FW: [PATCH v2 2/2] drm/amdgpu: Move to gtt before cpu accesses dma buf.

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Please CC Michel as well, he originally commented that we should try to 
solve this in the DDX instead.

And BTW: Why don't we just do the migration during the mmap call?

Christian.

Am 13.12.2017 um 22:28 schrieb Li, Samuel:
>
> Will do after some basic testing.
>
> Sam
>
> *From:*Deucher, Alexander
> *Sent:* Wednesday, December 13, 2017 2:49 PM
> *To:* Li, Samuel <Samuel.Li at amd.com>; Koenig, Christian 
> <Christian.Koenig at amd.com>; amd-gfx at lists.freedesktop.org
> *Subject:* Re: FW: [PATCH v2 2/2] drm/amdgpu: Move to gtt before cpu 
> accesses dma buf.
>
> Please send the drm prime patch to dri-devel if you didn't already.
>
> Alex
>
> ------------------------------------------------------------------------
>
> *From:*amd-gfx <amd-gfx-bounces at lists.freedesktop.org 
> <mailto:amd-gfx-bounces at lists.freedesktop.org>> on behalf of Samuel Li 
> <samuel.li at amd.com <mailto:samuel.li at amd.com>>
> *Sent:* Wednesday, December 13, 2017 2:17:49 PM
> *To:* Koenig, Christian; amd-gfx at lists.freedesktop.org 
> <mailto:amd-gfx at lists.freedesktop.org>
> *Subject:* Re: FW: [PATCH v2 2/2] drm/amdgpu: Move to gtt before cpu 
> accesses dma buf.
>
> For the record.
>
>
> On 2017-12-13 01:26 PM, Christian König wrote:
> > Actually we try to avoid that drivers define their own dma_buf_ops 
> in DRM.
> >
> > That's why you have all those callbacks in drm_driver which just 
> mirror the dma_buf interface but unpack the GEM object from the 
> dma-buf object.
> >
> > There are quite a number of exceptions, but those drivers then 
> implement everything on their own because the DRM marshaling doesn't 
> make sense for them.
> >
> > Christian.
> >
> > Am 13.12.2017 um 19:01 schrieb Samuel Li:
> >> That is an approach. The cost is to add a new call back, which is 
> not necessary though, since driver can always actually define their 
> own dma_buf_ops.
> >> The intention here is to allow a driver reuse 
> drm_gem_prime_dmabuf_ops{}. If you would like to go this far, maybe a 
> more straight forward way is to export those ops, e.g. 
> drm_gem_map_attach, so that a driver can use them in its own definitions.
> >>
> >> Sam
> >>
> >>
> >>
> >> On 2017-12-13 05:23 AM, Christian König wrote:
> >>> Something like the attached patch. Not even compile tested.
> >>>
> >>> Christian.
> >>>
> >>> Am 12.12.2017 um 20:13 schrieb Samuel Li:
> >>>> Not sure if I understand your comments correctly. Currently 
> amdgpu prime reuses drm_gem_prime_dmabuf_ops{}, and it is defined as 
> static which is reasonable. I do not see an easier way to introduce 
> amdgpu_gem_begin_cpu_access().
> >>>>
> >>>> Sam
> >>>>
> >>>> On 2017-12-12 01:30 PM, Christian König wrote:
> >>>>>> +    while (amdgpu_dmabuf_ops.begin_cpu_access != 
> amdgpu_gem_begin_cpu_access)
> >>>>> I would rather just add the four liner code to drm to forward 
> the begin_cpu_access callback into a drm_driver callback instead of 
> all this.
> >>>>>
> >>>>> But apart from that it looks good to me.
> >>>>>
> >>>>> Christian.
> >>>>>
> >>>>> Am 12.12.2017 um 19:14 schrieb Li, Samuel:
