Re: [PATCH 02/10] drm/ttm: flip over the range manager to self allocated nodes

["Thomas Hellström (Intel)" <thomas_os@shipmail.org>]

On 6/2/21 8:41 PM, Christian König wrote:
> Am 02.06.21 um 17:28 schrieb Thomas Hellström (Intel):
>> Hi!
>>
>> On 6/2/21 4:17 PM, Christian König wrote:
>>> Am 02.06.21 um 16:13 schrieb Thomas Hellström (Intel):
>>>>
>>>> On 6/2/21 3:07 PM, Christian König wrote:
>>>>>
>>>>>
>>>>> Am 02.06.21 um 14:33 schrieb Thomas Hellström (Intel):
>>>>>>
>>>>>> On 6/2/21 2:11 PM, Christian König wrote:
>>>>>>> Am 02.06.21 um 13:44 schrieb Thomas Hellström (Intel):
>>>>>>>>
>>>>>>>> On 6/2/21 12:09 PM, Christian König wrote:
>>>>>>>>> Start with the range manager to make the resource object the base
>>>>>>>>> class for the allocated nodes.
>>>>>>>>>
>>>>>>>>> While at it cleanup a lot of the code around that.
>>>>>>>>>
>>>>>>>>> Signed-off-by: Christian König <christian.koenig@amd.com>
>>>>>>>>> Reviewed-by: Matthew Auld <matthew.auld@intel.com>
>>>>>>>>> ---
>>>>>>>>>   drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c |  1 +
>>>>>>>>>   drivers/gpu/drm/drm_gem_vram_helper.c   |  2 +
>>>>>>>>>   drivers/gpu/drm/nouveau/nouveau_ttm.c   |  2 +
>>>>>>>>>   drivers/gpu/drm/qxl/qxl_ttm.c           |  1 +
>>>>>>>>>   drivers/gpu/drm/radeon/radeon_ttm.c     |  1 +
>>>>>>>>>   drivers/gpu/drm/ttm/ttm_range_manager.c | 56 
>>>>>>>>> ++++++++++++++++++-------
>>>>>>>>>   drivers/gpu/drm/ttm/ttm_resource.c      | 26 ++++++++----
>>>>>>>>>   include/drm/ttm/ttm_bo_driver.h         | 26 ------------
>>>>>>>>>   include/drm/ttm/ttm_range_manager.h     | 43 
>>>>>>>>> +++++++++++++++++++
>>>>>>>>>   include/drm/ttm/ttm_resource.h          |  3 ++
>>>>>>>>>   10 files changed, 111 insertions(+), 50 deletions(-)
>>>>>>>>>   create mode 100644 include/drm/ttm/ttm_range_manager.h
>>>>>>>>>
>>>>>>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c 
>>>>>>>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
>>>>>>>>> index 69db89261650..df1f185faae9 100644
>>>>>>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
>>>>>>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
>>>>>>>>> @@ -45,6 +45,7 @@
>>>>>>>>>   #include <drm/ttm/ttm_bo_api.h>
>>>>>>>>>   #include <drm/ttm/ttm_bo_driver.h>
>>>>>>>>>   #include <drm/ttm/ttm_placement.h>
>>>>>>>>> +#include <drm/ttm/ttm_range_manager.h>
>>>>>>>>>     #include <drm/amdgpu_drm.h>
>>>>>>>>>   diff --git a/drivers/gpu/drm/drm_gem_vram_helper.c 
>>>>>>>>> b/drivers/gpu/drm/drm_gem_vram_helper.c
>>>>>>>>> index 83e7258c7f90..17a4c5d47b6a 100644
>>>>>>>>> --- a/drivers/gpu/drm/drm_gem_vram_helper.c
>>>>>>>>> +++ b/drivers/gpu/drm/drm_gem_vram_helper.c
>>>>>>>>> @@ -17,6 +17,8 @@
>>>>>>>>>   #include <drm/drm_prime.h>
>>>>>>>>>   #include <drm/drm_simple_kms_helper.h>
>>>>>>>>>   +#include <drm/ttm/ttm_range_manager.h>
>>>>>>>>> +
>>>>>>>>>   static const struct drm_gem_object_funcs 
>>>>>>>>> drm_gem_vram_object_funcs;
>>>>>>>>>     /**
>>>>>>>>> diff --git a/drivers/gpu/drm/nouveau/nouveau_ttm.c 
>>>>>>>>> b/drivers/gpu/drm/nouveau/nouveau_ttm.c
>>>>>>>>> index 65430912ff72..b08b8efeefba 100644
