On Tue, Jul 17, 2018 at 09:33:52AM +0200, Lukas Wunner wrote:
On Thu, Jul 12, 2018 at 01:02:53PM -0400, Lyude Paul wrote:
--- a/drivers/gpu/drm/nouveau/dispnv50/disp.c +++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c @@ -1878,7 +1878,7 @@ nv50_disp_atomic_commit(struct drm_device *dev, nv50_disp_atomic_commit_tail(state);
drm_for_each_crtc(crtc, dev) {
if (crtc->state->enable) {
if (crtc->state->active) { if (!drm->have_disp_power_ref) { drm->have_disp_power_ref = true; return 0;Somewhat tangential comment on this older patch, since you continue to dig around in the runtime PM area:
Whenever a crtc is activated or deactivated in nouveau, we iterate over all crtcs and acquire a runtime PM if a crtc is active and previously there was no active one, or we drop a ref if none is active and previously there was an active one.
For a while now I've been thinking that it would be more straightforward to acquire a ref whenever a crtc is activated and drop one when a crtc is deactivated, i.e. hold one ref for every active crtc. That way the have_disp_power_ref variable as well as the iteration logic could be removed, leading to a simplification. Just a suggestion anyway.
The current code looks somewhat busted anyway. First problem is that it's accessing crtc->state without the appropriate locks held (unless something always pulls in all crtcs to every commit?). Second issue is that the rpm_put() is called without waiting for nonblocking commits to have finished so it looks like you can currentlly remove the power before the hardware has been properly shut down.