On Fri, 2018-02-16 at 08:52 +0000, Chris Wilson wrote:
> Quoting Dhinakaran Pandiyan (2018-02-16 04:33:18)
> > i915_gem_obj_pin_to_display() calls frontbuffer_flush with origin set to
> > DIRTYFB. The callers however are at a vantage point to decide if hardware
> > frontbuffer tracking can do the flush for us. For example, legacy cursor
> > updates, like flips, write to MMIO registers, which then triggers PSR flush
> > by the hardware. Moving frontbuffer_flush out will enable us to skip a
> > software initiated flush by setting origin to FLIP. Thanks to Chris for the
> > idea.
> >
> > Cc: Chris Wilson <ch...@chris-wilson.co.uk>
> > Cc: Ville Syrjälä <ville.syrj...@linux.intel.com>
> > Cc: Paulo Zanoni <paulo.r.zan...@intel.com>
> > Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandi...@intel.com>
> > ---
> > drivers/gpu/drm/i915/i915_gem.c | 9 ++++-----
> > drivers/gpu/drm/i915/intel_display.c | 13 ++++++++++---
> > drivers/gpu/drm/i915/intel_fbdev.c | 6 +++---
> > drivers/gpu/drm/i915/intel_overlay.c | 1 +
> > 4 files changed, 18 insertions(+), 11 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/i915_gem.c
> > b/drivers/gpu/drm/i915/i915_gem.c
> > index fc68b35854df..22b598e1e0b9 100644
> > --- a/drivers/gpu/drm/i915/i915_gem.c
> > +++ b/drivers/gpu/drm/i915/i915_gem.c
> > @@ -4071,9 +4071,10 @@ int i915_gem_set_caching_ioctl(struct drm_device
> > *dev, void *data,
> > }
> >
> > /*
> > - * Prepare buffer for display plane (scanout, cursors, etc).
> > - * Can be called from an uninterruptible phase (modesetting) and allows
> > - * any flushes to be pipelined (for pageflips).
> > + * Prepare buffer for display plane (scanout, cursors, etc). Can be called
> > from
> > + * an uninterruptible phase (modesetting) and allows any flushes to be
> > pipelined
> > + * (for pageflips). We only flush the caches while preparing the buffer for
> > + * display, the callers are responsible for frontbuffer flush.
> > */
> > struct i915_vma *
> > i915_gem_object_pin_to_display_plane(struct drm_i915_gem_object *obj,
> > @@ -4139,9 +4140,7 @@ i915_gem_object_pin_to_display_plane(struct
> > drm_i915_gem_object *obj,
> >
> > vma->display_alignment = max_t(u64, vma->display_alignment,
> > alignment);
> >
> > - /* Treat this as an end-of-frame, like
> > intel_user_framebuffer_dirty() */
> > __i915_gem_object_flush_for_display(obj);
> > - intel_fb_obj_flush(obj, ORIGIN_DIRTYFB);
> >
> > /* It should now be out of any other write domains, and we can
> > update
> > * the domain values for our changes.
> > diff --git a/drivers/gpu/drm/i915/intel_display.c
> > b/drivers/gpu/drm/i915/intel_display.c
> > index 286a9591d179..2b70714ead0f 100644
> > --- a/drivers/gpu/drm/i915/intel_display.c
> > +++ b/drivers/gpu/drm/i915/intel_display.c
> > @@ -2806,10 +2806,15 @@ intel_find_initial_plane_obj(struct intel_crtc
> > *intel_crtc,
> > return;
> >
> > valid_fb:
> > + obj = intel_fb_obj(fb);
> > mutex_lock(&dev->struct_mutex);
> > intel_state->vma =
> > intel_pin_and_fence_fb_obj(fb, primary->state->rotation);
> > +
> > + if (!IS_ERR(intel_state->vma))
> > + intel_fb_obj_flush(obj, ORIGIN_DIRTYFB);
>
> The fb_obj_flush doesn't need to be inside the lock, so you can do it
> after the normal error testing (or just do it since the flush doesn't
> depend on having the vma bound).
Okay, that answers the question I meant to ask. Decided to err on the
side of caution.
>
> > mutex_unlock(&dev->struct_mutex);
> > +
> > if (IS_ERR(intel_state->vma)) {
> > DRM_ERROR("failed to pin boot fb on pipe %d: %li\n",
> > intel_crtc->pipe, PTR_ERR(intel_state->vma));
> > @@ -12713,10 +12717,12 @@ intel_prepare_plane_fb(struct drm_plane *plane,
> > struct i915_vma *vma;
> >
> > vma = intel_pin_and_fence_fb_obj(fb, new_state->rotation);
> > - if (!IS_ERR(vma))
> > + if (!IS_ERR(vma)) {
> > to_intel_plane_state(new_state)->vma = vma;
> > - else
> > + intel_fb_obj_flush(obj, ORIGIN_DIRTYFB);
> > + } else {
> > ret = PTR_ERR(vma);
>
> Would
> if (IS_ERR(vma)) {
> ret = PTR_ERR(vma);
> break;
There's no loop around this, but this change goes away in [Patch 4/5].
> }
>
> intel_fb_obj_flush(obj, ORIGIN_DIRTYFB);
> to_intel_plane_state(new_state)->vma = vma;
>
> look neater here?
>
> Lgtm,
> -Chris
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