[PATCH] drm: Schedule the output_poll_work with 1s delay if we have delayed event
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 at vger.kernel.org # v4.9
> >> Signed-off-by: Peter Ujfalusi
> >> ---
> >> 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(_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
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
[PATCH] drm: Schedule the output_poll_work with 1s delay if we have delayed event
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 at vger.kernel.org # v4.9
>> Signed-off-by: Peter Ujfalusi
>> ---
>> 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(_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 at lists.freedesktop.org
>> https://lists.freedesktop.org/mailman/listinfo/dri-devel
>
--
Péter
[PATCH] drm: Schedule the output_poll_work with 1s delay if we have delayed event
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 at vger.kernel.org # v4.9
> Signed-off-by: Peter Ujfalusi
> ---
> 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(_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 at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
[PATCH] drm: Schedule the output_poll_work with 1s delay if we have delayed event
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 at vger.kernel.org # v4.9
Signed-off-by: Peter Ujfalusi
---
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(_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)
--
2.11.0
