Hi Hans,

Thank you for the patch.

On Tuesday 18 November 2014 13:51:01 Hans Verkuil wrote:
> From: Hans Verkuil <hans.verk...@cisco.com>
> 
> Require that dma-sg also uses an allocation context. This is in preparation
> for adding prepare/finish memops to sync the memory between DMA and CPU.

I think this has been raised before, but given that our allocation contexts 
just hold a struct device pointer, wouldn't it be simpler to just pass it 
explicitly when creating the queue ? Do we have use cases for using different 
struct device instances per plane ?

> Signed-off-by: Hans Verkuil <hans.verk...@cisco.com>
> ---
>  drivers/media/pci/cx23885/cx23885-417.c         |  1 +
>  drivers/media/pci/cx23885/cx23885-core.c        | 10 +++++++-
>  drivers/media/pci/cx23885/cx23885-dvb.c         |  1 +
>  drivers/media/pci/cx23885/cx23885-vbi.c         |  1 +
>  drivers/media/pci/cx23885/cx23885-video.c       |  1 +
>  drivers/media/pci/cx23885/cx23885.h             |  1 +
>  drivers/media/pci/saa7134/saa7134-core.c        | 18 ++++++++++----
>  drivers/media/pci/saa7134/saa7134-ts.c          |  1 +
>  drivers/media/pci/saa7134/saa7134-vbi.c         |  1 +
>  drivers/media/pci/saa7134/saa7134-video.c       |  1 +
>  drivers/media/pci/saa7134/saa7134.h             |  1 +
>  drivers/media/pci/solo6x10/solo6x10-v4l2-enc.c  | 10 ++++++++
>  drivers/media/pci/solo6x10/solo6x10.h           |  1 +
>  drivers/media/pci/tw68/tw68-core.c              | 15 +++++++++---
>  drivers/media/pci/tw68/tw68-video.c             |  1 +
>  drivers/media/pci/tw68/tw68.h                   |  1 +
>  drivers/media/platform/marvell-ccic/mcam-core.c | 13 +++++++++-
>  drivers/media/platform/marvell-ccic/mcam-core.h |  1 +
>  drivers/media/v4l2-core/videobuf2-dma-sg.c      | 32 ++++++++++++++++++++++
>  include/media/videobuf2-dma-sg.h                |  3 +++
>  20 files changed, 104 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/media/pci/cx23885/cx23885-417.c
> b/drivers/media/pci/cx23885/cx23885-417.c index 3948db3..d72a3ec 100644
> --- a/drivers/media/pci/cx23885/cx23885-417.c
> +++ b/drivers/media/pci/cx23885/cx23885-417.c
> @@ -1148,6 +1148,7 @@ static int queue_setup(struct vb2_queue *q, const
> struct v4l2_format *fmt, dev->ts1.ts_packet_count = mpeglines;
>       *num_planes = 1;
>       sizes[0] = mpeglinesize * mpeglines;
> +     alloc_ctxs[0] = dev->alloc_ctx;
>       *num_buffers = mpegbufs;
>       return 0;
>  }
> diff --git a/drivers/media/pci/cx23885/cx23885-core.c
> b/drivers/media/pci/cx23885/cx23885-core.c index 331edda..d452b5c 100644
> --- a/drivers/media/pci/cx23885/cx23885-core.c
> +++ b/drivers/media/pci/cx23885/cx23885-core.c
> @@ -1997,9 +1997,14 @@ static int cx23885_initdev(struct pci_dev *pci_dev,
>       if (!pci_dma_supported(pci_dev, 0xffffffff)) {
>               printk("%s/0: Oops: no 32bit PCI DMA ???\n", dev->name);
>               err = -EIO;
> -             goto fail_irq;
> +             goto fail_context;
>       }
> 
> +     dev->alloc_ctx = vb2_dma_sg_init_ctx(&pci_dev->dev);
> +     if (IS_ERR(dev->alloc_ctx)) {
> +             err = PTR_ERR(dev->alloc_ctx);
