From: Imre Deak Date: Thu, 20 Nov 2014 14:05:55 +0000 (+0200) Subject: drm/i915: vlv: fix IRQ masking when uninstalling interrupts X-Git-Tag: v3.19-rc2~5^2~4^2~5 X-Git-Url: https://openfabrics.org/gitweb/?a=commitdiff_plain;h=c352d1ba1e1e2c8a96af660944a58e86b12ac4af;p=~emulex%2Finfiniband.git drm/i915: vlv: fix IRQ masking when uninstalling interrupts 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 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@vger.kernel.org (v3.15+) Signed-off-by: Imre Deak Reviewed-by: Ville Syrjälä Signed-off-by: Jani Nikula --- diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c index 981834b0f9b..8bab2ab228b 100644 --- a/drivers/gpu/drm/i915/i915_irq.c +++ b/drivers/gpu/drm/i915/i915_irq.c @@ -3609,7 +3609,7 @@ 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; } static void valleyview_irq_uninstall(struct drm_device *dev)