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drm/radeon: change vblank_time's calculation method to reduce computational error.

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Ported from Rex's amdgpu change.

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
This commit is contained in:
Alex Deucher 2016-10-12 15:28:55 -04:00
parent dc8184aa86
commit 02cfb5fccb
1 changed files with 8 additions and 7 deletions
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15
drivers/gpu/drm/radeon/r600_dpm.c
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@ -156,19 +156,20 @@ u32 r600_dpm_get_vblank_time(struct radeon_device *rdev)
struct drm_device *dev = rdev->ddev;
struct drm_crtc *crtc;
struct radeon_crtc *radeon_crtc;
u32 line_time_us, vblank_lines;
u32 vblank_in_pixels;
u32 vblank_time_us = 0xffffffff; /* if the displays are off, vblank time is max */
if (rdev->num_crtc && rdev->mode_info.mode_config_initialized) {
list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
radeon_crtc = to_radeon_crtc(crtc);
if (crtc->enabled && radeon_crtc->enabled && radeon_crtc->hw_mode.clock) {
line_time_us = (radeon_crtc->hw_mode.crtc_htotal * 1000) /
radeon_crtc->hw_mode.clock;
vblank_lines = radeon_crtc->hw_mode.crtc_vblank_end -
radeon_crtc->hw_mode.crtc_vdisplay +
(radeon_crtc->v_border * 2);
vblank_time_us = vblank_lines * line_time_us;
vblank_in_pixels =
radeon_crtc->hw_mode.crtc_htotal *
(radeon_crtc->hw_mode.crtc_vblank_end -
radeon_crtc->hw_mode.crtc_vdisplay +
(radeon_crtc->v_border * 2));
vblank_time_us = vblank_in_pixels * 1000 / radeon_crtc->hw_mode.clock;
break;
}
}