On Thu, Nov 20, 2014 at 04:05:55PM +0200, Imre Deak wrote: > irq_mask should include all IRQ bits that we want to mask, but atm we > set it incorrectly to the inverse of this. If the mask is used > subsequently to enable/disable some IRQ bits, we may unintentionally > unmask unrelated IRQs. I can't see any way that this can lead to a real > problem in the current -nightly code, since the first place the mask > will be used next (after a suspend/resume cycle) is in > valleyview_irq_postinstall(), but the mask is reset there to its proper > value. > > This causes a problem in the upstream kernel though, where - due to another > issue - the mask is used in the above way to disable only the display IRQs. > This other issue is fixed by: > > commit 950eabaf5a87257040e0c207be09487954113f54 > Author: Imre Deak <imre.deak@xxxxxxxxx> > Date: Mon Sep 8 15:21:09 2014 +0300 > > drm/i915: vlv: fix display IRQ enable/disable > > Interestingly, even with the above two bugs, we shouldn't in theory have > any real problems (arguably a famous last sentence:). That's because > even if we unmask something unintentionally via the VLV_IMR/VLV_IER > register the master IRQ masking bit in VLV_MASTER_IER is still set and > should prevent all i915 interrupts. According to my testing on an ASUS > T100 with DSI output this isn't the case at least with the > MIPIA_INTERRUPT. Leaving this one unmasked in IMR/IER, while having > VLV_MASTER_IER set to 0 may lead to a lockup during system suspend as > shown in the bugzilla ticket below. This fix should get rid of the > problem reported there in upstream and older kernels. > > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=85920 > Cc: stable@xxxxxxxxxxxxxxx (v3.15+) > Signed-off-by: Imre Deak <imre.deak@xxxxxxxxx> > --- > drivers/gpu/drm/i915/i915_irq.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c > index 8d169e1..4601f53 100644 > --- a/drivers/gpu/drm/i915/i915_irq.c > +++ b/drivers/gpu/drm/i915/i915_irq.c > @@ -3597,7 +3597,7 @@ static void vlv_display_irq_uninstall(struct drm_i915_private *dev_priv) > > vlv_display_irq_reset(dev_priv); > > - dev_priv->irq_mask = 0; > + dev_priv->irq_mask = ~0; vlv seems to be the only platform which resets irq masks in the uninstall hook. That smells fishy - can't we just remove this completely? -Daniel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html