On 2023-03-30 10:34, Shashank Sharma wrote:
>
> On 30/03/2023 16:15, Luben Tuikov wrote:
>> On 2023-03-30 10:04, Shashank Sharma wrote:
>>> On 30/03/2023 15:42, Luben Tuikov wrote:
>>>> On 2023-03-29 11:47, Shashank Sharma wrote:
>>>>> From: Shashank Sharma <contactshashanksharma@xxxxxxxxx>
>>>>>
>>>>> This patch adds helper functions to create and free doorbell
>>>>> pages for kernel objects.
>>>>>
>>>>> Cc: Alex Deucher <alexander.deucher@xxxxxxx>
>>>>> Cc: Christian Koenig <christian.koenig@xxxxxxx>
>>>>> Signed-off-by: Shashank Sharma <shashank.sharma@xxxxxxx>
>>>>> ---
>>>>> drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell.h | 41 ++++++++++++++++
>>>>> .../gpu/drm/amd/amdgpu/amdgpu_doorbell_mgr.c | 49 +++++++++++++++++++
>>>>> 2 files changed, 90 insertions(+)
>>>>>
>>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell.h
>>>>> index f9c3b77bf65d..6581b78fe438 100644
>>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell.h
>>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell.h
>>>>> @@ -27,6 +27,24 @@
>>>>> /*
>>>>> * GPU doorbell structures, functions & helpers
>>>>> */
>>>>> +
>>>>> +/* Structure to hold doorbell pages from PCI doorbell BAR */
>>>>> +struct amdgpu_doorbell_obj {
>>>> In the comment you say "Structure to hold ...";
>>>> it is a C structure, but then in the name of a function we see "obj".
>>>> (Object is something which is defined like in memory, i.e. it exists, not
>>>> something which is only declared.)
>>>> This is just a declaration of a structure, not an object per se.
>>>> I'd call it "struct amdgpu_doorbell_struct" or just "struct amdgpu_doorbell".
>>> It is similar to struct amdgpu buffer object (struct amdgpu_bo), and
>>> many more existing structure.
>> The amdpgu_bo is very different than a structure describing a doorbell.
>> The doorbell description isn't really "an object". I understand
>> the enthusiasm, but it is really not "an object". It's just a doorbell
>> description. :-)
>
> amdgpu_bo is page of ttm_memory with additional information,
>
> amdgpu_doorbell_obj is a page of ttm_doorbells with additional information
>
> (it is not just one doorbell description)
>
> I don't see a problem here.
There is no problem, it just descriptively may be confusing to future
maintainers and readers.
If amdgpu_doobell_obj stores a page/pages maybe "amdgpu_doorbell_bo"
would be more descriptive.
I'm merely trying to find the closest descriptive name, since
this not being C++, using "obj" is confusing.
Regards,
Luben
>
> - Shashank
>
>>
>> Regards,
>> Luben
>>
>>> - Shashank
>>>
>>>> Then in the definition, you can call it an object/objects, if you'd like,
>>>> like "struct amdgpu_doorbell *doorb_object[];" then you can say
>>>> "db = doorb_object[i]";
>>>>
>>>> Regards,
>>>> Luben
>>>>
>>>>> + struct amdgpu_bo *bo;
>>>>> + uint64_t gpu_addr;
>>>>> + uint32_t *cpu_addr;
>>>>> + uint32_t size;
>>>>> +
>>>>> + /* First index in this object */
>>>>> + uint32_t start;
>>>>> +
>>>>> + /* Last index in this object */
>>>>> + uint32_t end;
>>>>> +
>>>>> + /* bitmap for dynamic doorbell allocation from this object */
