Am Montag, den 18.02.2013, 13:57 +0200 schrieb ville.syrjala at linux.intel.com:
> From: Ville Syrj?l? <ville.syrjala at linux.intel.com>
>
> If the interrupt handler were to process a previous vblank interrupt and
> the following flip pending interrupt at the same time, the page flip
> would be complete too soon.
?would complete? or ?would be complete*d*?
> To eliminate this race check the live pending flip status from the ISR
> register before finishing the page flip.
Could this be tested somehow? Could a test case be written for this?
> Signed-off-by: Ville Syrj?l? <ville.syrjala at linux.intel.com>
> ---
> drivers/gpu/drm/i915/i915_irq.c | 21 +++++++++++++++------
> 1 file changed, 15 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> index 9fde49a..3de570c 100644
> --- a/drivers/gpu/drm/i915/i915_irq.c
> +++ b/drivers/gpu/drm/i915/i915_irq.c
> @@ -2284,8 +2284,11 @@ static irqreturn_t i8xx_irq_handler(int irq, void *arg)
> drm_handle_vblank(dev, 0)) {
> if (iir & I915_DISPLAY_PLANE_A_FLIP_PENDING_INTERRUPT) {
> intel_prepare_page_flip(dev, 0);
> - intel_finish_page_flip(dev, 0);
> - flip_mask &= ~I915_DISPLAY_PLANE_A_FLIP_PENDING_INTERRUPT;
> +
> + if ((I915_READ16(ISR) & I915_DISPLAY_PLANE_A_FLIP_PENDING_INTERRUPT) == 0) {
> + intel_finish_page_flip(dev, 0);
> + flip_mask &= ~I915_DISPLAY_PLANE_A_FLIP_PENDING_INTERRUPT;
> + }
> }
> }
>
> @@ -2293,8 +2296,11 @@ static irqreturn_t i8xx_irq_handler(int irq, void *arg)
> drm_handle_vblank(dev, 1)) {
> if (iir & I915_DISPLAY_PLANE_B_FLIP_PENDING_INTERRUPT) {
> intel_prepare_page_flip(dev, 1);
> - intel_finish_page_flip(dev, 1);
> - flip_mask &= ~I915_DISPLAY_PLANE_B_FLIP_PENDING_INTERRUPT;
> +
> + if ((I915_READ16(ISR) & I915_DISPLAY_PLANE_B_FLIP_PENDING_INTERRUPT) == 0) {
> + intel_finish_page_flip(dev, 1);
> + flip_mask &= ~I915_DISPLAY_PLANE_B_FLIP_PENDING_INTERRUPT;
> + }
> }
> }
>
> @@ -2491,8 +2497,11 @@ static irqreturn_t i915_irq_handler(int irq, void *arg)
> drm_handle_vblank(dev, pipe)) {
> if (iir & flip[plane]) {
> intel_prepare_page_flip(dev, plane);
> - intel_finish_page_flip(dev, pipe);
> - flip_mask &= ~flip[plane];
> +
> + if ((I915_READ(ISR) & flip[plane]) == 0) {
Why not `I915_READ16`?
> + intel_finish_page_flip(dev, pipe);
> + flip_mask &= ~flip[plane];
> + }
> }
> }
Thanks,
Paul
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 198 bytes
Desc: This is a digitally signed message part
URL: <http://lists.freedesktop.org/archives/intel-gfx/attachments/20130218/7ee1dc90/attachment.pgp>
