On Mon, Jun 16, 2014 at 04:10:59PM +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.
>
> The right order should be:
>
> 1 - Disable Master Interrupt Control.
> 2 - Find the category of interrupt that is pending.
> 3 - Find the source(s) of the interrupt and clear the Interrupt Identity bits (IIR)
> 4 - Process the interrupt(s) that had bits set in the IIRs.
> 5 - Re-enable Master Interrupt Control.
>
> Without an atomic XCHG operation with mmio space, the above merely reduces the window
> in which we can miss an interrupt (especially when you consider how heavyweight the
> I915_READ/I915_WRITE operations are).
>
> Spotted by Bob Beckett <robert.beckett@xxxxxxxxx>.
>
> v2: Add warning to commit message and comments to the code as per Chris Wilson's request.
>
> v3: Improve the source code comment.
>
> Signed-off-by: Oscar Mateo <oscar.mateo@xxxxxxxxx>
This one had a small conflict with Chris' stall detection patch that I
fixed up while applying. Entire series merged, thanks.
-Daniel
> ---
> drivers/gpu/drm/i915/i915_irq.c | 91 ++++++++++++++++++++---------------------
> 1 file changed, 45 insertions(+), 46 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> index 20f7c05..46fe3ad 100644
> --- a/drivers/gpu/drm/i915/i915_irq.c
> +++ b/drivers/gpu/drm/i915/i915_irq.c
> @@ -1462,6 +1462,7 @@ static irqreturn_t gen8_gt_irq_handler(struct drm_device *dev,
> if (master_ctl & (GEN8_GT_RCS_IRQ | GEN8_GT_BCS_IRQ)) {
> tmp = I915_READ(GEN8_GT_IIR(0));
> if (tmp) {
> + I915_WRITE(GEN8_GT_IIR(0), tmp);
> ret = IRQ_HANDLED;
> rcs = tmp >> GEN8_RCS_IRQ_SHIFT;
> bcs = tmp >> GEN8_BCS_IRQ_SHIFT;
> @@ -1469,7 +1470,6 @@ static irqreturn_t gen8_gt_irq_handler(struct drm_device *dev,
> notify_ring(dev, &dev_priv->ring[RCS]);
> if (bcs & GT_RENDER_USER_INTERRUPT)
> notify_ring(dev, &dev_priv->ring[BCS]);
> - I915_WRITE(GEN8_GT_IIR(0), tmp);
> } else
> DRM_ERROR("The master control interrupt lied (GT0)!\n");
> }
> @@ -1477,6 +1477,7 @@ static irqreturn_t gen8_gt_irq_handler(struct drm_device *dev,
> if (master_ctl & (GEN8_GT_VCS1_IRQ | GEN8_GT_VCS2_IRQ)) {
> tmp = I915_READ(GEN8_GT_IIR(1));
> if (tmp) {
> + I915_WRITE(GEN8_GT_IIR(1), tmp);
> ret = IRQ_HANDLED;
> vcs = tmp >> GEN8_VCS1_IRQ_SHIFT;
> if (vcs & GT_RENDER_USER_INTERRUPT)
> @@ -1484,7 +1485,6 @@ static irqreturn_t gen8_gt_irq_handler(struct drm_device *dev,
> vcs = tmp >> GEN8_VCS2_IRQ_SHIFT;
> if (vcs & GT_RENDER_USER_INTERRUPT)
> notify_ring(dev, &dev_priv->ring[VCS2]);
> - I915_WRITE(GEN8_GT_IIR(1), tmp);
> } else
> DRM_ERROR("The master control interrupt lied (GT1)!\n");
> }
> @@ -1492,10 +1492,10 @@ static irqreturn_t gen8_gt_irq_handler(struct drm_device *dev,
> if (master_ctl & GEN8_GT_PM_IRQ) {
> tmp = I915_READ(GEN8_GT_IIR(2));
> if (tmp & dev_priv->pm_rps_events) {
> - ret = IRQ_HANDLED;
> - gen8_rps_irq_handler(dev_priv, tmp);
> I915_WRITE(GEN8_GT_IIR(2),
> tmp & dev_priv->pm_rps_events);
> + ret = IRQ_HANDLED;
> + gen8_rps_irq_handler(dev_priv, tmp);
> } else
> DRM_ERROR("The master control interrupt lied (PM)!\n");
> }
> @@ -1503,11 +1503,11 @@ static irqreturn_t gen8_gt_irq_handler(struct drm_device *dev,
> if (master_ctl & GEN8_GT_VECS_IRQ) {
> tmp = I915_READ(GEN8_GT_IIR(3));
> if (tmp) {
> + I915_WRITE(GEN8_GT_IIR(3), tmp);
> ret = IRQ_HANDLED;
> vcs = tmp >> GEN8_VECS_IRQ_SHIFT;
> if (vcs & GT_RENDER_USER_INTERRUPT)
> notify_ring(dev, &dev_priv->ring[VECS]);
> - I915_WRITE(GEN8_GT_IIR(3), tmp);
> } else
> DRM_ERROR("The master control interrupt lied (GT3)!\n");
> }
> @@ -2238,36 +2238,36 @@ static irqreturn_t gen8_irq_handler(int irq, void *arg)
> I915_WRITE(GEN8_MASTER_IRQ, 0);
> POSTING_READ(GEN8_MASTER_IRQ);
>
> + /* Find, clear, then process each source of interrupt */
> +
