[PATCH] drm/amd/display: Fix vblank and pageflip event handling for FreeSync
Kazlauskas, Nicholas
nicholas.kazlauskas at amd.com
Thu May 7 17:35:20 UTC 2020
It applies on top of Alex's amd-staging-drm-next-branch.
It is essentially just a revert to the old behavior with
acrtc_state->active_planes == 0 special case you added on top and some
small refactoring.
The only remaining bits that are kind of questionable is the
VUPDATE_NO_LOCK vs VUPDATE bit again along with some of the locking
around where we check if FreeSync is active or not.
I also don't think that VSTARTUP is the correct place to be performing
the update for the registers since the offset between VSTARTUP and
VUPDATE can be small enough such that the programming won't finish in
time for some timings. We should be doing it on line 0 instead.
All these issues existed before this patch series at least though.
Regards,
Nicholas Kazlauskas
On 2020-05-07 12:58 p.m., Mario Kleiner wrote:
> Looking over it now, will do some testing. Alex amdgpu-drm-next branch
> would be the best to test this?
>
> It looks like a revert of the whole vstartup series, except for that
> one if(acrtc_state->active_planes == 0) special case, so i expect it
> should be fine?
>
> thanks,
> -mario
>
>
> On Thu, May 7, 2020 at 5:56 PM Leo Li <sunpeng.li at amd.com
> <mailto:sunpeng.li at amd.com>> wrote:
>
>
>
> On 2020-05-06 3:47 p.m., Nicholas Kazlauskas wrote:
> > [Why]
> > We're the drm vblank event a frame too early in the case where the
> ^sending
>
> Thanks for catching this!
>
> Reviewed-by: Leo Li <sunpeng.li at amd.com <mailto:sunpeng.li at amd.com>>
>
> > pageflip happens close to VUPDATE and ends up blocking the signal.
> >
> > The implementation in DM was previously correct *before* we started
> > sending vblank events from VSTARTUP unconditionally to handle cases
> > where HUBP was off, OTG was ON and userspace was still
> requesting some
> > DRM planes enabled. As part of that patch series we dropped VUPDATE
> > since it was deemed close enough to VSTARTUP, but there's a key
> > difference betweeen VSTARTUP and VUPDATE - the VUPDATE signal can be
> > blocked if we're holding the pipe lock >
> > There was a fix recently to revert the unconditional behavior
> for the
> > DCN VSTARTUP vblank event since it was sending the pageflip event on
> > the wrong frame - once again, due to blocking VUPDATE and having the
> > address start scanning out two frames later.
> >
> > The problem with this fix is it didn't update the logic that calls
> > drm_crtc_handle_vblank(), so the timestamps are totally bogus now.
> >
> > [How]
> > Essentially reverts most of the original VSTARTUP series but retains
> > the behavior to send back events when active planes == 0.
> >
> > Some refactoring/cleanup was done to not have duplicated code in
> both
> > the handlers.
> >
> > Fixes: 16f17eda8bad ("drm/amd/display: Send vblank and user
> events at vsartup for DCN")
> > Fixes: 3a2ce8d66a4b ("drm/amd/display: Disable VUpdate interrupt
> for DCN hardware")
> > Fixes: 2b5aed9ac3f7 ("drm/amd/display: Fix pageflip event race
> condition for DCN.")
> >
> > Cc: Leo Li <sunpeng.li at amd.com <mailto:sunpeng.li at amd.com>>
> > Cc: Mario Kleiner <mario.kleiner.de at gmail.com
> <mailto:mario.kleiner.de at gmail.com>>
> > Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas at amd.com
> <mailto:nicholas.kazlauskas at amd.com>>
> > ---
> > .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 137
> +++++++-----------
> > 1 file changed, 55 insertions(+), 82 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> > index 59f1d4a94f12..30ce28f7c444 100644
> > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> > @@ -441,7 +441,7 @@ static void dm_vupdate_high_irq(void
> *interrupt_params)
> >
> > /**
> > * dm_crtc_high_irq() - Handles CRTC interrupt
> > - * @interrupt_params: ignored
> > + * @interrupt_params: used for determining the CRTC instance
> > *
> > * Handles the CRTC/VSYNC interrupt by notfying DRM's VBLANK
> > * event handler.
