FW: [PATCH v2 2/2] drm/amdgpu: Move to gtt before cpu accesses dma buf.
Deucher, Alexander
Alexander.Deucher at amd.com
Wed Dec 13 19:49:29 UTC 2017
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> on behalf of Samuel Li <samuel.li at amd.com>
Sent: Wednesday, December 13, 2017 2:17:49 PM
To: Koenig, Christian; 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
>>>>>> Cc: Li, Samuel <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
>>>>>>
>
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