On Mon, Jun 11, 2018 at 11:02:56PM +0300, Ville Syrjala wrote:
From: Ville Syrjälä ville.syrjala@linux.intel.com
Just like with PIPESTAT, the edge triggered IIR on i965/g4x also causes problems for hotplug interrupts. To make sure we don't get the IIR port interrupt bit stuck low with the ISR bit high we must force an edge in ISR. We do that by clearing PORT_HOTPLUG_EN temporaryly when we ack PORT_HOTPLUG_STAT.
Cc: stable@vger.kernel.org Signed-off-by: Ville Syrjälä ville.syrjala@linux.intel.com
drivers/gpu/drm/i915/i915_irq.c | 31 ++++++++++++++++++++++++++++--- 1 file changed, 28 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c index 364e1c85315e..59250ecbd0d9 100644 --- a/drivers/gpu/drm/i915/i915_irq.c +++ b/drivers/gpu/drm/i915/i915_irq.c @@ -1998,10 +1998,35 @@ static void valleyview_pipestat_irq_handler(struct drm_i915_private *dev_priv, static u32 i9xx_hpd_irq_ack(struct drm_i915_private *dev_priv) {
- u32 hotplug_status = I915_READ(PORT_HOTPLUG_STAT);
- u32 hotplug_status, hotplug_en;
- if (hotplug_status)
I915_WRITE(PORT_HOTPLUG_STAT, hotplug_status);
- hotplug_status = I915_READ(PORT_HOTPLUG_STAT);
- if (IS_G4X(dev_priv) ||
IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv))hotplug_status &= HOTPLUG_INT_STATUS_G4X |DP_AUX_CHANNEL_MASK_INT_STATUS_G4X;- else
hotplug_status &= HOTPLUG_INT_STATUS_I915;- if (hotplug_status == 0)
return 0;- spin_lock(&dev_priv->irq_lock);
- /*
* Toggle all PORT_HOTPLUG_EN bits to make sure we* get an edge in the ISR port interrupt bit if we* don't clear all the enabled status bits. Otherwise* the edge triggered IIR on i965/g4x wouldn't notice* that an interrupt is still pending.*/- hotplug_en = I915_READ(PORT_HOTPLUG_EN);
- I915_WRITE(PORT_HOTPLUG_EN, 0);
- I915_WRITE(PORT_HOTPLUG_STAT, hotplug_status);
- I915_WRITE(PORT_HOTPLUG_EN, hotplug_en);
Actually this seems to be a bad idea. At least one elk here likes to signal a long pulse on disconnected ports every time I toggle the enable bit in PORT_HOTPLUG_EN. The spec even warns that something like this could happen. Not sure why it specifically happens for ports where nothing is connected. Feels like it should be the other way around.
So looks like I'll need to come up with some other way to guarantee the ISR edge. Can't immediately think of any way apart from clearing PORT_HOTPLUG_STAT in a loop :(
- spin_unlock(&dev_priv->irq_lock);
return hotplug_status; } -- 2.16.4
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