[PATCH v3 06/12] drm/amdgpu: create kernel doorbell pages

Shashank Sharma shashank.sharma at amd.com
Wed Jun 21 09:10:01 UTC 2023


Hey Christian,

On 21/06/2023 10:32, Christian König wrote:
> Am 20.06.23 um 19:16 schrieb Shashank Sharma:
>> This patch:
>> - creates a doorbell page for graphics driver usages.
>> - adds a few new varlables in adev->doorbell structure to
>>    keep track of kernel's doorbell-bo.
>> - removes the adev->doorbell.ptr variable, replaces it with
>>    kernel-doorbell-bo's cpu address.
>>
>> V2: - Create doorbell BO directly, no wrappe functions (Alex)
>>      - no additional doorbell structure (Alex, Christian)
>>      - Use doorbell_cpu_ptr, remove ioremap (Christian, Alex)
>>      - Allocate one extra page of doorbells for MES (Alex)
>>
>> Cc: Alex Deucher <alexander.deucher at amd.com>
>> Cc: Christian Koenig <christian.koenig at amd.com>
>> Signed-off-by: Shashank Sharma <shashank.sharma at amd.com>
>> ---
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell.h  |  8 ++-
>>   .../gpu/drm/amd/amdgpu/amdgpu_doorbell_mgr.c  | 56 ++++++++++++++-----
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_mes.h       |  3 +
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c       |  7 +++
>>   4 files changed, 60 insertions(+), 14 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell.h 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell.h
>> index 783e2b8b086c..002899edb9d7 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell.h
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell.h
>> @@ -31,10 +31,15 @@ struct amdgpu_doorbell {
>>       /* doorbell mmio */
>>       resource_size_t        base;
>>       resource_size_t        size;
>> -    u32 __iomem        *ptr;
>>         /* Number of doorbells reserved for amdgpu kernel driver */
>>       u32 num_kernel_doorbells;
>> +
>> +    /* Kernel doorbells */
>> +    struct amdgpu_bo *kernel_doorbells;
>> +
>> +    /* For CPU access of doorbells */
>> +    uint32_t *cpu_addr;
>>   };
>>     /* Reserved doorbells for amdgpu (including multimedia).
>> @@ -311,6 +316,7 @@ void amdgpu_mm_wdoorbell64(struct amdgpu_device 
>> *adev, u32 index, u64 v);
>>    */
>>   int amdgpu_doorbell_init(struct amdgpu_device *adev);
>>   void amdgpu_doorbell_fini(struct amdgpu_device *adev);
>> +int amdgpu_doorbell_create_kernel_doorbells(struct amdgpu_device 
>> *adev);
>>     #define RDOORBELL32(index) amdgpu_mm_rdoorbell(adev, (index))
>>   #define WDOORBELL32(index, v) amdgpu_mm_wdoorbell(adev, (index), (v))
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell_mgr.c 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell_mgr.c
>> index eb113e38f5e9..118f4bed32fd 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell_mgr.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell_mgr.c
>> @@ -39,7 +39,7 @@ u32 amdgpu_mm_rdoorbell(struct amdgpu_device *adev, 
>> u32 index)
>>           return 0;
>>         if (index < adev->doorbell.num_kernel_doorbells)
>> -        return readl(adev->doorbell.ptr + index);
>> +        return readl(adev->doorbell.cpu_addr + index);
>>         DRM_ERROR("reading beyond doorbell aperture: 0x%08x!\n", index);
>>       return 0;
>> @@ -61,7 +61,7 @@ void amdgpu_mm_wdoorbell(struct amdgpu_device 
>> *adev, u32 index, u32 v)
>>           return;
>>         if (index < adev->doorbell.num_kernel_doorbells)
>> -        writel(v, adev->doorbell.ptr + index);
>> +        writel(v, adev->doorbell.cpu_addr + index);
>>       else
>>           DRM_ERROR("writing beyond doorbell aperture: 0x%08x!\n", 
>> index);
>>   }
>> @@ -81,7 +81,7 @@ u64 amdgpu_mm_rdoorbell64(struct amdgpu_device 
>> *adev, u32 index)
>>           return 0;
>>         if (index < adev->doorbell.num_kernel_doorbells)
>> -        return atomic64_read((atomic64_t *)(adev->doorbell.ptr + 
>> index));
>> +        return atomic64_read((atomic64_t *)(adev->doorbell.cpu_addr 
>> + index));
>>         DRM_ERROR("reading beyond doorbell aperture: 0x%08x!\n", index);
>>       return 0;
>> @@ -103,11 +103,47 @@ void amdgpu_mm_wdoorbell64(struct amdgpu_device 
>> *adev, u32 index, u64 v)
>>           return;
>>         if (index < adev->doorbell.num_kernel_doorbells)
>> -        atomic64_set((atomic64_t *)(adev->doorbell.ptr + index), v);
>> +        atomic64_set((atomic64_t *)(adev->doorbell.cpu_addr + 
>> index), v);
>>       else
>>           DRM_ERROR("writing beyond doorbell aperture: 0x%08x!\n", 
>> index);
>>   }
>>   +/**
>> + * amdgpu_doorbell_create_kernel_doorbells - Create kernel doorbells 
>> for graphics
>> + *
>> + * @adev: amdgpu_device pointer
>> + *
>> + * Creates doorbells for graphics driver usages.
>> + * returns 0 on success, error otherwise.
>> + */
>> +int amdgpu_doorbell_create_kernel_doorbells(struct amdgpu_device *adev)
>> +{
>> +    int r;
>> +    int size;
>> +
>> +    /* Reserve first num_kernel_doorbells (page-aligned) for kernel 
>> ops */
>> +    size = ALIGN(adev->doorbell.num_kernel_doorbells * sizeof(u32), 
>> PAGE_SIZE);
>> +
>> +    /* Allocate an extra page for MES kernel usages (ring test) */
>> +    adev->mes.db_start_dw_offset = size / sizeof(u32);
>> +    size += PAGE_SIZE;
>
> This is initialized but not used, so I suspect it will temporary break 
> the MES test? Or is the MES just implicitly using the correct offset 
> somehow?