> > @@ -455,70 +455,6 @@ static void dm_crtc_high_irq(void
> *interrupt_params)
> > unsigned long flags;
> >
> > acrtc = get_crtc_by_otg_inst(adev, irq_params->irq_src -
> IRQ_TYPE_VBLANK);
> > -
> > - if (acrtc) {
> > - acrtc_state = to_dm_crtc_state(acrtc->base.state);
> > -
> > - DRM_DEBUG_VBL("crtc:%d, vupdate-vrr:%d\n",
> > - acrtc->crtc_id,
> > - amdgpu_dm_vrr_active(acrtc_state));
> > -
> > - /* Core vblank handling at start of front-porch is
> only possible
> > - * in non-vrr mode, as only there vblank
> timestamping will give
> > - * valid results while done in front-porch.
> Otherwise defer it
> > - * to dm_vupdate_high_irq after end of front-porch.
> > - */
> > - if (!amdgpu_dm_vrr_active(acrtc_state))
> > - drm_crtc_handle_vblank(&acrtc->base);
> > -
> > - /* Following stuff must happen at start of vblank,
> for crc
> > - * computation and below-the-range btr support in
> vrr mode.
> > - */
> > - amdgpu_dm_crtc_handle_crc_irq(&acrtc->base);
> > -
> > - if (acrtc_state->stream && adev->family >=
> AMDGPU_FAMILY_AI &&
> > - acrtc_state->vrr_params.supported &&
> > - acrtc_state->freesync_config.state ==
> VRR_STATE_ACTIVE_VARIABLE) {
> > - spin_lock_irqsave(&adev->ddev->event_lock, flags);
> > - mod_freesync_handle_v_update(
> > - adev->dm.freesync_module,
> > - acrtc_state->stream,
> > - &acrtc_state->vrr_params);
> > -
> > - dc_stream_adjust_vmin_vmax(
> > - adev->dm.dc,
> > - acrtc_state->stream,
> > - &acrtc_state->vrr_params.adjust);
> > - spin_unlock_irqrestore(&adev->ddev->event_lock, flags);
> > - }
> > - }
> > -}
> > -
> > -#if defined(CONFIG_DRM_AMD_DC_DCN)
> > -/**
> > - * dm_dcn_crtc_high_irq() - Handles VStartup interrupt for DCN
> generation ASICs
> > - * @interrupt params - interrupt parameters
> > - *
> > - * Notify DRM's vblank event handler at VSTARTUP
> > - *
> > - * Unlike DCE hardware, we trigger the handler at VSTARTUP. at
> which:
> > - * * We are close enough to VUPDATE - the point of no return for hw
> > - * * We are in the fixed portion of variable front porch when
> vrr is enabled
> > - * * We are before VUPDATE, where double-buffered vrr registers
> are swapped
> > - *
> > - * It is therefore the correct place to signal vblank, send
> user flip events,
> > - * and update VRR.
> > - */
> > -static void dm_dcn_crtc_high_irq(void *interrupt_params)
> > -{
> > - struct common_irq_params *irq_params = interrupt_params;
> > - struct amdgpu_device *adev = irq_params->adev;
> > - struct amdgpu_crtc *acrtc;
> > - struct dm_crtc_state *acrtc_state;
> > - unsigned long flags;
> > -
> > - acrtc = get_crtc_by_otg_inst(adev, irq_params->irq_src -
> IRQ_TYPE_VBLANK);
> > -
> > if (!acrtc)
> > return;
> >
> > @@ -528,22 +464,35 @@ static void dm_dcn_crtc_high_irq(void
> *interrupt_params)
> > amdgpu_dm_vrr_active(acrtc_state),
> > acrtc_state->active_planes);
> >
> > + /**
> > + * Core vblank handling at start of front-porch is only
> possible
> > + * in non-vrr mode, as only there vblank timestamping will
> give
> > + * valid results while done in front-porch. Otherwise defer it
> > + * to dm_vupdate_high_irq after end of front-porch.
> > + */
> > + if (!amdgpu_dm_vrr_active(acrtc_state))
> > + drm_crtc_handle_vblank(&acrtc->base);
> > +
> > + /**
> > + * Following stuff must happen at start of vblank, for crc
> > + * computation and below-the-range btr support in vrr mode.
