Re: [PATCH] drm/i915: Fix irq enable tracking in driver load

[Jani Nikula <jani.nikula@linux.intel.com>]

On Thu, 04 Sep 2014, Daniel Vetter <daniel@ffwll.ch> wrote:
> On Thu, Sep 04, 2014 at 04:42:36PM +0300, Jani Nikula wrote:
>> On Thu, 04 Sep 2014, Daniel Vetter <daniel@ffwll.ch> wrote:
>> > On Thu, Sep 04, 2014 at 02:12:10PM +0300, Jani Nikula wrote:
>> >> On Wed, 27 Aug 2014, Daniel Vetter <daniel.vetter@ffwll.ch> wrote:
>> >> > A bunch of warnings fire on some ->irq_postinstall hooks since those
>> >> > can enable interrupts (e.g. rps interrupts). And then our ordering
>> >> > self-checks fire and complain.
>> >> >
>> >> > To fix that set the tracking boolen before enabling the irqs witho
>> >> > drm_irq_install. Quoting the discussion with Jesse why that's safe:
>> >> 
>> >> Yi Sun's testing result needs to be addressed one way or another before
>> >> merging this:
>> >> 
>> >> http://mid.gmane.org/D9F66AA509623343B6A9A3D4502D5A52112B0676@SHSMSX101.ccr.corp.intel.com
>> >
>> > Shrug it off as an unstable test result. Both mine and Jesse's patch
>> > really only change the logic we use to WARN about interrupt state. We
>> > don't use pm._irqs_disabled for anything else at all.
>> 
>> Okay, so this is a PITA to review, but at least
>> ironlake_enable_display_irq will behave differently during
>> drm_irq_install because of this patch.
>
> Oops, I've somehow completely missed the early return in there. That means
> we actually break the ironlake rps setup done in postinstall without any
> of these patches. I've mixed this up with the pipestat check I've done
> where I just WARN, but don't bail out.
>
> tbh not sure why we bail out, at worst we'll get a few unclaimed register
> warnings.
>
> The only other place is if we get an interrupt right away, but that means
> the preinstall hook has a bug somewhere. So the only place where behaviour
> chances is still only ironlake, so still no explanation why hsw/bdw
> suddenly start to fall over all together.

Pushed to drm-intel-fixes. Thanks for the patch, testing and review.

BR,
Jani.



> -Daniel
> -- 
> Daniel Vetter
> Software Engineer, Intel Corporation
> +41 (0) 79 365 57 48 - http://blog.ffwll.ch

-- 
Jani Nikula, Intel Open Source Technology Center