Op 20-02-17 om 14:38 schreef Ville Syrjälä:
> On Mon, Feb 20, 2017 at 10:04:06AM +0100, Maarten Lankhorst wrote:
>> Op 17-02-17 om 16:01 schreef ville.syrjala@xxxxxxxxxxxxxxx:
>>> From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
>>>
>>> In order to make cursor updates actually safe wrt. watermark programming
>>> we have to clear the legacy_cursor_update flag in the atomic state. That
>>> will cause the regular atomic update path to do the necessary vblank
>>> wait after the plane update if needed, otherwise the vblank wait would
>>> be skipped and we'd feed the optimal watermarks to the hardware before
>>> the plane update has actually happened.
>>>
>>> To make the slow vs. fast path determination in
>>> intel_legacy_cursor_update() a little simpler we can ignore the actual
>>> visibility of the plane (which can only get computed once we've already
>>> chosen out path) and instead we simply check whether the fb is being
>>> set or cleared by the user. This means a fully clipped but logically
>>> visible cursor will be considered visible as far as watermark
>>> programming is concerned. We can do that for the cursor since it's a
>>> fixed size plane and the clipped size doesn't play a role in the
>>> watermark computation.
>>>
>>> This should fix underruns that can occur when the cursor gets
>>> enable/disabled or the size gets changed. Hopefully it's good enough
>>> that only pure cursor movement and flips go through unthrottled.
>>>
>>> Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
>>> Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
>>> Cc: Uwe Kleine-König <uwe@xxxxxxxxxxxxxxxxx>
>>> Reported-by: Uwe Kleine-König <uwe@xxxxxxxxxxxxxxxxx>
>>> Fixes: f79f26921ee1 ("drm/i915: Add a cursor hack to allow converting legacy page flip to atomic, v3.")
>>> Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
>>> ---
>>> drivers/gpu/drm/i915/intel_display.c | 29 ++++++++++++++++++-----------
>>> drivers/gpu/drm/i915/intel_pm.c | 20 ++++++++++++--------
>>> 2 files changed, 30 insertions(+), 19 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
>>> index b05d9c85384b..356ac04093e8 100644
>>> --- a/drivers/gpu/drm/i915/intel_display.c
>>> +++ b/drivers/gpu/drm/i915/intel_display.c
>>> @@ -13031,6 +13031,17 @@ static int intel_atomic_commit(struct drm_device *dev,
>>> struct drm_i915_private *dev_priv = to_i915(dev);
>>> int ret = 0;
>>>
>>> + /*
>>> + * The intel_legacy_cursor_update() fast path takes care
>>> + * of avoiding the vblank waits for simple cursor
>>> + * movement and flips. For cursor on/off and size changes,
>>> + * we want to perform the vblank waits so that watermark
>>> + * updates happen during the correct frames. Gen9+ have
>>> + * double buffered watermarks and so shouldn't need this.
>>> + */
>>> + if (INTEL_GEN(dev_priv) < 9)
>>> + state->legacy_cursor_update = false;
>> Could we perhaps add a check in ilk_compute_pipe_wm which unsets the legacy_cursor_update flag so we keep things unsynced as much as possible?
> I'd have to sprinkle that stuff everywhere but the SKL code
> eventually. Seems a little pointless when I can just plop it
> there.
Ah indeed. Lets hope it doesn't slow things down too much.
>>> ret = drm_atomic_helper_setup_commit(state, nonblock);
>>> if (ret)
>>> return ret;
>>> @@ -13455,8 +13466,7 @@ intel_legacy_cursor_update(struct drm_plane *plane,
>>> old_plane_state->src_h != src_h ||
>>> old_plane_state->crtc_w != crtc_w ||
>>> old_plane_state->crtc_h != crtc_h ||
>>> - !old_plane_state->visible ||
>>> - old_plane_state->fb->modifier != fb->modifier)
>>> + !old_plane_state->fb != !fb)
>>> goto slow;
>>>
>>> new_plane_state = intel_plane_duplicate_state(plane);
>>> @@ -13479,10 +13489,6 @@ intel_legacy_cursor_update(struct drm_plane *plane,
>>> if (ret)
>>> goto out_free;
>>>
>>> - /* Visibility changed, must take slowpath. */
>>> - if (!new_plane_state->visible)
>>> - goto slow_free;
>>> -
>>> ret = mutex_lock_interruptible(&dev_priv->drm.struct_mutex);
>>> if (ret)
>>> goto out_free;
>> Those 2 hunks are needed. If you move the cursor out of the visible area or back you need to update.