> +             goto fail_context;
> +     }
>       err = request_irq(pci_dev->irq, cx23885_irq,
>                         IRQF_SHARED, dev->name, dev);
>       if (err < 0) {
> @@ -2028,6 +2033,8 @@ static int cx23885_initdev(struct pci_dev *pci_dev,
>       return 0;
> 
>  fail_irq:
> +     vb2_dma_sg_cleanup_ctx(dev->alloc_ctx);
> +fail_context:
>       cx23885_dev_unregister(dev);
>  fail_ctrl:
>       v4l2_ctrl_handler_free(hdl);
> @@ -2053,6 +2060,7 @@ static void cx23885_finidev(struct pci_dev *pci_dev)
>       free_irq(pci_dev->irq, dev);
> 
>       cx23885_dev_unregister(dev);
> +     vb2_dma_sg_cleanup_ctx(dev->alloc_ctx);
>       v4l2_ctrl_handler_free(&dev->ctrl_handler);
>       v4l2_device_unregister(v4l2_dev);
>       kfree(dev);
> diff --git a/drivers/media/pci/cx23885/cx23885-dvb.c
> b/drivers/media/pci/cx23885/cx23885-dvb.c index 1ed92ee..44fafba 100644
> --- a/drivers/media/pci/cx23885/cx23885-dvb.c
> +++ b/drivers/media/pci/cx23885/cx23885-dvb.c
> @@ -102,6 +102,7 @@ static int queue_setup(struct vb2_queue *q, const struct
> v4l2_format *fmt, port->ts_packet_count = 32;
>       *num_planes = 1;
>       sizes[0] = port->ts_packet_size * port->ts_packet_count;
> +     alloc_ctxs[0] = port->dev->alloc_ctx;
>       *num_buffers = 32;
>       return 0;
>  }
> diff --git a/drivers/media/pci/cx23885/cx23885-vbi.c
> b/drivers/media/pci/cx23885/cx23885-vbi.c index a7c6ef8..1d339a6 100644
> --- a/drivers/media/pci/cx23885/cx23885-vbi.c
> +++ b/drivers/media/pci/cx23885/cx23885-vbi.c
> @@ -132,6 +132,7 @@ static int queue_setup(struct vb2_queue *q, const struct
> v4l2_format *fmt, lines = VBI_NTSC_LINE_COUNT;
>       *num_planes = 1;
>       sizes[0] = lines * VBI_LINE_LENGTH * 2;
> +     alloc_ctxs[0] = dev->alloc_ctx;
>       return 0;
>  }
> 
> diff --git a/drivers/media/pci/cx23885/cx23885-video.c
> b/drivers/media/pci/cx23885/cx23885-video.c index 091f5db..371eecf 100644
> --- a/drivers/media/pci/cx23885/cx23885-video.c
> +++ b/drivers/media/pci/cx23885/cx23885-video.c
> @@ -323,6 +323,7 @@ static int queue_setup(struct vb2_queue *q, const struct
> v4l2_format *fmt,
> 
>       *num_planes = 1;
>       sizes[0] = (dev->fmt->depth * dev->width * dev->height) >> 3;
> +     alloc_ctxs[0] = dev->alloc_ctx;
>       return 0;
>  }
> 
> diff --git a/drivers/media/pci/cx23885/cx23885.h
> b/drivers/media/pci/cx23885/cx23885.h index cf4efa4..f55cd12 100644
> --- a/drivers/media/pci/cx23885/cx23885.h
> +++ b/drivers/media/pci/cx23885/cx23885.h
> @@ -425,6 +425,7 @@ struct cx23885_dev {
>       struct vb2_queue           vb2_vidq;
>       struct cx23885_dmaqueue    vbiq;
>       struct vb2_queue           vb2_vbiq;
> +     void                       *alloc_ctx;
> 
>       spinlock_t                 slock;
> 
> diff --git a/drivers/media/pci/saa7134/saa7134-core.c
> b/drivers/media/pci/saa7134/saa7134-core.c index 236ed72..a349e96 100644
> --- a/drivers/media/pci/saa7134/saa7134-core.c
> +++ b/drivers/media/pci/saa7134/saa7134-core.c
> @@ -1001,13 +1001,18 @@ static int saa7134_initdev(struct pci_dev *pci_dev,
>       saa7134_board_init1(dev);
>       saa7134_hwinit1(dev);
> 
