[Intel-gfx] [PATCH v3 1/5] drm/i915: Add enable/disable flip done and flip done handler
Karthik B S
karthik.b.s at intel.com
Wed Jun 24 11:29:14 UTC 2020
On 6/17/2020 8:15 PM, Kazlauskas, Nicholas wrote:
> On 2020-06-17 5:58 a.m., Daniel Vetter wrote:
>> On Wed, Jun 10, 2020 at 03:33:06PM -0700, Paulo Zanoni wrote:
>>> Em qui, 2020-05-28 às 11:09 +0530, Karthik B S escreveu:
>>>> Add enable/disable flip done functions and the flip done handler
>>>> function which handles the flip done interrupt.
>>>>
>>>> Enable the flip done interrupt in IER.
>>>>
>>>> Enable flip done function is called before writing the
>>>> surface address register as the write to this register triggers
>>>> the flip done interrupt
>>>>
>>>> Flip done handler is used to send the page flip event as soon as the
>>>> surface address is written as per the requirement of async flips.
>>>> The interrupt is disabled after the event is sent.
>>>>
>>>> v2: -Change function name from icl_* to skl_* (Paulo)
>>>> -Move flip handler to this patch (Paulo)
>>>> -Remove vblank_put() (Paulo)
>>>> -Enable flip done interrupt for gen9+ only (Paulo)
>>>> -Enable flip done interrupt in power_well_post_enable hook (Paulo)
>>>> -Removed the event check in flip done handler to handle async
>>>> flips without pageflip events.
>>>>
>>>> v3: -Move skl_disable_flip_done out of interrupt handler (Paulo)
>>>> -Make the pending vblank event NULL in the begining of
>>>> flip_done_handler to remove sporadic WARN_ON that is seen.
>>>>
>>>> Signed-off-by: Karthik B S <karthik.b.s at intel.com>
>>>> ---
>>>> drivers/gpu/drm/i915/display/intel_display.c | 10 ++++
>>>> drivers/gpu/drm/i915/i915_irq.c | 52
>>>> ++++++++++++++++++++
>>>> drivers/gpu/drm/i915/i915_irq.h | 2 +
>>>> 3 files changed, 64 insertions(+)
>>>>
>>>> diff --git a/drivers/gpu/drm/i915/display/intel_display.c
>>>> b/drivers/gpu/drm/i915/display/intel_display.c
>>>> index f40b909952cc..48cc1fc9bc5a 100644
>>>> --- a/drivers/gpu/drm/i915/display/intel_display.c
>>>> +++ b/drivers/gpu/drm/i915/display/intel_display.c
>>>> @@ -15530,6 +15530,13 @@ static void intel_atomic_commit_tail(struct
>>>> intel_atomic_state *state)
>>>>
>>>> intel_dbuf_pre_plane_update(state);
>>>>
>>>> + for_each_new_intel_crtc_in_state(state, crtc, new_crtc_state, i) {
>>>> + if (new_crtc_state->uapi.async_flip) {
>>>> + skl_enable_flip_done(&crtc->base);
>>>> + break;
>>>> + }
>>>> + }
>>>> +
>>>> /* Now enable the clocks, plane, pipe, and connectors that we
>>>> set up. */
>>>> dev_priv->display.commit_modeset_enables(state);
>>>>
>>>> @@ -15551,6 +15558,9 @@ static void intel_atomic_commit_tail(struct
>>>> intel_atomic_state *state)
>>>> drm_atomic_helper_wait_for_flip_done(dev, &state->base);
>>>>
>>>> for_each_new_intel_crtc_in_state(state, crtc, new_crtc_state, i) {
>>>> + if (new_crtc_state->uapi.async_flip)
>>>> + skl_disable_flip_done(&crtc->base);
>>>> +
>>>> if (new_crtc_state->hw.active &&
>>>> !needs_modeset(new_crtc_state) &&
>>>> !new_crtc_state->preload_luts &&
>>>> diff --git a/drivers/gpu/drm/i915/i915_irq.c
>>>> b/drivers/gpu/drm/i915/i915_irq.c
>>>> index efdd4c7b8e92..632e7b1deb87 100644
>>>> --- a/drivers/gpu/drm/i915/i915_irq.c
>>>> +++ b/drivers/gpu/drm/i915/i915_irq.c
>>>> @@ -1295,6 +1295,23 @@ display_pipe_crc_irq_handler(struct
>>>> drm_i915_private *dev_priv,
>>>> u32 crc4) {}
>>>> #endif
>>>>
>>>> +static void flip_done_handler(struct drm_i915_private *dev_priv,
>>>> + unsigned int pipe)
>>>> +{
>>>> + struct intel_crtc *crtc = intel_get_crtc_for_pipe(dev_priv, pipe);
>>>> + struct drm_crtc_state *crtc_state = crtc->base.state;
>>>> + struct drm_pending_vblank_event *e = crtc_state->event;
>>>> + struct drm_device *dev = &dev_priv->drm;
>>>> + unsigned long irqflags;
>>>> +
>>>> + crtc_state->event = NULL;
>>>> +
>>>> + spin_lock_irqsave(&dev->event_lock, irqflags);
>>>> +
>>>> + drm_crtc_send_vblank_event(&crtc->base, e);
>>>
>>> I don't think this is what we want. With this, the events the Kernel
>>> sends us all have the same sequence and timestamp. In fact, the IGT
>>> test you submitted fails because of this.
