[PATCH 5/8] drm/amd/pm: Treat zero vblank time as too short in si_dpm (v2)

[Timur Kristóf]

Some parts of the code base expect that MCLK switching is turned
off when the vblank time is set to zero.

According to pp_pm_compute_clocks the non-DC code has issues
with MCLK switching with refresh rates over 120 Hz.

Fixes: 841686df9f7d ("drm/amdgpu: add SI DPM support (v4)")
Signed-off-by: Timur Kristóf <timur.kristof at gmail.com>
---
 drivers/gpu/drm/amd/pm/legacy-dpm/si_dpm.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/pm/legacy-dpm/si_dpm.c b/drivers/gpu/drm/amd/pm/legacy-dpm/si_dpm.c
index db46fc0817a7..1e2aeea0b552 100644
--- a/drivers/gpu/drm/amd/pm/legacy-dpm/si_dpm.c
+++ b/drivers/gpu/drm/amd/pm/legacy-dpm/si_dpm.c
@@ -3082,8 +3082,8 @@ static bool si_dpm_vblank_too_short(void *handle)
 {
 	struct amdgpu_device *adev = (struct amdgpu_device *)handle;
 	u32 vblank_time = amdgpu_dpm_get_vblank_time(adev);
-	/* we never hit the non-gddr5 limit so disable it */
-	u32 switch_limit = adev->gmc.vram_type == AMDGPU_VRAM_TYPE_GDDR5 ? 450 : 0;
+	/* we never hit the non-gddr5 limit so disable it (but treat 0 as too short) */
+	u32 switch_limit = adev->gmc.vram_type == AMDGPU_VRAM_TYPE_GDDR5 ? 450 : 1;
 
 	if (vblank_time < switch_limit)
 		return true;
-- 
2.50.1