Now that we update the watermark values atomically, we still need to fix the case of how we update watermarks when we haven't added or removed pipes. When we haven't added or removed any pipes, we don't need to worry about the ddb allocation changing. As such there's no order of flushing pipes we have to guarantee; e.g. each pipe can be flushed at the earliest given oppurtunity. This means all we have to do is: - Calculate the new wm values - Update each plane's settings and wm values - Arm the plane's registers to update at the next vblank Right now the watermark code takes an additional few steps: - Rewrite the ddb allocations - Arm all of the planes for another update at the start of the next vblank - *Potentially underrun later if we update the wm registers before the start of the next vblank* This patch prevents us from marking pipes as dirty unless the number of pipes, and with that the ddb allocation, has actually changed. This results in us skipping the additional steps, preventing the hardware from using any intermediate values during each wm update. This also fixes cursors causing monitors to flicker on Skylake. Finally. Signed-off-by: Lyude Paul <cpaul@xxxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> Cc: Daniel Vetter <daniel.vetter@xxxxxxxxx> Cc: Radhakrishna Sripada <radhakrishna.sripada@xxxxxxxxx> Cc: Hans de Goede <hdegoede@xxxxxxxxxx> Cc: Matt Roper <matthew.d.roper@xxxxxxxxx> --- drivers/gpu/drm/i915/intel_pm.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c index 3a7709c..92158e3 100644 --- a/drivers/gpu/drm/i915/intel_pm.c +++ b/drivers/gpu/drm/i915/intel_pm.c @@ -4086,12 +4086,18 @@ skl_compute_wm(struct drm_atomic_state *state) if (ret) return ret; - if (changed) - results->dirty_pipes |= drm_crtc_mask(crtc); + /* + * We don't need to do any additional setup for the pipes if we + * haven't changed the number of active crtcs + */ + if (intel_state->active_pipe_changes) { + if (changed) + results->dirty_pipes |= drm_crtc_mask(crtc); - if ((results->dirty_pipes & drm_crtc_mask(crtc)) == 0) - /* This pipe's WM's did not change */ - continue; + if ((results->dirty_pipes & drm_crtc_mask(crtc)) == 0) + /* This pipe's WM's did not change */ + continue; + } intel_cstate->update_wm_pre = true; skl_compute_wm_results(crtc->dev, pipe_wm, results, intel_crtc); -- 2.7.4 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html