[RFC PATCH 4/7] drm/amdgpu: Add mmio_remap fields to amdgpu_device

[Deucher, Alexander]

[Public]

> -----Original Message-----
> From: SHANMUGAM, SRINIVASAN <SRINIVASAN.SHANMUGAM at amd.com>
> Sent: Wednesday, August 20, 2025 7:33 AM
> To: Koenig, Christian <Christian.Koenig at amd.com>; Deucher, Alexander
> <Alexander.Deucher at amd.com>
> Cc: amd-gfx at lists.freedesktop.org; SHANMUGAM, SRINIVASAN
> <SRINIVASAN.SHANMUGAM at amd.com>
> Subject: [RFC PATCH 4/7] drm/amdgpu: Add mmio_remap fields to amdgpu_device
>
> Add bookkeeping for the remap page to struct amdgpu_device:
>
> * mmio_remap_bo (singleton BO)
> * mmio_remap_base, mmio_remap_barsz (register BAR base/size)
> * mmio_remap_offset (BAR-relative offset of the remap page)
> * mmio_remap_size (PAGE_SIZE)

It's not PAGE_SIZE it's 4K.  If the PAGE_SIZE is >4K on the system, then we can't support this.

>
> Cc: Christian König <christian.koenig at amd.com>
> Cc: Alex Deucher <alexander.deucher at amd.com>
> Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam at amd.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu.h | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> index ddd472e56f69..6c477596617b 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> @@ -1038,6 +1038,13 @@ struct amdgpu_device {
>       amdgpu_block_wreg_t             audio_endpt_wreg;
>       struct amdgpu_doorbell          doorbell;
>
> +     /* ===== MMIO remap (HDP flush) bookkeeping ===== */
> +     struct amdgpu_bo                *mmio_remap_bo;   /* singleton BO */
> +     resource_size_t                  mmio_remap_base;  /* REG BAR bus base */
> +     resource_size_t                  mmio_remap_barsz; /* REG BAR size */
> +     resource_size_t                  mmio_remap_offset;/* BAR-relative offset of
> remap page */
> +     resource_size_t                  mmio_remap_size;  /* always PAGE_SIZE */

Always 4K.

Alex


> +
>       /* clock/pll info */
>       struct amdgpu_clock            clock;
>
> --
> 2.34.1