> +     dev->alloc_ctx = vb2_dma_sg_init_ctx(&pci_dev->dev);
> +     if (IS_ERR(dev->alloc_ctx)) {
> +             err = PTR_ERR(dev->alloc_ctx);
> +             goto fail3;
> +     }
>       /* get irq */
>       err = request_irq(pci_dev->irq, saa7134_irq,
>                         IRQF_SHARED, dev->name, dev);
>       if (err < 0) {
>               printk(KERN_ERR "%s: can't get IRQ %d\n",
>                      dev->name,pci_dev->irq);
> -             goto fail3;
> +             goto fail4;
>       }
> 
>       /* wait a bit, register i2c bus */
> @@ -1065,7 +1070,7 @@ static int saa7134_initdev(struct pci_dev *pci_dev,
>       if (err < 0) {
>               printk(KERN_INFO "%s: can't register video device\n",
>                      dev->name);
> -             goto fail4;
> +             goto fail5;
>       }
>       printk(KERN_INFO "%s: registered device %s [v4l2]\n",
>              dev->name, video_device_node_name(dev->video_dev));
> @@ -1078,7 +1083,7 @@ static int saa7134_initdev(struct pci_dev *pci_dev,
>       err = video_register_device(dev->vbi_dev,VFL_TYPE_VBI,
>                                   vbi_nr[dev->nr]);
>       if (err < 0)
> -             goto fail4;
> +             goto fail5;
>       printk(KERN_INFO "%s: registered device %s\n",
>              dev->name, video_device_node_name(dev->vbi_dev));
> 
> @@ -1089,7 +1094,7 @@ static int saa7134_initdev(struct pci_dev *pci_dev,
>               err = video_register_device(dev->radio_dev,VFL_TYPE_RADIO,
>                                           radio_nr[dev->nr]);
>               if (err < 0)
> -                     goto fail4;
> +                     goto fail5;
>               printk(KERN_INFO "%s: registered device %s\n",
>                      dev->name, video_device_node_name(dev->radio_dev));
>       }
> @@ -1103,10 +1108,12 @@ static int saa7134_initdev(struct pci_dev *pci_dev,
>       request_submodules(dev);
>       return 0;
> 
> - fail4:
> + fail5:
>       saa7134_unregister_video(dev);
>       saa7134_i2c_unregister(dev);
>       free_irq(pci_dev->irq, dev);
> + fail4:
> +     vb2_dma_sg_cleanup_ctx(dev->alloc_ctx);
>   fail3:
>       saa7134_hwfini(dev);
>       iounmap(dev->lmmio);
> @@ -1173,6 +1180,7 @@ static void saa7134_finidev(struct pci_dev *pci_dev)
> 
>       /* release resources */
>       free_irq(pci_dev->irq, dev);
> +     vb2_dma_sg_cleanup_ctx(dev->alloc_ctx);
>       iounmap(dev->lmmio);
>       release_mem_region(pci_resource_start(pci_dev,0),
>                          pci_resource_len(pci_dev,0));
> diff --git a/drivers/media/pci/saa7134/saa7134-ts.c
> b/drivers/media/pci/saa7134/saa7134-ts.c index bd25323..8eff4a7 100644
> --- a/drivers/media/pci/saa7134/saa7134-ts.c
> +++ b/drivers/media/pci/saa7134/saa7134-ts.c
> @@ -142,6 +142,7 @@ int saa7134_ts_queue_setup(struct vb2_queue *q, const
> struct v4l2_format *fmt, *nbuffers = 3;
>       *nplanes = 1;
>       sizes[0] = size;
> +     alloc_ctxs[0] = dev->alloc_ctx;
>       return 0;
>  }
>  EXPORT_SYMBOL_GPL(saa7134_ts_queue_setup);
> diff --git a/drivers/media/pci/saa7134/saa7134-vbi.c
> b/drivers/media/pci/saa7134/saa7134-vbi.c index 4f0b101..e2cc684 100644
