[PATCH 2/2] drm/i915: Implement vblank synchronized MBUS join changes
Ville Syrjälä
ville.syrjala at linux.intel.com
Fri Mar 15 16:52:40 UTC 2024
On Fri, Mar 15, 2024 at 06:48:56PM +0200, Ville Syrjälä wrote:
> On Fri, Mar 15, 2024 at 01:34:07PM +0200, Stanislav Lisovskiy wrote:
> > Currently we can't change MBUS join status without doing a modeset,
> > because we are lacking mechanism to synchronize those with vblank.
> > However then this means that we can't do a fastset, if there is a need
> > to change MBUS join state. Fix that by implementing such change.
> > We already call correspondent check and update at pre_plane dbuf update,
> > so the only thing left is to have a non-modeset version of that.
> > If active pipes stay the same then fastset is possible and only MBUS
> > join state/ddb allocation updates would be committed.
> >
> > v2: Implement additional changes according to BSpec.
> > Vblank wait is needed after MBus/Dbuf programming in case if
> > no modeset is done and we are switching from single to multiple
> > displays, i.e mbus join state switches from "joined" to "non-joined"
> > state. Otherwise vblank wait is not needed according to spec.
> >
> > v3: Split mbus and dbox programming into to pre/post plane update parts,
> > how it should be done according to BSpec.
> >
> > v4: - Place "single display to multiple displays scenario" MBUS/DBOX programming
> > after DDB reallocation, but before crtc enabling(that is where is has
> > to be according to spec).
> > - Check if crtc is still active, not only the old state.
> > - Do a vblank wait if MBUX DBOX register was modified.
> > - And of course do vblank wait only if crtc was active.
> > - Do vblank wait only if we are not doing a modeset, if we are doing
> > something before *commit_modeset_enables, because all crtcs might be
> > disabled at this moment, so we will get WARN if try waiting for vblank
> > then.
> > - Still getting FIFO underrun so try waiting for vblank in pre_plane update
> > as well.
> > - Write also pipe that we need to sync with to MBUS_CTL register.
> >
> > v5: - Do vblank wait only for the first pipe, if mbus is joined
> > - Check also if new/old_dbuf_state is not NULL, before getting single pipe
> > and active pipes.
> >
> > v6: - Add pre/post ddb call sites for doing mbus/mbox updates for switching
> > between single/multiple displays(Ville Syrjälä)
> > - When writing MBUS_CTL check if synced pipe is enabled, otherwise use
> > PIPE_NONE sync option(Ville Syrjälä)
> > - Use for_each_crtc_in_pipe_mask to go through all active pipes, not
> > just ones in state, when updating mbox registers(Ville Syrjälä)
> > - Improve checks for switching between multiple <=> single displays
> >
> > Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy at intel.com>
> > ---
> > drivers/gpu/drm/i915/display/intel_display.c | 15 ++-
> > drivers/gpu/drm/i915/display/skl_watermark.c | 113 +++++++++++++++----
> > drivers/gpu/drm/i915/display/skl_watermark.h | 2 +
> > 3 files changed, 105 insertions(+), 25 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
> > index b88f214e111ae..6e4b2c941b63e 100644
> > --- a/drivers/gpu/drm/i915/display/intel_display.c
> > +++ b/drivers/gpu/drm/i915/display/intel_display.c
> > @@ -6895,6 +6895,8 @@ static void skl_commit_modeset_enables(struct intel_atomic_state *state)
> > intel_pre_update_crtc(state, crtc);
> > }
> >
> > + intel_dbuf_mbus_pre_ddb_update(state);
> > +
> > while (update_pipes) {
> > for_each_oldnew_intel_crtc_in_state(state, crtc, old_crtc_state,
> > new_crtc_state, i) {
> > @@ -6925,6 +6927,17 @@ static void skl_commit_modeset_enables(struct intel_atomic_state *state)
> > }
> > }
> >
> > + /*
> > + * Some MBUS/DBuf update scenarios(mbus join disable) require that
> > + * changes are done _after_ DDB reallocation, but _before_ crtc enabling.
> > + * Typically we are disabling resources in post_plane/crtc_enable hooks,
> > + * however in that case BSpec explicitly states that this should be done
> > + * before we enable additional displays.
> > + * FIXME: Should we still call this also there(post_plane hook)
> > + * for extra-safety? If so, how to make sure, we don't call it twice?
