From 96b4026878d9dac71bd4c3d6e05c7fbb16a3e0aa Mon Sep 17 00:00:00 2001 From: Paulo Zanoni Date: Fri, 6 Dec 2013 20:29:01 -0200 Subject: [PATCH] drm/i915: change CRTC assertion on LCPLL disable Currently, PC8 is enabled at modeset_global_resources, which is called after intel_modeset_update_state. Due to this, there's a small race condition on the case where we start enabling PC8, then do a modeset while PC8 is still being enabled. The racing condition triggers a WARN because intel_modeset_update_state will mark the CRTC as enabled, then the thread that's still enabling PC8 might look at the data structure and think that PC8 is being enabled while a pipe is enabled. Despite the WARN, this is not really a bug since we'll wait for the PC8-enabling thread to finish when we call modeset_global_resources. The spec says the CRTC cannot be enabled when we disable LCPLL, so we had a check for crtc->base.enabled. If we change to crtc->active we will still prevent disabling LCPLL while the CRTC is enabled, and we will also prevent the WARN above. This is a replacement for the previous patch named "drm/i915: get/put PC8 when we get/put a CRTC" Testcase: igt/pm_pc8/modeset-lpsp-stress-no-wait Signed-off-by: Paulo Zanoni (cherry picked from commit 798183c54799fbe1e5a5bfabb3a8c0505ffd2149 from -next due to Dave's report.) Reported-by: Dave Jones Cc: stable@vger.kernel.org Signed-off-by: Daniel Vetter --- drivers/gpu/drm/i915/intel_display.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c index 8b8bde7dce53..4049a65a9f8c 100644 --- a/drivers/gpu/drm/i915/intel_display.c +++ b/drivers/gpu/drm/i915/intel_display.c @@ -6303,7 +6303,7 @@ static void assert_can_disable_lcpll(struct drm_i915_private *dev_priv) uint32_t val; list_for_each_entry(crtc, &dev->mode_config.crtc_list, base.head) - WARN(crtc->base.enabled, "CRTC for pipe %c enabled\n", + WARN(crtc->active, "CRTC for pipe %c enabled\n", pipe_name(crtc->pipe)); WARN(I915_READ(HSW_PWR_WELL_DRIVER), "Power well on\n"); -- GitLab