> > + */
> > amdgpu_dm_crtc_handle_crc_irq(&acrtc->base);
> > - drm_crtc_handle_vblank(&acrtc->base);
> > +
> > + /* BTR updates need to happen before VUPDATE on Vega and
> above. */
> > + if (adev->family < AMDGPU_FAMILY_AI)
> > + return;
> >
> > spin_lock_irqsave(&adev->ddev->event_lock, flags);
> >
> > - if (acrtc_state->vrr_params.supported &&
> > + if (acrtc_state->stream &&
> acrtc_state->vrr_params.supported &&
> > acrtc_state->freesync_config.state ==
> VRR_STATE_ACTIVE_VARIABLE) {
> > - mod_freesync_handle_v_update(
> > - adev->dm.freesync_module,
> > - acrtc_state->stream,
> > - &acrtc_state->vrr_params);
> > + mod_freesync_handle_v_update(adev->dm.freesync_module,
> > + acrtc_state->stream,
> > + &acrtc_state->vrr_params);
> >
> > - dc_stream_adjust_vmin_vmax(
> > - adev->dm.dc,
> > - acrtc_state->stream,
> > - &acrtc_state->vrr_params.adjust);
> > + dc_stream_adjust_vmin_vmax(adev->dm.dc,
> acrtc_state->stream,
> > + &acrtc_state->vrr_params.adjust);
> > }
> >
> > /*
> > @@ -556,7 +505,8 @@ static void dm_dcn_crtc_high_irq(void
> *interrupt_params)
> > * avoid race conditions between flip programming and
> completion,
> > * which could cause too early flip completion events.
> > */
> > - if (acrtc->pflip_status == AMDGPU_FLIP_SUBMITTED &&
> > + if (adev->family >= AMDGPU_FAMILY_RV &&
> > + acrtc->pflip_status == AMDGPU_FLIP_SUBMITTED &&
> > acrtc_state->active_planes == 0) {
> > if (acrtc->event) {
> > drm_crtc_send_vblank_event(&acrtc->base, acrtc->event);
> > @@ -568,7 +518,6 @@ static void dm_dcn_crtc_high_irq(void
> *interrupt_params)
> >
> > spin_unlock_irqrestore(&adev->ddev->event_lock, flags);
> > }
> > -#endif
> >
> > static int dm_set_clockgating_state(void *handle,
> > enum amd_clockgating_state state)
> > @@ -2454,8 +2403,36 @@ static int
> dcn10_register_irq_handlers(struct amdgpu_device *adev)
> > c_irq_params->adev = adev;
> > c_irq_params->irq_src = int_params.irq_source;
> >
> > + amdgpu_dm_irq_register_interrupt(
> > + adev, &int_params, dm_crtc_high_irq,
> c_irq_params);
> > + }
> > +
> > + /* Use VUPDATE_NO_LOCK interrupt on DCN, which seems to
> correspond to
> > + * the regular VUPDATE interrupt on DCE. We want
> DC_IRQ_SOURCE_VUPDATEx
> > + * to trigger at end of each vblank, regardless of state
> of the lock,
> > + * matching DCE behaviour.
> > + */
> > + for (i = DCN_1_0__SRCID__OTG0_IHC_V_UPDATE_NO_LOCK_INTERRUPT;
> > + i <=
> DCN_1_0__SRCID__OTG0_IHC_V_UPDATE_NO_LOCK_INTERRUPT +
> adev->mode_info.num_crtc - 1;
> > + i++) {
> > + r = amdgpu_irq_add_id(adev, SOC15_IH_CLIENTID_DCE,
> i, &adev->vupdate_irq);
> > +
> > + if (r) {
> > + DRM_ERROR("Failed to add vupdate irq id!\n");
> > + return r;
> > + }
> > +
> > + int_params.int_context = INTERRUPT_HIGH_IRQ_CONTEXT;
> > + int_params.irq_source =
> > + dc_interrupt_to_irq_source(dc, i, 0);
> > +
> > + c_irq_params =
> &adev->dm.vupdate_params[int_params.irq_source -
> DC_IRQ_SOURCE_VUPDATE1];
> > +
> > + c_irq_params->adev = adev;
> > + c_irq_params->irq_src = int_params.irq_source;
> > +
> > amdgpu_dm_irq_register_interrupt(adev, &int_params,
> > - dm_dcn_crtc_high_irq, c_irq_params);
> > + dm_vupdate_high_irq, c_irq_params);
> > }
> >
> > /* Use GRPH_PFLIP interrupt */
> > @@ -4544,10 +4521,6 @@ static inline int
> dm_set_vupdate_irq(struct drm_crtc *crtc, bool enable)
> > struct amdgpu_device *adev = crtc->dev->dev_private;
> > int rc;
> >
> > - /* Do not set vupdate for DCN hardware */
> > - if (adev->family > AMDGPU_FAMILY_AI)
> > - return 0;
> > -
> > irq_source = IRQ_TYPE_VUPDATE + acrtc->otg_inst;
> >
> > rc = dc_interrupt_set(adev->dm.dc, irq_source, enable) ? 0
> : -EBUSY;
> >
>
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