On Mon, Jun 16, 2014 at 12:30:27PM +0100, oscar.mateo@xxxxxxxxx wrote:
> From: Oscar Mateo <oscar.mateo@xxxxxxxxx>
>
> Otherwise, we might receive a new interrupt before we have time to
> ack the first one, eventually missing it.
>
> Notice that, before clearing a port-sourced interrupt in the IIR, the
> corresponding interrupt source status in the PORT_HOTPLUG_STAT must be
> cleared.
I believe PIPESTAT (and actually all multi-level interrupts) should be
handled the same way.
The way I would write interrupt handlers is something like this:
{
iir = read(IIR);
if (iir & X) {
iir_x = read(IIR_X);
write(IIR_X, iir_x);
}
if (iir & Y) {
iir_y = read(IIR_Y);
write(IIR_Y, iir_y);
}
...
write(IIR, iir);
process_x(iir_x);
process_y(iir_y);
...
}
And then we hope the hardware is sane enough to keep the IIR bit high as
long as the relevant sub-IIR bits are high, and also that the CPU interrupt
would be re-raised if any IIR bits are high when exiting the interrupt
handler. But I have the impression our hardware isn't quite that sane.
>
> Spotted by Bob Beckett <robert.beckett@xxxxxxxxx>.
>
> Signed-off-by: Oscar Mateo <oscar.mateo@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/i915_irq.c | 61 +++++++++++++++++++++++------------------
> 1 file changed, 35 insertions(+), 26 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> index 4439e2d..9d381cc 100644
> --- a/drivers/gpu/drm/i915/i915_irq.c
> +++ b/drivers/gpu/drm/i915/i915_irq.c
> @@ -1813,26 +1813,28 @@ static void i9xx_hpd_irq_handler(struct drm_device *dev)
> struct drm_i915_private *dev_priv = dev->dev_private;
> u32 hotplug_status = I915_READ(PORT_HOTPLUG_STAT);
>
> - if (IS_G4X(dev)) {
> - u32 hotplug_trigger = hotplug_status & HOTPLUG_INT_STATUS_G4X;
> + if (hotplug_status) {
> + I915_WRITE(PORT_HOTPLUG_STAT, hotplug_status);
> + /*
> + * Make sure hotplug status is cleared before we clear IIR, or else we
> + * may miss hotplug events.
> + */
> + POSTING_READ(PORT_HOTPLUG_STAT);
>
> - intel_hpd_irq_handler(dev, hotplug_trigger, hpd_status_g4x);
> - } else {
> - u32 hotplug_trigger = hotplug_status & HOTPLUG_INT_STATUS_I915;
> + if (IS_G4X(dev)) {
> + u32 hotplug_trigger = hotplug_status & HOTPLUG_INT_STATUS_G4X;
>
> - intel_hpd_irq_handler(dev, hotplug_trigger, hpd_status_i915);
> - }
> + intel_hpd_irq_handler(dev, hotplug_trigger, hpd_status_g4x);
> + } else {
> + u32 hotplug_trigger = hotplug_status & HOTPLUG_INT_STATUS_I915;
>
> - if ((IS_G4X(dev) || IS_VALLEYVIEW(dev)) &&
> - hotplug_status & DP_AUX_CHANNEL_MASK_INT_STATUS_G4X)
> - dp_aux_irq_handler(dev);
> + intel_hpd_irq_handler(dev, hotplug_trigger, hpd_status_i915);
> + }
>
> - I915_WRITE(PORT_HOTPLUG_STAT, hotplug_status);
> - /*
> - * Make sure hotplug status is cleared before we clear IIR, or else we
> - * may miss hotplug events.
> - */
> - POSTING_READ(PORT_HOTPLUG_STAT);
> + if ((IS_G4X(dev) || IS_VALLEYVIEW(dev)) &&
> + hotplug_status & DP_AUX_CHANNEL_MASK_INT_STATUS_G4X)
> + dp_aux_irq_handler(dev);
> + }
> }
>
> static irqreturn_t valleyview_irq_handler(int irq, void *arg)
> @@ -1843,29 +1845,36 @@ static irqreturn_t valleyview_irq_handler(int irq, void *arg)
> irqreturn_t ret = IRQ_NONE;
>
> while (true) {
> - iir = I915_READ(VLV_IIR);
> gt_iir = I915_READ(GTIIR);
> pm_iir = I915_READ(GEN6_PMIIR);
> + iir = I915_READ(VLV_IIR);
>
> if (gt_iir == 0 && pm_iir == 0 && iir == 0)
> goto out;
>
> - ret = IRQ_HANDLED;
> + if (gt_iir)
> + I915_WRITE(GTIIR, gt_iir);
>
> - snb_gt_irq_handler(dev, dev_priv, gt_iir);
> + if (pm_iir)
> + I915_WRITE(GEN6_PMIIR, pm_iir);
>
> - valleyview_pipestat_irq_handler(dev, iir);
> + if (iir) {
> + /* Consume port. Then clear IIR or we'll miss events */
> + if (iir & I915_DISPLAY_PORT_INTERRUPT)
> + i9xx_hpd_irq_handler(dev);
> + I915_WRITE(VLV_IIR, iir);
> + }
>
> - /* Consume port. Then clear IIR or we'll miss events */
> - if (iir & I915_DISPLAY_PORT_INTERRUPT)
> - i9xx_hpd_irq_handler(dev);
> + ret = IRQ_HANDLED;
> +
> + if (gt_iir)
> + snb_gt_irq_handler(dev, dev_priv, gt_iir);
>
> if (pm_iir)
> gen6_rps_irq_handler(dev_priv, pm_iir);
>
> - I915_WRITE(GTIIR, gt_iir);
> - I915_WRITE(GEN6_PMIIR, pm_iir);
> - I915_WRITE(VLV_IIR, iir);
> + if (iir)
> + valleyview_pipestat_irq_handler(dev, iir);
> }
>
> out:
> --
> 1.9.0
>
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--
Ville Syrjälä
Intel OTC
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