[PATCH] drm/amdgpu: Add delay after enable RLC ucode

[Kuehling, Felix]

On 2018-11-22 12:03 p.m., Liu, Shaoyun wrote:
> Driver shouldn't try to access any GFX registers until RLC is idle.
> During the test, it took 12 seconds for RLC to clear the BUSY bit
> in RLC_GPM_STAT register which is un-acceptable for driver.
> As per RLC engineer, it would take RLC Ucode less than 10,000 GFXCLK
> cycles to finish its critical section. In a lowest 300M enginer clock
> setting(default from vbios), 50 us delay is enough.
>
> Change-Id: If074fbeeecad3f63cf5f5ab232472d0fe46082a6
> Signed-off-by: shaoyunl <shaoyun.liu at amd.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c b/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
> index e409fbf..2e3ee42 100644
> --- a/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
> +++ b/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
> @@ -2326,6 +2326,7 @@ static void gfx_v9_0_rlc_start(struct amdgpu_device *adev)
>  #endif
>  
>  	WREG32_FIELD15(GC, 0, RLC_CNTL, RLC_ENABLE_F32, 1);
> +	udelay(50);
>  
>  	/* carrizo do enable cp interrupt after cp inited */
>  	if (!(adev->flags & AMD_IS_APU))

                gfx_v9_0_enable_gui_idle_interrupt(adev, true);

        udelay(50);

There is already another udelay(50) here. Is that one still needed?

Regards,
  Felix