[PATCH 09/16] drm/amdgpu: create kernel doorbell page

[Luben Tuikov]

On 2023-03-29 11:47, Shashank Sharma wrote:
> From: Shashank Sharma <contactshashanksharma at gmail.com>
> 
> This patch:
> - creates a doorbell page for graphics driver usages.
> - removes the adev->doorbell.ptr variable, replaces it with
>   kernel-doorbell-bo's cpu address.
> 
> 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  | 16 ++++++-
>  .../gpu/drm/amd/amdgpu/amdgpu_doorbell_mgr.c  | 44 +++++++++++++++----
>  drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c       |  7 +++
>  3 files changed, 57 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell.h
> index 6581b78fe438..10a9bb10e974 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell.h
> @@ -49,10 +49,13 @@ struct amdgpu_doorbell {
>  	/* doorbell mmio */
>  	resource_size_t		base;
>  	resource_size_t		size;
> -	u32 __iomem		*ptr;
> +	u32	__iomem		*ptr;
>  
>  	/* Number of doorbells reserved for amdgpu kernel driver */
>  	u32 num_kernel_doorbells;
> +
> +	/* For kernel doorbell pages */
> +	struct amdgpu_doorbell_obj kernel_doorbells;
>  };

Here's an example where it could be confusing what the difference is
between "struct amdgpu_doorbell" and "struct amdgpu_doobell_obj".
As the comment to the struct doorbell_obj declarations says
in patch 7,

> +/* Structure to hold doorbell pages from PCI doorbell BAR */
> +struct amdgpu_doorbell_obj {

Perhaps we should call it "struct amdgpu_doorbell_bo", since
it does contain amdgpu_bo's, which are doorbell's bos.

Regards,
Luben

>  
>  /* Reserved doorbells for amdgpu (including multimedia).
> @@ -369,6 +372,17 @@ void amdgpu_doorbell_free_page(struct amdgpu_device *adev,
>  int amdgpu_doorbell_alloc_page(struct amdgpu_device *adev,
>  				struct amdgpu_doorbell_obj *db_obj);
>  
> +/**
> + * amdgpu_doorbell_create_kernel_doorbells - Create kernel doorbells for graphics
> + *
> + * @adev: amdgpu_device pointer
> + *
> + * Creates doorbells for graphics driver
> + *
> + * returns 0 on success, error otherwise.
> + */
> +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))
>  #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 8be15b82b545..b46fe8b1378d 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell_mgr.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell_mgr.c
> @@ -160,6 +160,38 @@ int amdgpu_doorbell_alloc_page(struct amdgpu_device *adev,
>  	return 0;
>  }
>  
> +/**
> + * amdgpu_doorbell_create_kernel_doorbells - Create kernel doorbells for graphics
> + *
> + * @adev: amdgpu_device pointer
> + *
> + * Creates doorbells for graphics driver
> + *
> + * returns 0 on success, error otherwise.
> + */
> +int amdgpu_doorbell_create_kernel_doorbells(struct amdgpu_device *adev)
> +{
> +	int r;
> +	struct amdgpu_doorbell_obj *kernel_doorbells = &adev->doorbell.kernel_doorbells;
> +
> +	kernel_doorbells->doorbell_bitmap = bitmap_zalloc(adev->doorbell.num_kernel_doorbells,
> +							  GFP_KERNEL);
> +	if (!kernel_doorbells->doorbell_bitmap) {
> +		DRM_ERROR("Failed to create kernel doorbell bitmap\n");
> +		return -ENOMEM;
> +	}
> +
> +	kernel_doorbells->size = adev->doorbell.num_kernel_doorbells * sizeof(u32);
> +	r = amdgpu_doorbell_alloc_page(adev, kernel_doorbells);
> +	if (r) {
> +		bitmap_free(kernel_doorbells->doorbell_bitmap);
> +		DRM_ERROR("Failed to allocate kernel doorbells, err=%d\n", r);
> +		return r;
> +	}
> +
> +	return 0;
> +}
> +
>  /*
>   * GPU doorbell aperture helpers function.
>   */
> @@ -179,7 +211,6 @@ int amdgpu_device_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;
>  	}
>  
> @@ -208,12 +239,7 @@ int amdgpu_device_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;
> -
> +	adev->doorbell.ptr = ioremap(adev->doorbell.base, adev->doorbell.size);
>  	return 0;
>  }
>  
> @@ -226,6 +252,6 @@ int amdgpu_device_doorbell_init(struct amdgpu_device *adev)
>   */
>  void amdgpu_device_doorbell_fini(struct amdgpu_device *adev)
>  {
> -	iounmap(adev->doorbell.ptr);
> -	adev->doorbell.ptr = NULL;
> +	bitmap_free(adev->doorbell.kernel_doorbells.doorbell_bitmap);
> +	amdgpu_doorbell_free_page(adev, &adev->doorbell.kernel_doorbells);
>  }
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> index 203d77a20507..75c6852845c4 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> @@ -1866,6 +1866,13 @@ 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) {