>>>
>>> In my original hackish proof-of-concept patch I had changed
>>> drm_update_vblank_count() to force diff=1 in order to always send
>>> events and I also changed g4x_get_vblank_counter() to get the counter
>>> from FLIPCOUNT (which updates every time there's a flip) instead of
>>> FRMCOUNT (which doesn't seem to increment when you do async flips).
>>> That is a drastic change, but the patch was just a PoC so I didn't care
>>> about keeping anything else working.
>>>
>>> One thing that confused me a little bit when dealing the the
>>> vblank/flip event interface from drm.ko is that "flips" and "vblanks"
>>> seem to be changed interchangeably, which is confusing for async flips:
>>> if you keep forever doing async flips in the very first few scanlines
>>> you never actually reach the "vblank" period, yet you keep flipping
>>> your frame. Then, what should your expectation regarding events be?
>>
>> Hm vblank should keep happening I thought (this isn't VRR or DRRS or PSR
>> where that changes), no idea why we can't keep sending out vblank
>> interrupts.
>>
>> Now flip events look maybe conflated in drm.ko code with vblank events
>> since most of the time a flip complete happens at exactly the same time
>> the vblank event. But for async flip this is not the case.
>>
>> Probably worth it to have new helpers/function in drm_vblank.c for
>> async flips, so that this is less confusing. Plus good documentation.
>>
>>> I think we may need to check how the other drivers handle async vblanks
>>> (or how drm.ko wants us to handle async vblanks). Should we increment
>>> sequence on every async flip? What about the timestamp?
>>>
>>> Daniel, Ville, do you happen to know the proper semantics here?
>>>
>>> There's certainly some adjustment to do to both this patch and the IGT.
>>
>> I think it would be really good if we cc dri-devel on this. amdgpu.ko is
>> currently the only implementation of async flips, we need to make sure we
>> are fully aligned on all the semantic details.
>>
>> That also means that the igt needs to be reviewed and tested by amdgpu
>> people. Might also be good to get the implementation acked by amd DC
>> people, just to make triple-sure we have the same semantics and generic
>> userspace compositors like mutter can use this across drivers. We've had
>> way too much pain here in the past, especially with the details you point
>> out here.
>>
>> Also, I think we need to have updated drm core documentation for async
>> flips, since the current ones are "do it like amdgpu does it". I think
>> just documenting the various pieces and flags in detail and how it all
>> interacts with e.g. other atomic commits and everything else would be
>> great.
>>
>> Harry and Nicholaus are the people you want from amd. Added everyone
>> to cc.
>> -Daniel
>
> IIRC async flips are treated the same as regular flips from amdgpu
> perspective. When the hardware latches the new flip address an interrupt
> is triggered and we send back the vblank event from the interrupt
> handler immediately
>
> I think we use the same timestamp calculation code for both paths in
> this case where we take the current hpos/vpos and calculate when scanout
> is going to actually occur.
>
> Technically we're actually scanning out the framebuffer immediately
> though so the timestamp is probably bogus.
>
> The regular vblank handler continues to run as usual in the background,
> there's no change to the timing. On newer hardware this triggers around
> when the hardware starts preparing the next frame, so close to the
> double buffer latch (which is typically in the back porch).
Thanks for the review.
Even in this implementation I've made the changes to send the flip done
event from the interrupt handler itself. But I've not kept the vblank
handler running in background. I'll make the appropriate changes based
on your inputs and make sure the implementation is aligned with the
amdgpu implementation for async flips.