> ret = gen8_gt_irq_handler(dev, dev_priv, master_ctl);
>
> if (master_ctl & GEN8_DE_MISC_IRQ) {
> tmp = I915_READ(GEN8_DE_MISC_IIR);
> - if (tmp & GEN8_DE_MISC_GSE)
> - intel_opregion_asle_intr(dev);
> - else if (tmp)
> - DRM_ERROR("Unexpected DE Misc interrupt\n");
> - else
> - DRM_ERROR("The master control interrupt lied (DE MISC)!\n");
> -
> if (tmp) {
> I915_WRITE(GEN8_DE_MISC_IIR, tmp);
> ret = IRQ_HANDLED;
> + if (tmp & GEN8_DE_MISC_GSE)
> + intel_opregion_asle_intr(dev);
> + else
> + DRM_ERROR("Unexpected DE Misc interrupt\n");
> }
> + else
> + DRM_ERROR("The master control interrupt lied (DE MISC)!\n");
> }
>
> if (master_ctl & GEN8_DE_PORT_IRQ) {
> tmp = I915_READ(GEN8_DE_PORT_IIR);
> - if (tmp & GEN8_AUX_CHANNEL_A)
> - dp_aux_irq_handler(dev);
> - else if (tmp)
> - DRM_ERROR("Unexpected DE Port interrupt\n");
> - else
> - DRM_ERROR("The master control interrupt lied (DE PORT)!\n");
> -
> if (tmp) {
> I915_WRITE(GEN8_DE_PORT_IIR, tmp);
> ret = IRQ_HANDLED;
> + if (tmp & GEN8_AUX_CHANNEL_A)
> + dp_aux_irq_handler(dev);
> + else
> + DRM_ERROR("Unexpected DE Port interrupt\n");
> }
> + else
> + DRM_ERROR("The master control interrupt lied (DE PORT)!\n");
> }
>
> for_each_pipe(pipe) {
> @@ -2277,33 +2277,32 @@ static irqreturn_t gen8_irq_handler(int irq, void *arg)
> continue;
>
> pipe_iir = I915_READ(GEN8_DE_PIPE_IIR(pipe));
> - if (pipe_iir & GEN8_PIPE_VBLANK)
> - intel_pipe_handle_vblank(dev, pipe);
> -
> - if (pipe_iir & GEN8_PIPE_PRIMARY_FLIP_DONE) {
> - intel_prepare_page_flip(dev, pipe);
> - intel_finish_page_flip_plane(dev, pipe);
> - }
> + if (pipe_iir) {
> + ret = IRQ_HANDLED;
> + I915_WRITE(GEN8_DE_PIPE_IIR(pipe), pipe_iir);
> + if (pipe_iir & GEN8_PIPE_VBLANK)
> + intel_pipe_handle_vblank(dev, pipe);
>
> - if (pipe_iir & GEN8_PIPE_CDCLK_CRC_DONE)
> - hsw_pipe_crc_irq_handler(dev, pipe);
> + if (pipe_iir & GEN8_PIPE_PRIMARY_FLIP_DONE) {
> + intel_prepare_page_flip(dev, pipe);
> + intel_finish_page_flip_plane(dev, pipe);
> + }
>
> - if (pipe_iir & GEN8_PIPE_FIFO_UNDERRUN) {
> - if (intel_set_cpu_fifo_underrun_reporting(dev, pipe,
> - false))
> - DRM_ERROR("Pipe %c FIFO underrun\n",
> - pipe_name(pipe));
> - }
> + if (pipe_iir & GEN8_PIPE_CDCLK_CRC_DONE)
> + hsw_pipe_crc_irq_handler(dev, pipe);
>
> - if (pipe_iir & GEN8_DE_PIPE_IRQ_FAULT_ERRORS) {
> - DRM_ERROR("Fault errors on pipe %c\n: 0x%08x",
> - pipe_name(pipe),
> - pipe_iir & GEN8_DE_PIPE_IRQ_FAULT_ERRORS);
> - }
> + if (pipe_iir & GEN8_PIPE_FIFO_UNDERRUN) {
> + if (intel_set_cpu_fifo_underrun_reporting(dev, pipe,
> + false))
> + DRM_ERROR("Pipe %c FIFO underrun\n",
> + pipe_name(pipe));
> + }
>
> - if (pipe_iir) {
> - ret = IRQ_HANDLED;
> - I915_WRITE(GEN8_DE_PIPE_IIR(pipe), pipe_iir);
> + if (pipe_iir & GEN8_DE_PIPE_IRQ_FAULT_ERRORS) {
> + DRM_ERROR("Fault errors on pipe %c\n: 0x%08x",
> + pipe_name(pipe),
> + pipe_iir & GEN8_DE_PIPE_IRQ_FAULT_ERRORS);
> + }
> } else
> DRM_ERROR("The master control interrupt lied (DE PIPE)!\n");
> }
> @@ -2315,13 +2314,13 @@ static irqreturn_t gen8_irq_handler(int irq, void *arg)
> * on older pch-split platforms. But this needs testing.
> */
> u32 pch_iir = I915_READ(SDEIIR);
> -
> - cpt_irq_handler(dev, pch_iir);
> -
> if (pch_iir) {
> I915_WRITE(SDEIIR, pch_iir);
> ret = IRQ_HANDLED;
> - }
> + cpt_irq_handler(dev, pch_iir);
> + } else
> + DRM_ERROR("The master control interrupt lied (SDE)!\n");
> +
> }
>
> I915_WRITE(GEN8_MASTER_IRQ, GEN8_MASTER_IRQ_CONTROL);
> --
> 1.9.0
>
> _______________________________________________
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> Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx
--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
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