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Wed, 25 Nov 2020 21:30:24 +0000 (GMT) Subject: Re: [PATCH v2 5/6] media: uvcvideo: Use dma_alloc_noncontiguos API To: Ricardo Ribalda , Robin Murphy , Christoph Hellwig , auro Carvalho Chehab , IOMMU DRIVERS , Joerg Roedel , Linux Doc Mailing List , Linux Kernel Mailing List , Linux Media Mailing List , Tomasz Figa , Sergey Senozhatsky From: Marek Szyprowski Message-ID: <527e4b4e-e631-adfa-e4fa-c777af82ae17@samsung.com> Date: Wed, 25 Nov 2020 22:30:28 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.5.0 MIME-Version: 1.0 In-Reply-To: <20201125203114.130967-1-ribalda@chromium.org> Content-Transfer-Encoding: 7bit Content-Language: en-US X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFjrIKsWRmVeSWpSXmKPExsWy7djPc7qfzuyLN9hxSthi5eqjTBYL9ltb dM7ewG6xsG0Ji8XlXXPYLHo2bGW1WLbpD5NF0/SDbBYHPzxhtVjwdRWjxefWf2wO3B5PDs5j 8lgzbw2jx+yGiyweCzaVemxa1cnmMfnGckaP3Tcb2Dw+b5IL4IjisklJzcksSy3St0vgyljU +JulYJ5+xarzcxkbGPepdjFyckgImEjsXDaPpYuRi0NIYAWjxOYjc1ghnC+MEnPmdTJBOJ8Z JQ7fO8wO03Jl2lM2iMRyRokrk39A9b9nlGicvYUNpEpYwFvixbaFYLNEBN4zS3S0ngVrZxMw lOh62wVWxCtgJ/H+9xkwm0VAVeLj6cfMILaoQJLEwY8PoGoEJU7OfMICYnMKWEucWf2TEcRm FpCX2P52DjOELS5x68l8sFslBP5zSKxse8QEcauLRPPOo6wQtrDEq+NboH6Qkfi/E6ahmVHi 4bm17BBOD6PE5aYZjBBV1hJ3zv0COoMDaIWmxPpd+hBhR4lV95Yyg4QlBPgkbrwVhDiCT2LS tulQYV6JjjYhiGo1iVnH18GtPXjhEjOE7SHRu20W2wRGxVlI3pyF5LVZSF6bhXDDAkaWVYzi qaXFuempxYZ5qeV6xYm5xaV56XrJ+bmbGIGp7PS/4592MM599VHvECMTB+MhRgkOZiURXnfh vfFCvCmJlVWpRfnxRaU5qcWHGKU5WJTEeVfNXhMvJJCeWJKanZpakFoEk2Xi4JRqYJK401Rb treRq0LmXOF+3oAH3/epG77rDWeu+HSP/9+uyT8i/gTssGM7HjFjcV+/vFiBipTiJIHq8Pzp azQlVcwN5RtP63BemGWcVvip8OU+jmufJaL6v7I/eHqe8djK1Hyuqexrr75U1XvgUKD4/e7/ b4mMs9z+avCtf3dT426Erac6+7q2zjP8Kz0sl2fdMlf6PJfhz6QAywVn/jZs6Kqa++/VrDDW NOeZojsa5z5ev2y3xudpfox3vjkeUfWuyT9pvd+5MOPHLQOHqh69vYmXq5Zz/Niv/ODmfl2O dSKLDx6/5t7xVmHyj6B10Rl/GSJ4FhWy5X++0hp9/uF7NiHBu1GFd3azN31L/+EY2KnEUpyR aKjFXFScCABr1rVW1AMAAA== X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFjrGIsWRmVeSWpSXmKPExsVy+t/xu7ofz+yLNzhyhd9i5eqjTBYL9ltb dM7ewG6xsG0Ji8XlXXPYLHo2bGW1WLbpD5NF0/SDbBYHPzxhtVjwdRWjxefWf2wO3B5PDs5j 8lgzbw2jx+yGiyweCzaVemxa1cnmMfnGckaP3Tcb2Dw+b5IL4IjSsynKLy1JVcjILy6xVYo2 tDDSM7S00DMysdQzNDaPtTIyVdK3s0lJzcksSy3St0vQy1jU+JulYJ5+xarzcxkbGPepdjFy ckgImEhcmfaUrYuRi0NIYCmjREfbamaIhIzEyWkNrBC2sMSfa11QRW8ZJc41NTOBJIQFvCVe bFvICpIQEfjILPHj8yuwbiGBPkaJxz88QGw2AUOJrrcg3ZwcvAJ2Eu9/nwGzWQRUJT6efgxW LyqQJPF76VqoGkGJkzOfsIDYnALWEmdW/2QEsZkFzCTmbX7IDGHLS2x/OwfKFpe49WQ+0wRG wVlI2mchaZmFpGUWkpYFjCyrGEVSS4tz03OLjfSKE3OLS/PS9ZLzczcxAiN027GfW3Ywrnz1 Ue8QIxMH4yFGCQ5mJRFed+G98UK8KYmVValF+fFFpTmpxYcYTYH+mcgsJZqcD0wReSXxhmYG poYmZpYGppZmxkrivCZH1sQLCaQnlqRmp6YWpBbB9DFxcEo1MO2NNwvpVTzfHaYqeDN7ZYjF k9KI6z6vj7Qsm22SGxUpZKlwoN81+J8f67QJVbe7RHy4dmdo2d0KMVrz2uxsZcXBXfvvTitZ u1Bs78bU9RVZr7kj7R1Cmb8Hej8WuLLefg+Dj95Sq86MTpHj22pDe+d/MtAVv/Cnj/kUw7cc u7LJqpLNf2U650x6uPLulrm3LBNfMEdes9jlMEltt3wJy1d29tj04kmhlvFlt+y/7paSWHBA 7MCqepn01mvhe93avVoXrj/MXbpps0LuyRmH+mzP7OlRvvX2FZfvskPbD0cvXi6/O2+zrvLS yVorbBieLtYMuXY80FEp1jzt+US9YOnSK4KnlErvb9oQlGThpsRSnJFoqMVcVJwIADxDY4ZZ AwAA X-CMS-MailID: 20201125213025eucas1p24fd0cb6e4383297f8527b2075ce3e4ea X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" X-RootMTR: 20201125203125eucas1p1456f09a6d130e2f015707b4e5f9dbfc1 X-EPHeader: CA CMS-TYPE: 201P X-CMS-RootMailID: 20201125203125eucas1p1456f09a6d130e2f015707b4e5f9dbfc1 References: <20201125203114.130967-1-ribalda@chromium.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi On 25.11.2020 21:31, 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_sg(). > > 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 > --- > > v2: Thanks to Robin! > > Use dma_sync_sg instead of dma_sync_single > > > drivers/media/usb/uvc/uvc_video.c | 83 ++++++++++++++++++++++++++----- > drivers/media/usb/uvc/uvcvideo.h | 2 + > 2 files changed, 73 insertions(+), 12 deletions(-) > > diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c > index a6a441d92b94..b2e6a9522999 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 +1544,10 @@ 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_sg_for_cpu(stream_to_dmadev(stream), uvc_urb->sgt.sgl, > + uvc_urb->sgt.nents, DMA_FROM_DEVICE); Please use dma_sync_sgtable_for_cpu(stream_to_dmadev(stream), &uvc_urb->sgt, DMA_FROM_DEVICE); I also think that there should be a call to dma_sync_sgtable_for_device() before starting the potential DMA transfer. Just to make sure that CPU wont trash the newly captured data and for the API completeness. > + } > stream->decode(uvc_urb, buf, buf_meta); > > /* If no async work is needed, resubmit the URB immediately. */ > @@ -1566,8 +1575,16 @@ 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) { > + sg_free_table(&uvc_urb->sgt); > + 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 +1594,56 @@ 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; > + } > + > + if (sg_alloc_table_from_pages(&uvc_urb->sgt, uvc_urb->pages, > + PAGE_ALIGN(stream->urb_size) >> PAGE_SHIFT, 0, > + stream->urb_size, GFP_KERNEL)) { > + vunmap(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 +1674,11 @@ 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 a3dfacf069c4..3e6618a2ac82 100644 > --- a/drivers/media/usb/uvc/uvcvideo.h > +++ b/drivers/media/usb/uvc/uvcvideo.h > @@ -532,6 +532,8 @@ struct uvc_urb { > > char *buffer; > dma_addr_t dma; > + struct page **pages; > + struct sg_table sgt; > > unsigned int async_operations; > struct uvc_copy_op copy_operations[UVC_MAX_PACKETS]; Best regards -- Marek Szyprowski, PhD Samsung R&D Institute Poland