> >>>>>> A gentle ping on this one, Christian, can you take a look at this?
> >>>>>>
> >>>>>> Sam
> >>>>>>
> >>>>>> -----Original Message-----
> >>>>>> From: Li, Samuel
> >>>>>> Sent: Friday, December 08, 2017 5:22 PM
> >>>>>> To: amd-gfx at lists.freedesktop.org 
> <mailto:amd-gfx at lists.freedesktop.org>
> >>>>>> Cc: Li, Samuel <Samuel.Li at amd.com <mailto:Samuel.Li at amd.com>>
> >>>>>> Subject: [PATCH v2 2/2] drm/amdgpu: Move to gtt before cpu 
> accesses dma buf.
> >>>>>>
> >>>>>> To improve cpu read performance. This is implemented for APUs 
> currently.
> >>>>>>
> >>>>>> v2: Adapt to change 
> https://lists.freedesktop.org/archives/amd-gfx/2017-October/015174.html
> >>>>>>
> >>>>>> Change-Id: I7a583e23a9ee706e0edd2a46f4e4186a609368e3
> >>>>>> ---
> >>>>>> drivers/gpu/drm/amd/amdgpu/amdgpu.h       |  2 ++
> >>>>>> drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c   |  2 +-
> >>>>>> drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c | 58 
> +++++++++++++++++++++++++++++++
> >>>>>>     3 files changed, 61 insertions(+), 1 deletion(-)
> >>>>>>
> >>>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h 
> b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> >>>>>> index f8657c3..193db70 100644
> >>>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> >>>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> >>>>>> @@ -417,6 +417,8 @@ amdgpu_gem_prime_import_sg_table(struct 
> drm_device *dev,  struct dma_buf *amdgpu_gem_prime_export(struct 
> drm_device *dev,
> >>>>>> struct drm_gem_object *gobj,
> >>>>>>                         int flags);
> >>>>>> +struct drm_gem_object *amdgpu_gem_prime_import(struct 
> drm_device *dev,
> >>>>>> + struct dma_buf *dma_buf);
> >>>>>>     int amdgpu_gem_prime_pin(struct drm_gem_object *obj); void 
> amdgpu_gem_prime_unpin(struct drm_gem_object *obj);  struct 
> reservation_object *amdgpu_gem_prime_res_obj(struct drm_gem_object *); 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c 
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> >>>>>> index 31383e0..df30b08 100644
> >>>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> >>>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> >>>>>> @@ -868,7 +868,7 @@ static struct drm_driver kms_driver = {
> >>>>>>         .prime_handle_to_fd = drm_gem_prime_handle_to_fd,
> >>>>>>         .prime_fd_to_handle = drm_gem_prime_fd_to_handle,
> >>>>>>         .gem_prime_export = amdgpu_gem_prime_export,
> >>>>>> -    .gem_prime_import = drm_gem_prime_import,
> >>>>>> +    .gem_prime_import = amdgpu_gem_prime_import,
> >>>>>>         .gem_prime_pin = amdgpu_gem_prime_pin,
> >>>>>>         .gem_prime_unpin = amdgpu_gem_prime_unpin,
> >>>>>>         .gem_prime_res_obj = amdgpu_gem_prime_res_obj, diff 
> --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c 
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c
> >>>>>> index ae9c106..de6f599 100644
> >>>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c
> >>>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c
> >>>>>> @@ -26,6 +26,7 @@
> >>>>>>     #include <drm/drmP.h>
> >>>>>>       #include "amdgpu.h"
> >>>>>> +#include "amdgpu_display.h"
> >>>>>>     #include <drm/amdgpu_drm.h>