>>>>> + unsigned long *doorbell_bitmap;
>>>>> +};
>>>>> +
>>>>> struct amdgpu_doorbell {
>>>>> /* doorbell mmio */
>>>>> resource_size_t base;
>>>>> @@ -328,6 +346,29 @@ int amdgpu_device_doorbell_init(struct amdgpu_device *adev);
>>>>> */
>>>>> void amdgpu_device_doorbell_fini(struct amdgpu_device *adev);
>>>>>
>>>>> +/**
>>>>> + * amdgpu_doorbell_free_page - Free a doorbell page
>>>>> + *
>>>>> + * @adev: amdgpu_device pointer
>>>>> + *
>>>>> + * @db_age: previously allocated doobell page details
>>>>> + *
>>>>> + */
>>>>> +void amdgpu_doorbell_free_page(struct amdgpu_device *adev,
>>>>> + struct amdgpu_doorbell_obj *db_obj);
>>>>> +
>>>>> +/**
>>>>> + * amdgpu_doorbell_alloc_page - create a page from doorbell pool
>>>>> + *
>>>>> + * @adev: amdgpu_device pointer
>>>>> + *
>>>>> + * @db_age: doobell page structure to fill details with
>>>>> + *
>>>>> + * returns 0 on success, else error number
>>>>> + */
>>>>> +int amdgpu_doorbell_alloc_page(struct amdgpu_device *adev,
>>>>> + struct amdgpu_doorbell_obj *db_obj);
>>>>> +
>>>>> #define RDOORBELL32(index) amdgpu_mm_rdoorbell(adev, (index))
>>>>> #define WDOORBELL32(index, v) amdgpu_mm_wdoorbell(adev, (index), (v))
>>>>> #define RDOORBELL64(index) amdgpu_mm_rdoorbell64(adev, (index))
>>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell_mgr.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell_mgr.c
>>>>> index 1aea92363fd3..8be15b82b545 100644
>>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell_mgr.c
>>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell_mgr.c
>>>>> @@ -111,6 +111,55 @@ void amdgpu_mm_wdoorbell64(struct amdgpu_device *adev, u32 index, u64 v)
>>>>> }
>>>>> }
>>>>>
>>>>> +/**
>>>>> + * amdgpu_doorbell_free_page - Free a doorbell page
>>>>> + *
>>>>> + * @adev: amdgpu_device pointer
>>>>> + *
>>>>> + * @db_age: previously allocated doobell page details
>>>>> + *
>>>>> + */
>>>>> +void amdgpu_doorbell_free_page(struct amdgpu_device *adev,
>>>>> + struct amdgpu_doorbell_obj *db_obj)
>>>>> +{
>>>>> + amdgpu_bo_free_kernel(&db_obj->bo,
>>>>> + &db_obj->gpu_addr,
>>>>> + (void **)&db_obj->cpu_addr);
>>>>> +
>>>>> +}
>>>>> +
>>>>> +/**
>>>>> + * amdgpu_doorbell_alloc_page - create a page from doorbell pool
>>>>> + *
>>>>> + * @adev: amdgpu_device pointer
>>>>> + *
>>>>> + * @db_age: doobell page structure to fill details with
>>>>> + *
>>>>> + * returns 0 on success, else error number
>>>>> + */
>>>>> +int amdgpu_doorbell_alloc_page(struct amdgpu_device *adev,
>>>>> + struct amdgpu_doorbell_obj *db_obj)
>>>>> +{
>>>>> + int r;
>>>>> +
>>>>> + db_obj->size = ALIGN(db_obj->size, PAGE_SIZE);
>>>>> +
>>>>> + r = amdgpu_bo_create_kernel(adev,
>>>>> + db_obj->size,
>>>>> + PAGE_SIZE,
>>>>> + AMDGPU_GEM_DOMAIN_DOORBELL,
>>>>> + &db_obj->bo,
>>>>> + &db_obj->gpu_addr,
>>>>> + (void **)&db_obj->cpu_addr);
>>>>> +
>>>>> + if (r) {
>>>>> + DRM_ERROR("Failed to create doorbell BO, err=%d\n", r);
>>>>> + return r;
>>>>> + }
>>>>> +
>>>>> + return 0;
>>>>> +}
>>>>> +
>>>>> /*
>>>>> * GPU doorbell aperture helpers function.
>>>>> */
