[PATCH] drm/amdgpu: Reconfigure ULV for gfx9 server SKUs

[Zhang, Hawking]

Reviewed-by: Hawking Zhang <Hawking.Zhang at amd.com>

Regards,
Hawking 

Sent from my iPhone

> On Jun 11, 2020, at 07:22, Joseph Greathouse <Joseph.Greathouse at amd.com> wrote:
> 
> SDMA ULV can benefit low-power modes, but can sometimes cause
> latency increases in small SDMA transfers. Server SKUs have a
> different trade-off space in this domain, so this configures
> the server SKUs' ULV hysteresis times differently than consumer
> SKUs'.
> 
> Signed-off-by: Joseph Greathouse <Joseph.Greathouse at amd.com>
> Change-Id: Ifc33aa857714c4c209b19a5d44e0a05c478db195
> ---
> drivers/gpu/drm/amd/amdgpu/sdma_v4_0.c | 32 ++++++++++++++++++++++++++
> 1 file changed, 32 insertions(+)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/sdma_v4_0.c b/drivers/gpu/drm/amd/amdgpu/sdma_v4_0.c
> index 2f1f47de9634..58382646d962 100644
> --- a/drivers/gpu/drm/amd/amdgpu/sdma_v4_0.c
> +++ b/drivers/gpu/drm/amd/amdgpu/sdma_v4_0.c
> @@ -505,6 +505,36 @@ static void sdma_v4_0_init_golden_registers(struct amdgpu_device *adev)
>    }
> }
> 
> +static void sdma_v4_0_setup_ulv(struct amdgpu_device *adev)
> +{
> +    int i;
> +
> +    /*
> +     * The only chips with SDMAv4 and ULV are VG10 and VG20.
> +     * Server SKUs take a different hysteresis setting from other SKUs.
> +     */
> +    switch (adev->asic_type) {
> +    case CHIP_VEGA10:
> +        if (adev->pdev->device == 0x6860)
> +            break;
> +        return;
> +    case CHIP_VEGA20:
> +        if (adev->pdev->device == 0x66a1)
> +            break;
> +        return;
> +    default:
> +        return;
> +    }
> +
> +    for (i = 0; i < adev->sdma.num_instances; i++) {
> +        uint32_t temp;
> +
> +        temp = RREG32_SDMA(i, mmSDMA0_ULV_CNTL);
> +        temp = REG_SET_FIELD(temp, SDMA0_ULV_CNTL, HYSTERESIS, 0x0);
> +        WREG32_SDMA(i, mmSDMA0_ULV_CNTL, temp);
> +    }
> +}
> +
> static int sdma_v4_0_init_inst_ctx(struct amdgpu_sdma_instance *sdma_inst)
> {
>    int err = 0;
> @@ -1813,6 +1843,8 @@ static int sdma_v4_0_late_init(void *handle)
>        .cb = sdma_v4_0_process_ras_data_cb,
>    };
> 
> +    sdma_v4_0_setup_ulv(adev);
> +
>    if (adev->sdma.funcs && adev->sdma.funcs->reset_ras_error_count)
>        adev->sdma.funcs->reset_ras_error_count(adev);
> 
> -- 
> 2.20.1
> 
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