> No. I changed the wm code to consider a non-visible but logicall active
> cursor as needing proper watermarks. That avoids needing this fallback
> path here.
Ah indeed. But one thing you dropped is the fb modifier check.
I suppose there's no harm with no support for using prite planes as cursor plane yet, but might be nice to keep it in.
Cc'ing Ristovski for testing the patch. :)
>
>> Easiest way to trigger a bug is load a 256 width cursor out of the visible area, move it back in and you get
>> a fifo underrun.
>>
>> Why is switching fb's synced?
> It is not.
>
>> Identical sized fb should be unsynced if possible.
>>
>>> @@ -13522,9 +13528,12 @@ intel_legacy_cursor_update(struct drm_plane *plane,
>>> new_plane_state->fb = old_fb;
>>> to_intel_plane_state(new_plane_state)->vma = old_vma;
>>>
>>> - intel_plane->update_plane(plane,
>>> - to_intel_crtc_state(crtc->state),
>>> - to_intel_plane_state(plane->state));
>>> + if (plane->state->visible)
>>> + intel_plane->update_plane(plane,
>>> + to_intel_crtc_state(crtc->state),
>>> + to_intel_plane_state(plane->state));
>>> + else
>>> + intel_plane->disable_plane(plane, crtc);
>>>
>>> intel_cleanup_plane_fb(plane, new_plane_state);
>>>
>>> @@ -13534,8 +13543,6 @@ intel_legacy_cursor_update(struct drm_plane *plane,
>>> intel_plane_destroy_state(plane, new_plane_state);
>>> return ret;
>>>
>>> -slow_free:
>>> - intel_plane_destroy_state(plane, new_plane_state);
>>> slow:
>>> return drm_atomic_helper_update_plane(plane, crtc, fb,
>>> crtc_x, crtc_y, crtc_w, crtc_h,
>>> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
>>> index fe243c65de1a..4de8c40acc7e 100644
>>> --- a/drivers/gpu/drm/i915/intel_pm.c
>>> +++ b/drivers/gpu/drm/i915/intel_pm.c
>>> @@ -1831,20 +1831,24 @@ static uint32_t ilk_compute_cur_wm(const struct intel_crtc_state *cstate,
>>> const struct intel_plane_state *pstate,
>>> uint32_t mem_value)
>>> {
>>> + int cpp;
>>> +
>>> /*
>>> - * We treat the cursor plane as always-on for the purposes of watermark
>>> - * calculation. Until we have two-stage watermark programming merged,
>>> - * this is necessary to avoid flickering.
>>> + * Treat cursor with fb as always visible since cursor updates
>>> + * can happen faster than the vrefresh rate, and the current
>>> + * watermark code doesn't handle that correctly. Cursor updates
>>> + * which set/clear the fb or change the cursor size are going
>>> + * to get throttled by intel_legacy_cursor_update() to work
>>> + * around this problem with the watermark code.
>>> */
>>> - int cpp = 4;
>>> - int width = pstate->base.visible ? pstate->base.crtc_w : 64;
>>> -
>>> - if (!cstate->base.active)
>>> + if (!cstate->base.active || !pstate->base.fb)
>>> return 0;
>>>
>>> + cpp = pstate->base.fb->format->cpp[0];
>>> +
>>> return ilk_wm_method2(cstate->pixel_rate,
>>> cstate->base.adjusted_mode.crtc_htotal,
>>> - width, cpp, mem_value);
>>> + pstate->base.crtc_w, cpp, mem_value);
>>> }
>>>
>>> /* Only for WM_LP. */
_______________________________________________
Intel-gfx mailing list
Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
https://lists.freedesktop.org/mailman/listinfo/intel-gfx