Thanks and Regards,
Karthik.B.S
>
> Regards,
> Nicholas Kazlauskas
>
>>
>>
>>>
>>>> +
>>>> + spin_unlock_irqrestore(&dev->event_lock, irqflags);
>>>> +}
>>>>
>>>> static void hsw_pipe_crc_irq_handler(struct drm_i915_private
>>>> *dev_priv,
>>>> enum pipe pipe)
>>>> @@ -2388,6 +2405,9 @@ gen8_de_irq_handler(struct drm_i915_private
>>>> *dev_priv, u32 master_ctl)
>>>> if (iir & GEN8_PIPE_VBLANK)
>>>> intel_handle_vblank(dev_priv, pipe);
>>>>
>>>> + if (iir & GEN9_PIPE_PLANE1_FLIP_DONE)
>>>> + flip_done_handler(dev_priv, pipe);
>>>> +
>>>> if (iir & GEN8_PIPE_CDCLK_CRC_DONE)
>>>> hsw_pipe_crc_irq_handler(dev_priv, pipe);
>>>>
>>>> @@ -2669,6 +2689,19 @@ int bdw_enable_vblank(struct drm_crtc *crtc)
>>>> return 0;
>>>> }
>>>>
>>>> +void skl_enable_flip_done(struct drm_crtc *crtc)
>>>> +{
>>>> + struct drm_i915_private *dev_priv = to_i915(crtc->dev);
>>>> + enum pipe pipe = to_intel_crtc(crtc)->pipe;
>>>> + unsigned long irqflags;
>>>> +
>>>> + spin_lock_irqsave(&dev_priv->irq_lock, irqflags);
>>>> +
>>>> + bdw_enable_pipe_irq(dev_priv, pipe, GEN9_PIPE_PLANE1_FLIP_DONE);
>>>> +
>>>> + spin_unlock_irqrestore(&dev_priv->irq_lock, irqflags);
>>>> +}
>>>> +
>>>> /* Called from drm generic code, passed 'crtc' which
>>>> * we use as a pipe index
>>>> */
>>>> @@ -2729,6 +2762,19 @@ void bdw_disable_vblank(struct drm_crtc *crtc)
>>>> spin_unlock_irqrestore(&dev_priv->irq_lock, irqflags);
>>>> }
>>>>
>>>> +void skl_disable_flip_done(struct drm_crtc *crtc)
>>>> +{
>>>> + struct drm_i915_private *dev_priv = to_i915(crtc->dev);
>>>> + enum pipe pipe = to_intel_crtc(crtc)->pipe;
>>>> + unsigned long irqflags;
>>>> +
>>>> + spin_lock_irqsave(&dev_priv->irq_lock, irqflags);
>>>> +
>>>> + bdw_disable_pipe_irq(dev_priv, pipe, GEN9_PIPE_PLANE1_FLIP_DONE);
>>>> +
>>>> + spin_unlock_irqrestore(&dev_priv->irq_lock, irqflags);
>>>> +}
>>>> +
>>>> static void ibx_irq_reset(struct drm_i915_private *dev_priv)
>>>> {
>>>> struct intel_uncore *uncore = &dev_priv->uncore;
>>>> @@ -2936,6 +2982,9 @@ void gen8_irq_power_well_post_enable(struct
>>>> drm_i915_private *dev_priv,
>>>> u32 extra_ier = GEN8_PIPE_VBLANK | GEN8_PIPE_FIFO_UNDERRUN;
>>>> enum pipe pipe;
>>>>
>>>> + if (INTEL_GEN(dev_priv) >= 9)
>>>> + extra_ier |= GEN9_PIPE_PLANE1_FLIP_DONE;
>>>> +
>>>> spin_lock_irq(&dev_priv->irq_lock);
>>>>
>>>> if (!intel_irqs_enabled(dev_priv)) {
>>>> @@ -3410,6 +3459,9 @@ static void gen8_de_irq_postinstall(struct
>>>> drm_i915_private *dev_priv)
>>>> de_pipe_enables = de_pipe_masked | GEN8_PIPE_VBLANK |
>>>> GEN8_PIPE_FIFO_UNDERRUN;
>>>>
>>>> + if (INTEL_GEN(dev_priv) >= 9)
>>>> + de_pipe_enables |= GEN9_PIPE_PLANE1_FLIP_DONE;
>>>> +
>>>> de_port_enables = de_port_masked;
>>>> if (IS_GEN9_LP(dev_priv))
>>>> de_port_enables |= BXT_DE_PORT_HOTPLUG_MASK;
>>>> diff --git a/drivers/gpu/drm/i915/i915_irq.h
>>>> b/drivers/gpu/drm/i915/i915_irq.h
>>>> index 25f25cd95818..2f10c8135116 100644
>>>> --- a/drivers/gpu/drm/i915/i915_irq.h
>>>> +++ b/drivers/gpu/drm/i915/i915_irq.h
>>>> @@ -112,11 +112,13 @@ int i915gm_enable_vblank(struct drm_crtc *crtc);
>>>> int i965_enable_vblank(struct drm_crtc *crtc);
>>>> int ilk_enable_vblank(struct drm_crtc *crtc);
>>>> int bdw_enable_vblank(struct drm_crtc *crtc);
>>>> +void skl_enable_flip_done(struct drm_crtc *crtc);
>>>> void i8xx_disable_vblank(struct drm_crtc *crtc);
>>>> void i915gm_disable_vblank(struct drm_crtc *crtc);
>>>> void i965_disable_vblank(struct drm_crtc *crtc);
>>>> void ilk_disable_vblank(struct drm_crtc *crtc);
>>>> void bdw_disable_vblank(struct drm_crtc *crtc);
>>>> +void skl_disable_flip_done(struct drm_crtc *crtc);
>>>>
>>>> void gen2_irq_reset(struct intel_uncore *uncore);
>>>> void gen3_irq_reset(struct intel_uncore *uncore, i915_reg_t imr,
>>>
>>> _______________________________________________
>>> Intel-gfx mailing list
>>> Intel-gfx at lists.freedesktop.org
>>> https://lists.freedesktop.org/mailman/listinfo/intel-gfx
>>
>> --
>> Daniel Vetter
>> Software Engineer, Intel Corporation
>> http://blog.ffwll.ch/
>>
>
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