| Message ID | 20170104120053.31882-1-peter.ujfalusi@ti.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, Jan 04, 2017 at 02:00:53PM +0200, Peter Ujfalusi wrote: > Instead of scheduling the work to handle the initial delayed event, use 1s > delay. > > When the delayed event is handled w/o delay - in a similar matter when the > poll had been initialized before drm_helper_probe_single_connector_modes() > is called - it triggers a race in Optimus setups. > > Fixes: 339fd36238dd ("drm: drm_probe_helper: Fix output_poll_work scheduling") > Cc: stable@vger.kernel.org # v4.9 > Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com> > --- > Hi, > > related bug report: https://bugs.freedesktop.org/show_bug.cgi?id=98690 > > Regards, > Peter > > drivers/gpu/drm/drm_probe_helper.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c > index 98ed110e28ed..f30c14b0a72f 100644 > --- a/drivers/gpu/drm/drm_probe_helper.c > +++ b/drivers/gpu/drm/drm_probe_helper.c > @@ -146,8 +146,9 @@ void drm_kms_helper_poll_enable_locked(struct drm_device *dev) > drm_connector_list_iter_put(&conn_iter); > > if (dev->mode_config.delayed_event) { > + /* Use short (1s) delay to handle the initial delayed event */ > poll = true; > - delay = 0; > + delay = HZ; This smells a bit like duct-tape papering over some other race. Lack of locking or something else. Most likely some drivers enable polling a bit too early in their load sequence. And if we can't figure this out, then we need some really big FIXME: here that this papers over driver races. -Daniel > } > > if (poll) > -- > 2.11.0 > > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel
On 01/05/2017 10:43 AM, Daniel Vetter wrote: > On Wed, Jan 04, 2017 at 02:00:53PM +0200, Peter Ujfalusi wrote: >> Instead of scheduling the work to handle the initial delayed event, use 1s >> delay. >> >> When the delayed event is handled w/o delay - in a similar matter when the >> poll had been initialized before drm_helper_probe_single_connector_modes() >> is called - it triggers a race in Optimus setups. >> >> Fixes: 339fd36238dd ("drm: drm_probe_helper: Fix output_poll_work scheduling") >> Cc: stable@vger.kernel.org # v4.9 >> Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com> >> --- >> Hi, >> >> related bug report: https://bugs.freedesktop.org/show_bug.cgi?id=98690 >> >> Regards, >> Peter >> >> drivers/gpu/drm/drm_probe_helper.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c >> index 98ed110e28ed..f30c14b0a72f 100644 >> --- a/drivers/gpu/drm/drm_probe_helper.c >> +++ b/drivers/gpu/drm/drm_probe_helper.c >> @@ -146,8 +146,9 @@ void drm_kms_helper_poll_enable_locked(struct drm_device *dev) >> drm_connector_list_iter_put(&conn_iter); >> >> if (dev->mode_config.delayed_event) { >> + /* Use short (1s) delay to handle the initial delayed event */ >> poll = true; >> - delay = 0; >> + delay = HZ; > > This smells a bit like duct-tape papering over some other race. Yes, I agree. We could revert 339fd36238dd also to put back the duct-tape. > Lack of > locking or something else. Most likely some drivers enable polling a bit > too early in their load sequence. All is pointing to Optimus. Intel and nouveau alone works, but we have failure on Optimus laptops. I have tried to narrow it down with another patch attached to the bugzilla: https://bugs.freedesktop.org/attachment.cgi?id=128742 I expected it to fix the problem. But it did not. So I'm puzzled. >And if we can't figure this out, then we > need some really big FIXME: here that this papers over driver races. Yeah, now we know that there is something wrong in some driver(s). We can hide it with delaying the poll_work. It would be great if nouveau/optimus guys would be able to take a look at this. > -Daniel > >> } >> >> if (poll) >> -- >> 2.11.0 >> >> _______________________________________________ >> dri-devel mailing list >> dri-devel@lists.freedesktop.org >> https://lists.freedesktop.org/mailman/listinfo/dri-devel >
