On 21/06/17 10:44 AM, Mario Kleiner wrote:
> With instantaneous high precision vblank timestamping
> that updates at leading edge of vblank, a cooked hw
> vblank counter which increments at leading edge of
> vblank, and reliable page flip execution and completion
> at leading edge of vblank, we should meet the requirements
> for fast/immediate vblank irq disable/enable.
>
> Testing on Linux-4.12-rc5 + drm-next on a Radeon R9 380
> Tonga Pro (DCE 10) with timing measurement equipment
> indicates this works fine, so allow immediate vblank
> disable for power saving.
>
> For debugging in case of unexpected trouble, booting
> with kernel cmdline option drm.vblankoffdelay=0
> (or echo 0 > /sys/module/drm/parameters/vblankoffdelay)
> would keep vblank irqs permanently on to approximate old
> behavior.
>
> Signed-off-by: Mario Kleiner <mario.kleiner.de at gmail.com>
> Cc: Alex Deucher <alexander.deucher at amd.com>
> Cc: Michel Dänzer <michel.daenzer at amd.com>
> ---
> drivers/gpu/drm/amd/amdgpu/amdgpu_irq.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_irq.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_irq.c
> index 62da6c5..a28f8aa 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_irq.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_irq.c
> @@ -220,6 +220,10 @@ int amdgpu_irq_init(struct amdgpu_device *adev)
> int r = 0;
>
> spin_lock_init(&adev->irq.lock);
> +
> + /* Disable vblank irqs aggressively for power-saving */
> + adev->ddev->vblank_disable_immediate = true;
> +
> r = drm_vblank_init(adev->ddev, adev->mode_info.num_crtc);
> if (r) {
> return r;
>
Reviewed-by: Michel Dänzer <michel.daenzer at amd.com>
--
Earthling Michel Dänzer | http://www.amd.com
Libre software enthusiast | Mesa and X developer
