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 <riba...@chromium.org> --- This patch depends on dma_alloc_contiguous API1315351diffmboxseries https://lore.kernel.org/patchwork/patch/1315351/#1535182 drivers/media/usb/uvc/uvc_video.c | 69 +++++++++++++++++++++++++------ drivers/media/usb/uvc/uvcvideo.h | 1 + 2 files changed, 58 insertions(+), 12 deletions(-) diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c index ff624bb857d3..ef1b029b8576 100644 --- a/drivers/media/usb/uvc/uvc_video.c +++ b/drivers/media/usb/uvc/uvc_video.c @@ -1641,6 +1641,11 @@ 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; @@ -1693,6 +1698,11 @@ 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. */ @@ -1723,8 +1733,15 @@ 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 @@ -1734,6 +1751,42 @@ 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, &uvc_urb->dma); + return uvc_urb->buffer != NULL; + } + + uvc_urb->pages = dma_alloc_noncontiguous(dma_dev, stream->urb_size, + &uvc_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 @@ -1764,19 +1817,11 @@ 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 = &stream->uvc_urb[i]; - stream->urb_size = psize * npackets; -#ifndef CONFIG_DMA_NONCOHERENT - uvc_urb->buffer = usb_alloc_coherent( - stream->dev->udev, stream->urb_size, - gfp_flags | __GFP_NOWARN, &uvc_urb->dma); -#else - uvc_urb->buffer = - kmalloc(stream->urb_size, gfp_flags | __GFP_NOWARN); -#endif - if (!uvc_urb->buffer) { + if (!uvc_alloc_urb_buffer(stream, uvc_urb, gfp_flags)) { uvc_free_urb_buffers(stream); break; } diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h index 60d830d74ac1..80eeeaf3cd06 100644 --- a/drivers/media/usb/uvc/uvcvideo.h +++ b/drivers/media/usb/uvc/uvcvideo.h @@ -544,6 +544,7 @@ struct uvc_urb { char *buffer; dma_addr_t dma; + struct page **pages; unsigned int async_operations; struct uvc_copy_op copy_operations[UVC_MAX_PACKETS]; -- 2.29.2.299.gdc1121823c-goog