>>>>>>>>> --- a/drivers/gpu/drm/nouveau/nouveau_ttm.c
>>>>>>>>> +++ b/drivers/gpu/drm/nouveau/nouveau_ttm.c
>>>>>>>>> @@ -26,6 +26,8 @@
>>>>>>>>>   #include <linux/limits.h>
>>>>>>>>>   #include <linux/swiotlb.h>
>>>>>>>>>   +#include <drm/ttm/ttm_range_manager.h>
>>>>>>>>> +
>>>>>>>>>   #include "nouveau_drv.h"
>>>>>>>>>   #include "nouveau_gem.h"
>>>>>>>>>   #include "nouveau_mem.h"
>>>>>>>>> diff --git a/drivers/gpu/drm/qxl/qxl_ttm.c 
>>>>>>>>> b/drivers/gpu/drm/qxl/qxl_ttm.c
>>>>>>>>> index 8aa87b8edb9c..19fd39d9a00c 100644
>>>>>>>>> --- a/drivers/gpu/drm/qxl/qxl_ttm.c
>>>>>>>>> +++ b/drivers/gpu/drm/qxl/qxl_ttm.c
>>>>>>>>> @@ -32,6 +32,7 @@
>>>>>>>>>   #include <drm/ttm/ttm_bo_api.h>
>>>>>>>>>   #include <drm/ttm/ttm_bo_driver.h>
>>>>>>>>>   #include <drm/ttm/ttm_placement.h>
>>>>>>>>> +#include <drm/ttm/ttm_range_manager.h>
>>>>>>>>>     #include "qxl_drv.h"
>>>>>>>>>   #include "qxl_object.h"
>>>>>>>>> diff --git a/drivers/gpu/drm/radeon/radeon_ttm.c 
>>>>>>>>> b/drivers/gpu/drm/radeon/radeon_ttm.c
>>>>>>>>> index cdffa9b65108..ad2a5a791bba 100644
>>>>>>>>> --- a/drivers/gpu/drm/radeon/radeon_ttm.c
>>>>>>>>> +++ b/drivers/gpu/drm/radeon/radeon_ttm.c
>>>>>>>>> @@ -45,6 +45,7 @@
>>>>>>>>>   #include <drm/ttm/ttm_bo_api.h>
>>>>>>>>>   #include <drm/ttm/ttm_bo_driver.h>
>>>>>>>>>   #include <drm/ttm/ttm_placement.h>
>>>>>>>>> +#include <drm/ttm/ttm_range_manager.h>
>>>>>>>>>     #include "radeon_reg.h"
>>>>>>>>>   #include "radeon.h"
>>>>>>>>> diff --git a/drivers/gpu/drm/ttm/ttm_range_manager.c 
>>>>>>>>> b/drivers/gpu/drm/ttm/ttm_range_manager.c
>>>>>>>>> index b9d5da6e6a81..ce5d07ca384c 100644
>>>>>>>>> --- a/drivers/gpu/drm/ttm/ttm_range_manager.c
>>>>>>>>> +++ b/drivers/gpu/drm/ttm/ttm_range_manager.c
>>>>>>>>> @@ -29,12 +29,13 @@
>>>>>>>>>    * Authors: Thomas Hellstrom <thellstrom-at-vmware-dot-com>
>>>>>>>>>    */
>>>>>>>>>   -#include <drm/ttm/ttm_bo_driver.h>
>>>>>>>>> +#include <drm/ttm/ttm_device.h>
>>>>>>>>>   #include <drm/ttm/ttm_placement.h>
>>>>>>>>> +#include <drm/ttm/ttm_range_manager.h>
>>>>>>>>> +#include <drm/ttm/ttm_bo_api.h>
>>>>>>>>>   #include <drm/drm_mm.h>
>>>>>>>>>   #include <linux/slab.h>
>>>>>>>>>   #include <linux/spinlock.h>
>>>>>>>>> -#include <linux/module.h>
>>>>>>>>>     /*
>>>>>>>>>    * Currently we use a spinlock for the lock, but a mutex 
>>>>>>>>> *may* be
>>>>>>>>> @@ -60,8 +61,8 @@ static int ttm_range_man_alloc(struct 
>>>>>>>>> ttm_resource_manager *man,
>>>>>>>>>                      struct ttm_resource *mem)
>>>>>>>>>   {
>>>>>>>>>       struct ttm_range_manager *rman = to_range_manager(man);
>>>>>>>>> +    struct ttm_range_mgr_node *node;
>>>>>>>>>       struct drm_mm *mm = &rman->mm;
>>>>>>>>> -    struct drm_mm_node *node;
>>>>>>>>>       enum drm_mm_insert_mode mode;
>>>>>>>>>       unsigned long lpfn;
>>>>>>>>>       int ret;
>>>>>>>>> @@ -70,7 +71,7 @@ static int ttm_range_man_alloc(struct 
>>>>>>>>> ttm_resource_manager *man,
>>>>>>>>>       if (!lpfn)
>>>>>>>>>           lpfn = man->size;
>>>>>>>>>   -    node = kzalloc(sizeof(*node), GFP_KERNEL);
