[v3 2/7] drm/amd/amdgpu: Implement SDMA soft reset directly for sdma v5

[Alex Deucher]

On Wed, Apr 2, 2025 at 5:23 AM Jesse.zhang at amd.com <jesse.zhang at amd.com> wrote:
>
> This patch introduces a new function `amdgpu_sdma_soft_reset` to handle SDMA soft resets directly,
> rather than relying on the DPM interface.
>
> 1. **New `amdgpu_sdma_soft_reset` Function**:
>    - Implements a soft reset for SDMA engines by directly writing to the hardware registers.
>    - Handles SDMA versions 4.x and 5.x separately:
>      - For SDMA 4.x, the existing `amdgpu_dpm_reset_sdma` function is used for backward compatibility.
>      - For SDMA 5.x, the driver directly manipulates the `GRBM_SOFT_RESET` register to reset the specified SDMA instance.
>
> 2. **Integration into `amdgpu_sdma_reset_engine`**:
>    - The `amdgpu_sdma_soft_reset` function is called during the SDMA reset process, replacing the previous call to `amdgpu_dpm_reset_sdma`.
>
> Suggested-by: Alex Deucher <alexander.deucher at amd.com>
> Signed-off-by: Jesse Zhang <jesse.zhang at amd.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_sdma.c | 46 +++++++++++++++++++++++-
>  1 file changed, 45 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_sdma.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_sdma.c
> index b51fe644940f..26d7c0aca9a8 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_sdma.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_sdma.c
> @@ -26,6 +26,8 @@
>  #include "amdgpu_sdma.h"
>  #include "amdgpu_ras.h"
>  #include "amdgpu_reset.h"
> +#include "gc/gc_10_1_0_offset.h"
> +#include "gc/gc_10_3_0_sh_mask.h"
>
>  #define AMDGPU_CSA_SDMA_SIZE 64
>  /* SDMA CSA reside in the 3rd page of CSA */
> @@ -553,6 +555,48 @@ void amdgpu_sdma_register_on_reset_callbacks(struct amdgpu_device *adev, struct
>         list_add_tail(&funcs->list, &adev->sdma.reset_callback_list);
>  }
>
> +static int amdgpu_sdma_soft_reset(struct amdgpu_device *adev, u32 instance_id)
> +{
> +       u32 soft_reset;
> +       int r = 0;
> +
> +       switch (amdgpu_ip_version(adev, SDMA0_HWIP, 0)) {
> +       case IP_VERSION(4, 4, 2):
> +       case IP_VERSION(4, 4, 4):
> +       case IP_VERSION(4, 4, 5):
> +               /* For SDMA 4.x, use the existing DPM interface for backward compatibility */
> +               r = amdgpu_dpm_reset_sdma(adev, 1 << instance_id);
> +               break;
> +       case IP_VERSION(5, 0, 0):
> +       case IP_VERSION(5, 0, 1):
> +       case IP_VERSION(5, 0, 2):
> +       case IP_VERSION(5, 0, 5):
> +       case IP_VERSION(5, 2, 0):
> +       case IP_VERSION(5, 2, 2):
> +       case IP_VERSION(5, 2, 4):
> +       case IP_VERSION(5, 2, 5):
> +       case IP_VERSION(5, 2, 6):
> +       case IP_VERSION(5, 2, 3):
> +       case IP_VERSION(5, 2, 1):
> +       case IP_VERSION(5, 2, 7):
> +               /* For SDMA 5.x, directly manipulate the GRBM_SOFT_RESET register */
> +               soft_reset = RREG32_SOC15(GC, 0, mmGRBM_SOFT_RESET);
> +               soft_reset |= 1 << GRBM_SOFT_RESET__SOFT_RESET_SDMA0__SHIFT << instance_id;
> +               /* Issue the soft reset */
> +               WREG32_SOC15(GC, 0, mmGRBM_SOFT_RESET, soft_reset);
> +
> +               udelay(50);
> +               /* Clear the soft reset bit */
> +               soft_reset &= ~(1 << GRBM_SOFT_RESET__SOFT_RESET_SDMA0__SHIFT << instance_id);
> +               WREG32_SOC15(GC, 0, mmGRBM_SOFT_RESET, soft_reset);

I would move this into a helper function in sdma_v5_0.c and just call
that from here rather than including IP specific programming in this
file.  E.g.,

sdma_v5_0_soft_reset(adev, instance_id);

Alex

> +               break;
> +       default:
> +               break;
> +       }
> +
> +       return r;
> +}
> +
>  /**
>   * amdgpu_sdma_reset_engine - Reset a specific SDMA engine
>   * @adev: Pointer to the AMDGPU device
> @@ -587,7 +631,7 @@ int amdgpu_sdma_reset_engine(struct amdgpu_device *adev, uint32_t instance_id)
>                 gfx_ring->funcs->stop_queue(gfx_ring);
>
>         /* Perform the SDMA reset for the specified instance */
> -       ret = amdgpu_dpm_reset_sdma(adev, 1 << instance_id);
> +       ret = amdgpu_sdma_soft_reset(adev, instance_id);
>         if (ret) {
>                 dev_err(adev->dev, "Failed to reset SDMA instance %u\n", instance_id);
>                 goto exit;
> --
> 2.25.1
>