From: Tarun <tarun.vyas@xxxxxxxxx> The PIPEDSL freezes on PSR entry and if PSR hasn't fully exited, then the pipe_update_start call schedules itself out to check back later. On ChromeOS-4.4 kernel, which is fairly up-to-date w.r.t drm/i915 but lags w.r.t core kernel code, hot plugging an external display triggers tons of "potential atomic update errors" in the dmesg, on *pipe A*. A closer analysis reveals that we try to read the scanline 3 times and eventually timeout, b/c PSR hasn't exited fully leading to a PIPEDSL stuck @ 1599. This issue is not seen on upstream kernels, b/c for *some* reason we loop inside intel_pipe_update start for ~2+ msec which in this case is more than enough to exit PSR fully, hence an *unstuck* PIPEDSL counter, hence no error. On the other hand, the ChromeOS kernel spends ~1.1 msec looping inside intel_pipe_update_start and hence errors out b/c the source is still in PSR. Regardless, we should wait for PSR exit (if PSR is supported and active on the current pipe) before reading the PIPEDSL, b/c if we haven't fully exited PSR, then checking for vblank evasion isn't actually applicable. This scenario applies to a configuration with an additional pipe, as of now. --- drivers/gpu/drm/i915/intel_sprite.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_sprite.c b/drivers/gpu/drm/i915/intel_sprite.c index aa1dfaa692b9..135b41568503 100644 --- a/drivers/gpu/drm/i915/intel_sprite.c +++ b/drivers/gpu/drm/i915/intel_sprite.c @@ -107,14 +107,17 @@ void intel_pipe_update_start(const struct intel_crtc_state *new_crtc_state) VBLANK_EVASION_TIME_US); max = vblank_start - 1; - local_irq_disable(); - if (min <= 0 || max <= 0) return; if (WARN_ON(drm_crtc_vblank_get(&crtc->base))) return; + if(new_crtc_state->has_psr && dev_priv->psr.active) + intel_wait_for_register(dev_priv, EDP_PSR_STATUS, EDP_PSR_STATUS_STATE_MASK, EDP_PSR_STATUS_STATE_IDLE, 5); + + local_irq_disable(); + crtc->debug.min_vbl = min; crtc->debug.max_vbl = max; trace_i915_pipe_update_start(crtc); -- 2.13.5 _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