> --- a/drivers/media/pci/saa7134/saa7134-vbi.c
> +++ b/drivers/media/pci/saa7134/saa7134-vbi.c
> @@ -156,6 +156,7 @@ static int queue_setup(struct vb2_queue *q, const struct
> v4l2_format *fmt, *nbuffers = saa7134_buffer_count(size, *nbuffers);
>       *nplanes = 1;
>       sizes[0] = size;
> +     alloc_ctxs[0] = dev->alloc_ctx;
>       return 0;
>  }
> 
> diff --git a/drivers/media/pci/saa7134/saa7134-video.c
> b/drivers/media/pci/saa7134/saa7134-video.c index fc4a427..ba02995 100644
> --- a/drivers/media/pci/saa7134/saa7134-video.c
> +++ b/drivers/media/pci/saa7134/saa7134-video.c
> @@ -932,6 +932,7 @@ static int queue_setup(struct vb2_queue *q, const struct
> v4l2_format *fmt, *nbuffers = saa7134_buffer_count(size, *nbuffers);
>       *nplanes = 1;
>       sizes[0] = size;
> +     alloc_ctxs[0] = dev->alloc_ctx;
>       return 0;
>  }
> 
> diff --git a/drivers/media/pci/saa7134/saa7134.h
> b/drivers/media/pci/saa7134/saa7134.h index 1a82dd0..c644c7d 100644
> --- a/drivers/media/pci/saa7134/saa7134.h
> +++ b/drivers/media/pci/saa7134/saa7134.h
> @@ -588,6 +588,7 @@ struct saa7134_dev {
> 
> 
>       /* video+ts+vbi capture */
> +     void                       *alloc_ctx;
>       struct saa7134_dmaqueue    video_q;
>       struct vb2_queue           video_vbq;
>       struct saa7134_dmaqueue    vbi_q;
> diff --git a/drivers/media/pci/solo6x10/solo6x10-v4l2-enc.c
> b/drivers/media/pci/solo6x10/solo6x10-v4l2-enc.c index 30e09d9..4f6bfba
> 100644
> --- a/drivers/media/pci/solo6x10/solo6x10-v4l2-enc.c
> +++ b/drivers/media/pci/solo6x10/solo6x10-v4l2-enc.c
> @@ -718,7 +718,10 @@ static int solo_enc_queue_setup(struct vb2_queue *q,
>                               unsigned int *num_planes, unsigned int sizes[],
>                               void *alloc_ctxs[])
>  {
> +     struct solo_enc_dev *solo_enc = vb2_get_drv_priv(q);
> +
>       sizes[0] = FRAME_BUF_SIZE;
> +     alloc_ctxs[0] = solo_enc->alloc_ctx;
>       *num_planes = 1;
> 
>       if (*num_buffers < MIN_VID_BUFFERS)
> @@ -1266,6 +1269,11 @@ static struct solo_enc_dev *solo_enc_alloc(struct
> solo_dev *solo_dev, return ERR_PTR(-ENOMEM);
> 
>       hdl = &solo_enc->hdl;
> +     solo_enc->alloc_ctx = vb2_dma_sg_init_ctx(&solo_dev->pdev->dev);
> +     if (IS_ERR(solo_enc->alloc_ctx)) {
> +             ret = PTR_ERR(solo_enc->alloc_ctx);
> +             goto hdl_free;
> +     }
>       v4l2_ctrl_handler_init(hdl, 10);
>       v4l2_ctrl_new_std(hdl, &solo_ctrl_ops,
>                       V4L2_CID_BRIGHTNESS, 0, 255, 1, 128);
> @@ -1369,6 +1377,7 @@ pci_free:
>                       solo_enc->desc_items, solo_enc->desc_dma);
>  hdl_free:
>       v4l2_ctrl_handler_free(hdl);
> +     vb2_dma_sg_cleanup_ctx(solo_enc->alloc_ctx);
>       kfree(solo_enc);
>       return ERR_PTR(ret);
>  }
> @@ -1383,6 +1392,7 @@ static void solo_enc_free(struct solo_enc_dev
> *solo_enc) solo_enc->desc_items, solo_enc->desc_dma);
>       video_unregister_device(solo_enc->vfd);
>       v4l2_ctrl_handler_free(&solo_enc->hdl);
> +     vb2_dma_sg_cleanup_ctx(solo_enc->alloc_ctx);
>       kfree(solo_enc);
>  }
> 
> diff --git a/drivers/media/pci/solo6x10/solo6x10.h
> b/drivers/media/pci/solo6x10/solo6x10.h index 72017b7..bd8edfa 100644
> --- a/drivers/media/pci/solo6x10/solo6x10.h
> +++ b/drivers/media/pci/solo6x10/solo6x10.h
> @@ -180,6 +180,7 @@ struct solo_enc_dev {
>       u32                     sequence;
>       struct vb2_queue        vidq;
>       struct list_head        vidq_active;
> +     void                    *alloc_ctx;
>       int                     desc_count;
>       int                     desc_nelts;
>       struct solo_p2m_desc    *desc_items;
> diff --git a/drivers/media/pci/tw68/tw68-core.c
> b/drivers/media/pci/tw68/tw68-core.c index 63f0b64..c135165 100644
> --- a/drivers/media/pci/tw68/tw68-core.c
> +++ b/drivers/media/pci/tw68/tw68-core.c
> @@ -304,13 +304,19 @@ static int tw68_initdev(struct pci_dev *pci_dev,
>       /* Then do any initialisation wanted before interrupts are on */
>       tw68_hw_init1(dev);
> 
> +     dev->alloc_ctx = vb2_dma_sg_init_ctx(&pci_dev->dev);
> +     if (IS_ERR(dev->alloc_ctx)) {
> +             err = PTR_ERR(dev->alloc_ctx);
> +             goto fail3;
> +     }
> +
>       /* get irq */
>       err = devm_request_irq(&pci_dev->dev, pci_dev->irq, tw68_irq,
>                         IRQF_SHARED, dev->name, dev);
>       if (err < 0) {
>               pr_err("%s: can't get IRQ %d\n",
>                      dev->name, pci_dev->irq);
> -             goto fail3;
> +             goto fail4;
>       }
> 
>       /*
> @@ -324,7 +330,7 @@ static int tw68_initdev(struct pci_dev *pci_dev,
>       if (err < 0) {
>               pr_err("%s: can't register video device\n",
>                      dev->name);
> -             goto fail4;
> +             goto fail5;
>       }
>       tw_setl(TW68_INTMASK, dev->pci_irqmask);
> 
> @@ -333,8 +339,10 @@ static int tw68_initdev(struct pci_dev *pci_dev,
> 
>       return 0;
> 
> -fail4:
> +fail5:
>       video_unregister_device(&dev->vdev);
> +fail4:
> +     vb2_dma_sg_cleanup_ctx(dev->alloc_ctx);
>  fail3:
>       iounmap(dev->lmmio);
>  fail2:
> @@ -358,6 +366,7 @@ static void tw68_finidev(struct pci_dev *pci_dev)
>       /* unregister */
>       video_unregister_device(&dev->vdev);
>       v4l2_ctrl_handler_free(&dev->hdl);
> +     vb2_dma_sg_cleanup_ctx(dev->alloc_ctx);
> 
>       /* release resources */
>       iounmap(dev->lmmio);
> diff --git a/drivers/media/pci/tw68/tw68-video.c
> b/drivers/media/pci/tw68/tw68-video.c index 5c94ac7..50dcce6 100644
> --- a/drivers/media/pci/tw68/tw68-video.c
> +++ b/drivers/media/pci/tw68/tw68-video.c
> @@ -384,6 +384,7 @@ static int tw68_queue_setup(struct vb2_queue *q, const
> struct v4l2_format *fmt, unsigned tot_bufs = q->num_buffers + *num_buffers;
> 
>       sizes[0] = (dev->fmt->depth * dev->width * dev->height) >> 3;
> +     alloc_ctxs[0] = dev->alloc_ctx;
>       /*
>        * We allow create_bufs, but only if the sizeimage is the same as the
>        * current sizeimage. The tw68_buffer_count calculation becomes quite
> diff --git a/drivers/media/pci/tw68/tw68.h b/drivers/media/pci/tw68/tw68.h
> index 2c8abe2..7a7501b 100644
> --- a/drivers/media/pci/tw68/tw68.h