>>>>>>>>> +    node = kzalloc(struct_size(node, mm_nodes, 1), GFP_KERNEL);
>>>>>>>>
>>>>>>>> I'm still a bit confused  about the situation where a driver 
>>>>>>>> wants to attach private data to a struct ttm_resource without 
>>>>>>>> having to re-implement its own range manager?
>>>>>>>>
>>>>>>>> Could be cached sg-tables, list of GPU bindings etc. Wouldn't 
>>>>>>>> work with the above unless we have a void *driver_private 
>>>>>>>> member on the struct ttm_resource. Is that the plan going 
>>>>>>>> forward here? Or that the driver actually does the 
>>>>>>>> re-implementation?
>>>>>>>
>>>>>>> I don't really understand your concern here. The basic idea is 
>>>>>>> that drivers use ttm_resource as a base class for their own 
>>>>>>> implementation.
>>>>>>>
>>>>>>> See for example how nouveau does that:
>>>>>>>
>>>>>>> struct nouveau_mem {
>>>>>>>         struct ttm_resource base;
>>>>>>>         struct nouveau_cli *cli;
>>>>>>>         u8 kind;
>>>>>>>         u8 comp;
>>>>>>>         struct nvif_mem mem;
>>>>>>>         struct nvif_vma vma[2];
>>>>>>> };
>>>>>>>
>>>>>>> The range manager is helping driver specific resource managers 
>>>>>>> which want to implement something drm_mm_nodes based. E.g. 
>>>>>>> amdgpu_gtt_mgr and amdgpu_vram_mgr, but it can also be used 
>>>>>>> stand alone.
>>>>>>>
>>>>>>> The ttm_range_mgr_node can then be used as base class for this 
>>>>>>> functionality. I already want to move some more code from 
>>>>>>> amdgpu_vram_mgr.c into the range manager, but that is just minor 
>>>>>>> cleanup work.
>>>>>>>
>>>>>> Sure but if you embed a ttm_range_mgr_node in your struct 
>>>>>> i915_resource, and wanted to use the ttm range manager for it, it 
>>>>>> would allocate a struct ttm_range_mgr_node rather than a struct 
>>>>>> i915_resource? Or am I missing something?
>>>>>
>>>>> Yes, that's the general idea I'm targeting for. I'm just not fully 
>>>>> there yet.
>>>>
>>>> Hmm, I don't fully understand the reply, I described a buggy 
>>>> scenario and you replied that's what we're targeting for?
>>>
>>> Ok, I don't seem to understand what you mean here. What is buggy on 
>>> that?
>>
>> The buggy thing I'm trying to describe is a scenario where I want to 
>> have a struct i915_ttm_resource which embeds a struct 
>> ttm_range_mgr_node, but there is no way I can tell the generic ttm 
>> range manager to allocate a struct i915_ttm_resource instead of a 
>> struct ttm_range_mgr_node.
>>
>> So what I want to be able to do: I have
>>
>> struct i915_ttm_resource {
>>         struct i915_gpu_bindings gpu_bindings;
>>         struct ttm_range_mgr_node range_node;
>> };
>>
>> Now I want to be able to share common code as much as possible and 
>> use the generic ttm_range_manager here. How would I go about doing 
>> that with the proposed changes?
>
> Ah, yes that is the part I haven't moved over yet. In other words that 
> is not possible yet.

OK, that "yet" sounds good. So this will be possible moving forward? 
(Basically it's the overall design that's not completely clear to me 
yet, not really the code itself)

Thanks,

Thomas