I am not sure if I understand this comment properly, can you please 
elaborate ?

If you are talking about 'size', its just used below while creating the 
doorbell BO.

If you mean adev->mes.db_start_dw_offset, its being used in 
amdgpu_mes_kernel_doorbell_get/free and amdgpu_mes_doorbell_init

So both of the variables are being used.

- Shashank

>
> Apart from that it looks good to me,
> Christian.
>
>> +
>> +    r = amdgpu_bo_create_kernel(adev,
>> +                    size,
>> +                    PAGE_SIZE,
>> +                    AMDGPU_GEM_DOMAIN_DOORBELL,
>> +                    &adev->doorbell.kernel_doorbells,
>> +                    NULL,
>> +                    (void **)&adev->doorbell.cpu_addr);
>> +    if (r) {
>> +        DRM_ERROR("Failed to allocate kernel doorbells, err=%d\n", r);
>> +        return r;
>> +    }
>> +
>> +    adev->doorbell.num_kernel_doorbells = size / sizeof(u32);
>> +    return 0;
>> +}
>> +
>>   /*
>>    * GPU doorbell aperture helpers function.
>>    */
>> @@ -127,7 +163,6 @@ int amdgpu_doorbell_init(struct amdgpu_device *adev)
>>           adev->doorbell.base = 0;
>>           adev->doorbell.size = 0;
>>           adev->doorbell.num_kernel_doorbells = 0;
>> -        adev->doorbell.ptr = NULL;
>>           return 0;
>>       }
>>   @@ -156,12 +191,6 @@ int amdgpu_doorbell_init(struct amdgpu_device 
>> *adev)
>>       if (adev->asic_type >= CHIP_VEGA10)
>>           adev->doorbell.num_kernel_doorbells += 0x400;
>>   -    adev->doorbell.ptr = ioremap(adev->doorbell.base,
>> -                     adev->doorbell.num_kernel_doorbells *
>> -                     sizeof(u32));
>> -    if (adev->doorbell.ptr == NULL)
>> -        return -ENOMEM;
>> -
>>       return 0;
>>   }
>>   @@ -174,6 +203,7 @@ int amdgpu_doorbell_init(struct amdgpu_device 
>> *adev)
>>    */
>>   void amdgpu_doorbell_fini(struct amdgpu_device *adev)
>>   {
>> -    iounmap(adev->doorbell.ptr);
>> -    adev->doorbell.ptr = NULL;
>> + amdgpu_bo_free_kernel(&adev->doorbell.kernel_doorbells,
>> +                  NULL,
>> +                  (void **)&adev->doorbell.cpu_addr);
>>   }
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_mes.h 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_mes.h
>> index 547ec35691fa..a403418d5eac 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_mes.h
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_mes.h
>> @@ -128,6 +128,9 @@ struct amdgpu_mes {
>>       int                             (*kiq_hw_init)(struct 
>> amdgpu_device *adev);
>>       int                             (*kiq_hw_fini)(struct 
>> amdgpu_device *adev);
>>   +    /* MES doorbells */
>> +    uint32_t            db_start_dw_offset;
>> +
>>       /* ip specific functions */
>>       const struct amdgpu_mes_funcs   *funcs;
>>   };
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
>> index 6d1587bbda52..c48e97646541 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
>> @@ -1854,6 +1854,13 @@ int amdgpu_ttm_init(struct amdgpu_device *adev)
>>           return r;
>>       }
>>   +    /* Create a boorbell page for kernel usages */
>> +    r = amdgpu_doorbell_create_kernel_doorbells(adev);
>> +    if (r) {
>> +        DRM_ERROR("Failed to initialize kernel doorbells.\n");
>> +        return r;
>> +    }
>> +
>>       /* Initialize preemptible memory pool */
>>       r = amdgpu_preempt_mgr_init(adev);
>>       if (r) {
>


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