> +++ b/drivers/media/pci/tw68/tw68.h
> @@ -181,6 +181,7 @@ struct tw68_dev {
>       unsigned                field;
>       struct vb2_queue        vidq;
>       struct list_head        active;
> +     void                    *alloc_ctx;
> 
>       /* various v4l controls */
>       const struct tw68_tvnorm *tvnorm;       /* video */
> diff --git a/drivers/media/platform/marvell-ccic/mcam-core.c
> b/drivers/media/platform/marvell-ccic/mcam-core.c index f0eeb6c..c3ff538
> 100644
> --- a/drivers/media/platform/marvell-ccic/mcam-core.c
> +++ b/drivers/media/platform/marvell-ccic/mcam-core.c
> @@ -1079,6 +1079,8 @@ static int mcam_vb_queue_setup(struct vb2_queue *vq,
>               *nbufs = minbufs;
>       if (cam->buffer_mode == B_DMA_contig)
>               alloc_ctxs[0] = cam->vb_alloc_ctx;
> +     else if (cam->buffer_mode == B_DMA_sg)
> +             alloc_ctxs[0] = cam->vb_alloc_ctx_sg;
>       return 0;
>  }
> 
> @@ -1286,10 +1288,12 @@ static int mcam_setup_vb2(struct mcam_camera *cam)
>               vq->ops = &mcam_vb2_ops;
>               vq->mem_ops = &vb2_dma_contig_memops;
>               vq->buf_struct_size = sizeof(struct mcam_vb_buffer);
> -             cam->vb_alloc_ctx = vb2_dma_contig_init_ctx(cam->dev);
>               vq->io_modes = VB2_MMAP | VB2_USERPTR;
>               cam->dma_setup = mcam_ctlr_dma_contig;
>               cam->frame_complete = mcam_dma_contig_done;
> +             cam->vb_alloc_ctx = vb2_dma_contig_init_ctx(cam->dev);
> +             if (IS_ERR(cam->vb_alloc_ctx))
> +                     return PTR_ERR(cam->vb_alloc_ctx);
>  #endif
>               break;
>       case B_DMA_sg:
> @@ -1300,6 +1304,9 @@ static int mcam_setup_vb2(struct mcam_camera *cam)
>               vq->io_modes = VB2_MMAP | VB2_USERPTR;
>               cam->dma_setup = mcam_ctlr_dma_sg;
>               cam->frame_complete = mcam_dma_sg_done;
> +             cam->vb_alloc_ctx_sg = vb2_dma_sg_init_ctx(cam->dev);
> +             if (IS_ERR(cam->vb_alloc_ctx_sg))
> +                     return PTR_ERR(cam->vb_alloc_ctx_sg);
>  #endif
>               break;
>       case B_vmalloc:
> @@ -1325,6 +1332,10 @@ static void mcam_cleanup_vb2(struct mcam_camera *cam)
> if (cam->buffer_mode == B_DMA_contig)
>               vb2_dma_contig_cleanup_ctx(cam->vb_alloc_ctx);
>  #endif
> +#ifdef MCAM_MODE_DMA_SG
> +     if (cam->buffer_mode == B_DMA_sg)
> +             vb2_dma_sg_cleanup_ctx(cam->vb_alloc_ctx_sg);
> +#endif
>  }
> 
> 
> diff --git a/drivers/media/platform/marvell-ccic/mcam-core.h
> b/drivers/media/platform/marvell-ccic/mcam-core.h index 60a8e1c..aa0c6ea
> 100644
> --- a/drivers/media/platform/marvell-ccic/mcam-core.h
> +++ b/drivers/media/platform/marvell-ccic/mcam-core.h
> @@ -176,6 +176,7 @@ struct mcam_camera {
>       /* DMA buffers - DMA modes */
>       struct mcam_vb_buffer *vb_bufs[MAX_DMA_BUFS];
>       struct vb2_alloc_ctx *vb_alloc_ctx;
> +     struct vb2_alloc_ctx *vb_alloc_ctx_sg;
> 
>       /* Mode-specific ops, set at open time */
>       void (*dma_setup)(struct mcam_camera *cam);
> diff --git a/drivers/media/v4l2-core/videobuf2-dma-sg.c