> >>>>>>     #include <linux/dma-buf.h>
> >>>>>>     @@ -164,6 +165,33 @@ struct reservation_object 
> *amdgpu_gem_prime_res_obj(struct drm_gem_object *obj)
> >>>>>>         return bo->tbo.resv;
> >>>>>>     }
> >>>>>>     +static int amdgpu_gem_begin_cpu_access(struct dma_buf 
> *dma_buf, enum
> >>>>>> +dma_data_direction direction) {
> >>>>>> +    struct amdgpu_bo *bo = gem_to_amdgpu_bo(dma_buf->priv);
> >>>>>> +    struct amdgpu_device *adev = amdgpu_ttm_adev(bo->tbo.bdev);
> >>>>>> +    struct ttm_operation_ctx ctx = { true, false };
> >>>>>> +    u32 domain = amdgpu_framebuffer_domains(adev);
> >>>>>> +    long ret = 0;
> >>>>>> +    bool reads = (direction == DMA_BIDIRECTIONAL || direction ==
> >>>>>> +DMA_FROM_DEVICE);
> >>>>>> +
> >>>>>> +    if (!reads || !(domain | AMDGPU_GEM_DOMAIN_GTT) || 
> bo->pin_count)
> >>>>>> +        return 0;
> >>>>>> +
> >>>>>> +    /* move to gtt */
> >>>>>> +    ret = amdgpu_bo_reserve(bo, false);
> >>>>>> +    if (unlikely(ret != 0))
> >>>>>> +        return ret;
> >>>>>> +
> >>>>>> + amdgpu_ttm_placement_from_domain(bo, AMDGPU_GEM_DOMAIN_GTT);
> >>>>>> +    ret = ttm_bo_validate(&bo->tbo, &bo->placement, &ctx);
> >>>>>> +
> >>>>>> +    amdgpu_bo_unreserve(bo);
> >>>>>> +    return ret;
> >>>>>> +}
> >>>>>> +
> >>>>>> +static struct dma_buf_ops amdgpu_dmabuf_ops; static atomic_t 
> aops_lock;
> >>>>>> +
> >>>>>>     struct dma_buf *amdgpu_gem_prime_export(struct drm_device *dev,
> >>>>>> struct drm_gem_object *gobj,
> >>>>>>                         int flags)
> >>>>>> @@ -178,5 +206,35 @@ struct dma_buf 
> *amdgpu_gem_prime_export(struct drm_device *dev,
> >>>>>>         buf = drm_gem_prime_export(dev, gobj, flags);
> >>>>>>         if (!IS_ERR(buf))
> >>>>>> buf->file->f_mapping = dev->anon_inode->i_mapping;
> >>>>>> +
> >>>>>> +    while (amdgpu_dmabuf_ops.begin_cpu_access != 
> amdgpu_gem_begin_cpu_access)
> >>>>>> +    {
> >>>>>> +        if (!atomic_cmpxchg(&aops_lock, 0, 1)) {
> >>>>>> + amdgpu_dmabuf_ops = *(buf->ops);
> >>>>>> + amdgpu_dmabuf_ops.begin_cpu_access = amdgpu_gem_begin_cpu_access;
> >>>>>> +        }
> >>>>>> +    }
> >>>>>> +    buf->ops = &amdgpu_dmabuf_ops;
> >>>>>> +
> >>>>>>         return buf;
> >>>>>>     }
> >>>>>> +
> >>>>>> +struct drm_gem_object *amdgpu_gem_prime_import(struct 
> drm_device *dev,
> >>>>>> + struct dma_buf *dma_buf)
> >>>>>> +{
> >>>>>> +    struct drm_gem_object *obj;
> >>>>>> +
> >>>>>> +    if (dma_buf->ops == &amdgpu_dmabuf_ops) {
> >>>>>> +        obj = dma_buf->priv;
> >>>>>> +        if (obj->dev == dev) {
> >>>>>> +            /*
> >>>>>> +             * Importing dmabuf exported from out own gem 
> increases
> >>>>>> +             * refcount on gem itself instead of f_count of 
> dmabuf.
> >>>>>> +             */
> >>>>>> + drm_gem_object_get(obj);
> >>>>>> +            return obj;
> >>>>>> +        }
> >>>>>> +    }
> >>>>>> +
> >>>>>> +    return drm_gem_prime_import(dev, dma_buf); }
> >>>>>> --
> >>>>>> 2.7.4
> >>>>>>
> >
>
>
>
> _______________________________________________
> amd-gfx mailing list
> amd-gfx at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/amd-gfx

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