uvc_urb->buffer); + dma_free_noncontiguous(stream_to_dmadev(stream), + stream->urb_size, + uvc_urb->pages, uvc_urb->dma); + } else { + usb_free_coherent(stream->dev->udev, stream->urb_size, + uvc_urb->buffer, uvc_urb->dma); + } #else kfree(uvc_urb->buffer); #endif @@ -1577,6 +1594,47 @@ static void uvc_free_urb_buffers(struct uvc_streaming *stream) stream->urb_size = 0; } +#ifndef CONFIG_DMA_NONCOHERENT +static bool uvc_alloc_urb_buffer(struct uvc_streaming *stream, +struct uvc_urb *uvc_urb, gfp_t gfp_flags) +{ + struct device *dma_dev = dma_dev = stream_to_dmadev(stream); + + if (!dma_can_alloc_noncontiguous(dma_dev)) { + uvc_urb->buffer = usb_alloc_coherent(stream->dev->udev, +stream->urb_size, +gfp_flags | __GFP_NOWARN, +_urb->dma); + return uvc_urb->buffer != NULL; + } + + uvc_urb->pages = dma_alloc_noncontiguous(dma_dev, stream->urb_size, +_urb->dma, +gfp_flags | __GFP_NOWARN, 0); + if (!uvc_urb->pages) + return false; + + uvc_urb->buffer = vmap(uvc_urb->pages, + PAGE_ALIGN(stream->urb_size) >> PAGE_SHIFT, + VM_DMA_COHERENT, PAGE_KERNEL); + if (!uvc_urb->buffer) { + dma_free_noncontiguous(dma_dev, stream->urb_size, + uvc_urb->pages, uvc_urb->dma); + return false; + } + + return true; +} +#else +static bool uvc_alloc_urb_buffer(struct uvc_streaming *stream, +struct uvc_urb *uvc_urb, gfp_t gfp_flags) +{ + uvc_urb->buffer = kmalloc(stream->urb_size, gfp_flags | __GFP_NOWARN); + + return uvc_urb->buffer != NULL; +} +#endif + /* * Allocate transfer buffers. This function can be called with buffers * already allocated when resuming from suspend, in which case it will @@ -1607,19 +1665,11 @@ static int uvc_alloc_urb_buffers(struct uvc_streaming *stream, /* Retry allocations until one succeed. */ for (; npackets > 1; npackets /= 2) { + stream->urb_size = psize * npackets; for (i = 0; i < UVC_URBS; ++i) { struct uvc_urb *uvc_urb = >uvc_urb[i]; - stream->urb_size = psize * npackets; -#ifndef CONFIG_DMA_NONCOHERENT - uvc_urb->buffer = usb_alloc_coherent( - stream->dev->udev,