> b/drivers/media/v4l2-core/videobuf2-dma-sg.c index 2529b83..2bf13dc 100644
> --- a/drivers/media/v4l2-core/videobuf2-dma-sg.c
> +++ b/drivers/media/v4l2-core/videobuf2-dma-sg.c
> @@ -30,7 +30,12 @@ module_param(debug, int, 0644);
>                       printk(KERN_DEBUG "vb2-dma-sg: " fmt, ## arg);  \
>       } while (0)
> 
> +struct vb2_dma_sg_conf {
> +     struct device           *dev;
> +};
> +
>  struct vb2_dma_sg_buf {
> +     struct device                   *dev;
>       void                            *vaddr;
>       struct page                     **pages;
>       int                             offset;
> @@ -89,10 +94,13 @@ static int vb2_dma_sg_alloc_compacted(struct
> vb2_dma_sg_buf *buf, static void *vb2_dma_sg_alloc(void *alloc_ctx,
> unsigned long size, enum dma_data_direction dma_dir, gfp_t gfp_flags)
>  {
> +     struct vb2_dma_sg_conf *conf = alloc_ctx;
>       struct vb2_dma_sg_buf *buf;
>       int ret;
>       int num_pages;
> 
> +     if (WARN_ON(alloc_ctx == NULL))
> +             return NULL;
>       buf = kzalloc(sizeof *buf, GFP_KERNEL);
>       if (!buf)
>               return NULL;
> @@ -118,6 +126,8 @@ static void *vb2_dma_sg_alloc(void *alloc_ctx, unsigned
> long size, if (ret)
>               goto fail_table_alloc;
> 
> +     /* Prevent the device from being released while the buffer is used */
> +     buf->dev = get_device(conf->dev);
>       buf->handler.refcount = &buf->refcount;
>       buf->handler.put = vb2_dma_sg_put;
>       buf->handler.arg = buf;
> @@ -153,6 +163,7 @@ static void vb2_dma_sg_put(void *buf_priv)
>               while (--i >= 0)
>                       __free_page(buf->pages[i]);
>               kfree(buf->pages);
> +             put_device(buf->dev);
>               kfree(buf);
>       }
>  }
> @@ -356,6 +367,27 @@ const struct vb2_mem_ops vb2_dma_sg_memops = {
>  };
>  EXPORT_SYMBOL_GPL(vb2_dma_sg_memops);
> 
> +void *vb2_dma_sg_init_ctx(struct device *dev)
> +{
> +     struct vb2_dma_sg_conf *conf;
> +
> +     conf = kzalloc(sizeof(*conf), GFP_KERNEL);
> +     if (!conf)
> +             return ERR_PTR(-ENOMEM);
> +
> +     conf->dev = dev;
> +
> +     return conf;
> +}
> +EXPORT_SYMBOL_GPL(vb2_dma_sg_init_ctx);
> +
> +void vb2_dma_sg_cleanup_ctx(void *alloc_ctx)
> +{
> +     if (!IS_ERR_OR_NULL(alloc_ctx))
> +             kfree(alloc_ctx);
> +}
> +EXPORT_SYMBOL_GPL(vb2_dma_sg_cleanup_ctx);
> +
>  MODULE_DESCRIPTION("dma scatter/gather memory handling routines for
> videobuf2"); MODULE_AUTHOR("Andrzej Pietrasiewicz");
>  MODULE_LICENSE("GPL");
> diff --git a/include/media/videobuf2-dma-sg.h
> b/include/media/videobuf2-dma-sg.h index 7b89852..14ce306 100644
> --- a/include/media/videobuf2-dma-sg.h
> +++ b/include/media/videobuf2-dma-sg.h
> @@ -21,6 +21,9 @@ static inline struct sg_table *vb2_dma_sg_plane_desc(
>       return (struct sg_table *)vb2_plane_cookie(vb, plane_no);
>  }
> 
> +void *vb2_dma_sg_init_ctx(struct device *dev);
> +void vb2_dma_sg_cleanup_ctx(void *alloc_ctx);
> +
>  extern const struct vb2_mem_ops vb2_dma_sg_memops;
> 
>  #endif

-- 
Regards,

Laurent Pinchart

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