On Thu, Jun 14, 2018 at 08:56:25PM +0300, Ville Syrjala wrote: > From: Ville Syrjälä <[email protected]> > > 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. Unfortunately > we can't borrow the PIPESTAT trick and toggle the enable > bits in PORT_HOTPLUG_EN as that act itself generates hotplug > interrupts. Instead we just have to loop until we've cleared > PORT_HOTPLUG_STAT, or we just give up and WARN. > > v2: Don't frob with PORT_HOTPLUG_EN > > Cc: [email protected] > Signed-off-by: Ville Syrjälä <[email protected]>
Ok, not so great that we have to loop, but looks like there's no better way to go about it. Good that the problem was root caused: Reviewed-by: Imre Deak <[email protected]> > --- > drivers/gpu/drm/i915/i915_irq.c | 32 ++++++++++++++++++++++++++++++-- > 1 file changed, 30 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c > index d5aee0b74f4b..55a4d4f3fbb2 100644 > --- a/drivers/gpu/drm/i915/i915_irq.c > +++ b/drivers/gpu/drm/i915/i915_irq.c > @@ -1998,10 +1998,38 @@ 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 = 0, hotplug_status_mask; > + int i; > + > + if (IS_G4X(dev_priv) || > + IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv)) > + hotplug_status_mask = HOTPLUG_INT_STATUS_G4X | > + DP_AUX_CHANNEL_MASK_INT_STATUS_G4X; > + else > + hotplug_status_mask = HOTPLUG_INT_STATUS_I915; > > - if (hotplug_status) > + /* > + * We absolutely have to clear all the pending interrupt > + * bits in PORT_HOTPLUG_STAT. Otherwise the ISR port > + * interrupt bit won't have an edge, and the i965/g4x > + * edge triggered IIR will not notice that an interrupt > + * is still pending. We can't use PORT_HOTPLUG_EN to > + * guarantee the edge as the act of toggling the enable > + * bits can itself generate a new hotplug interrupt :( > + */ > + for (i = 0; i < 10; i++) { > + u32 tmp = I915_READ(PORT_HOTPLUG_STAT) & hotplug_status_mask; > + > + if (tmp == 0) > + return hotplug_status; > + > + hotplug_status |= tmp; > I915_WRITE(PORT_HOTPLUG_STAT, hotplug_status); > + } > + > + WARN_ONCE(1, > + "PORT_HOTPLUG_STAT did not clear (0x%08x)\n", > + I915_READ(PORT_HOTPLUG_STAT)); > > return hotplug_status; > } > -- > 2.16.4 > > _______________________________________________ > Intel-gfx mailing list > [email protected] > https://lists.freedesktop.org/mailman/listinfo/intel-gfx _______________________________________________ Intel-gfx mailing list [email protected] https://lists.freedesktop.org/mailman/listinfo/intel-gfx