On Thu, Jan 05, 2017 at 12:40:29PM +0200, Peter Ujfalusi wrote: > On 01/05/2017 10:43 AM, Daniel Vetter wrote: > > On Wed, Jan 04, 2017 at 02:00:53PM +0200, Peter Ujfalusi wrote: > >> Instead of scheduling the work to handle the initial delayed event, use 1s > >> delay. > >> > >> When the delayed event is handled w/o delay - in a similar matter when the > >> poll had been initialized before drm_helper_probe_single_connector_modes() > >> is called - it triggers a race in Optimus setups. > >> > >> Fixes: 339fd36238dd ("drm: drm_probe_helper: Fix output_poll_work scheduling") > >> Cc: stable@vger.kernel.org # v4.9 > >> Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com> > >> --- > >> Hi, > >> > >> related bug report: https://bugs.freedesktop.org/show_bug.cgi?id=98690 > >> > >> Regards, > >> Peter > >> > >> drivers/gpu/drm/drm_probe_helper.c | 3 ++- > >> 1 file changed, 2 insertions(+), 1 deletion(-) > >> > >> diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c > >> index 98ed110e28ed..f30c14b0a72f 100644 > >> --- a/drivers/gpu/drm/drm_probe_helper.c > >> +++ b/drivers/gpu/drm/drm_probe_helper.c > >> @@ -146,8 +146,9 @@ void drm_kms_helper_poll_enable_locked(struct drm_device *dev) > >> drm_connector_list_iter_put(&conn_iter); > >> > >> if (dev->mode_config.delayed_event) { > >> + /* Use short (1s) delay to handle the initial delayed event */ > >> poll = true; > >> - delay = 0; > >> + delay = HZ; > > > > This smells a bit like duct-tape papering over some other race. > > Yes, I agree. We could revert 339fd36238dd also to put back the duct-tape. Since the revert and this patch are the same kind of duct-tape (massive delay) I prefer something like this patch ... > > > Lack of > > locking or something else. Most likely some drivers enable polling a bit > > too early in their load sequence. > > All is pointing to Optimus. Intel and nouveau alone works, but we have > failure on Optimus laptops. > I have tried to narrow it down with another patch attached to the > bugzilla: https://bugs.freedesktop.org/attachment.cgi?id=128742 > > I expected it to fix the problem. But it did not. So I'm puzzled. > > >And if we can't figure this out, then we > > need some really big FIXME: here that this papers over driver races. > > Yeah, now we know that there is something wrong in some driver(s). We > can hide it with delaying the poll_work. It would be great if > nouveau/optimus guys would be able to take a look at this. ... but with all the above information (optimus only, what blows up) condensed into both the commit message and a big WARNING comment in the code. Then I think this is reasonable to merge (but still a decent wtf), since it addresses a rather serious regression. -Daniel
diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c index 98ed110e28ed..f30c14b0a72f 100644 --- a/drivers/gpu/drm/drm_probe_helper.c +++ b/drivers/gpu/drm/drm_probe_helper.c @@ -146,8 +146,9 @@ void drm_kms_helper_poll_enable_locked(struct drm_device *dev) drm_connector_list_iter_put(&conn_iter); if (dev->mode_config.delayed_event) { + /* Use short (1s) delay to handle the initial delayed event */ poll = true; - delay = 0; + delay = HZ; } if (poll)
Instead of scheduling the work to handle the initial delayed event, use 1s delay. When the delayed event is handled w/o delay - in a similar matter when the poll had been initialized before drm_helper_probe_single_connector_modes() is called - it triggers a race in Optimus setups. Fixes: 339fd36238dd ("drm: drm_probe_helper: Fix output_poll_work scheduling") Cc: stable@vger.kernel.org # v4.9 Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com> --- Hi, related bug report: https://bugs.freedesktop.org/show_bug.cgi?id=98690 Regards, Peter drivers/gpu/drm/drm_probe_helper.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)