> > + */
> > + intel_dbuf_mbus_post_ddb_update(state);
> > +
> > update_pipes = modeset_pipes;
> >
> > /*
> > @@ -7169,9 +7182,7 @@ static void intel_atomic_commit_tail(struct intel_atomic_state *state)
> > }
> >
> > intel_encoders_update_prepare(state);
> > -
> > intel_dbuf_pre_plane_update(state);
> > - intel_mbus_dbox_update(state);
> >
> > for_each_new_intel_crtc_in_state(state, crtc, new_crtc_state, i) {
> > if (new_crtc_state->do_async_flip)
> > diff --git a/drivers/gpu/drm/i915/display/skl_watermark.c b/drivers/gpu/drm/i915/display/skl_watermark.c
> > index 2d3b08c2f8d78..4c8313154d88c 100644
> > --- a/drivers/gpu/drm/i915/display/skl_watermark.c
> > +++ b/drivers/gpu/drm/i915/display/skl_watermark.c
> > @@ -2636,13 +2636,6 @@ skl_compute_ddb(struct intel_atomic_state *state)
> > if (ret)
> > return ret;
> >
> > - if (old_dbuf_state->joined_mbus != new_dbuf_state->joined_mbus) {
> > - /* TODO: Implement vblank synchronized MBUS joining changes */
> > - ret = intel_modeset_all_pipes_late(state, "MBUS joining change");
> > - if (ret)
> > - return ret;
> > - }
> > -
> > drm_dbg_kms(&i915->drm,
> > "Enabled dbuf slices 0x%x -> 0x%x (total dbuf slices 0x%x), mbus joined? %s->%s\n",
> > old_dbuf_state->enabled_slices,
> > @@ -3582,20 +3575,31 @@ static void intel_dbuf_mbus_update(struct intel_atomic_state *state)
> > intel_atomic_get_old_dbuf_state(state);
> > const struct intel_dbuf_state *new_dbuf_state =
> > intel_atomic_get_new_dbuf_state(state);
> > + u32 pipe_select = MBUS_JOIN_PIPE_SELECT_NONE;
> >
> > if (!HAS_MBUS_JOINING(i915))
> > return;
> >
> > + if (new_dbuf_state->active_pipes) {
> > + enum pipe sync_pipe = ffs(new_dbuf_state->active_pipes) - 1;
> > + struct intel_crtc *crtc = intel_crtc_for_pipe(i915, sync_pipe);
> > + struct intel_crtc_state *new_crtc_state =
> > + intel_atomic_get_new_crtc_state(state, crtc);
> > +
> > + if (new_crtc_state && !intel_crtc_needs_modeset(new_crtc_state))
> > + pipe_select = MBUS_JOIN_PIPE_SELECT(sync_pipe);
> > + }
>
> That looks like a function.
>
> > +
> > /*
> > * TODO: Implement vblank synchronized MBUS joining changes.
> > * Must be properly coordinated with dbuf reprogramming.
> > */
> > if (new_dbuf_state->joined_mbus)
> > mbus_ctl = MBUS_HASHING_MODE_1x4 | MBUS_JOIN |
> > - MBUS_JOIN_PIPE_SELECT_NONE;
> > + pipe_select;
> > else
> > mbus_ctl = MBUS_HASHING_MODE_2x2 |
> > - MBUS_JOIN_PIPE_SELECT_NONE;
> > + pipe_select;
> >
> > intel_de_rmw(i915, MBUS_CTL,
> > MBUS_HASHING_MODE_MASK | MBUS_JOIN |
> > @@ -3632,10 +3636,6 @@ void intel_dbuf_pre_plane_update(struct intel_atomic_state *state)
> >
> > WARN_ON(!new_dbuf_state->base.changed);
> >
> > - if ((hweight8(new_dbuf_state->active_pipes) <= hweight8(old_dbuf_state->active_pipes))
> > - || (old_dbuf_state->active_pipes == 0))
> > - intel_dbuf_mbus_update(state);
> > -
> > gen9_dbuf_slices_update(i915,
> > old_dbuf_state->enabled_slices |
> > new_dbuf_state->enabled_slices);
> > @@ -3656,13 +3656,85 @@ void intel_dbuf_post_plane_update(struct intel_atomic_state *state)
> >
> > WARN_ON(!new_dbuf_state->base.changed);
> >
> > - if (hweight8(new_dbuf_state->active_pipes) > hweight8(old_dbuf_state->active_pipes))
> > - intel_dbuf_mbus_update(state);
> > -
> > gen9_dbuf_slices_update(i915,
> > new_dbuf_state->enabled_slices);
> > }
> >
> > +void intel_dbuf_mbus_pre_ddb_update(struct intel_atomic_state *state)
> > +{
> > + const struct intel_dbuf_state *new_dbuf_state =
> > + intel_atomic_get_new_dbuf_state(state);
> > + const struct intel_dbuf_state *old_dbuf_state =
> > + intel_atomic_get_old_dbuf_state(state);
> > + int new_num_active_pipes;
> > +
> > + if (!new_dbuf_state ||
> > + (new_dbuf_state->enabled_slices == old_dbuf_state->enabled_slices &&
> > + new_dbuf_state->joined_mbus == old_dbuf_state->joined_mbus))
> > + return;
> > +
> > + new_num_active_pipes = hweight8(new_dbuf_state->active_pipes);
> > +
> > + WARN_ON(!new_dbuf_state->base.changed);
> > +
> > + /*
> > + * Switching to single display scenario(enable mbus join).
> > + */
> > + if (new_num_active_pipes == 1 &&
>
> I don't think we need any num_active_pipes check here. All we really
> care about is mbus joining getting enabled.
>
> > + new_dbuf_state->joined_mbus != old_dbuf_state->joined_mbus) {
> > + intel_dbuf_mbus_update(state);
> > + intel_mbus_dbox_update(state);
> > + }
> > +}
> > +
> > +void intel_dbuf_mbus_post_ddb_update(struct intel_atomic_state *state)
> > +{
> > + const struct intel_dbuf_state *new_dbuf_state =
> > + intel_atomic_get_new_dbuf_state(state);
> > + const struct intel_dbuf_state *old_dbuf_state =
> > + intel_atomic_get_old_dbuf_state(state);
> > + int new_num_active_pipes;
> > +
> > + if (!new_dbuf_state ||
> > + (new_dbuf_state->enabled_slices == old_dbuf_state->enabled_slices &&
> > + new_dbuf_state->joined_mbus == old_dbuf_state->joined_mbus))
> > + return;
> > +
> > + new_num_active_pipes = hweight8(new_dbuf_state->active_pipes);
> > +
> > + WARN_ON(!new_dbuf_state->base.changed);
> > +
> > + /*
> > + * Switching to multiple display scenario
> > + */
> > + if (new_num_active_pipes > 1 &&
>
> Again I don't think we need that check.
>
> > + new_dbuf_state->joined_mbus != old_dbuf_state->joined_mbus) {
>
> This is one case we need to handle.
Actually that should be
'!new_dbuf_state->mbus_join && old_dbuf_state->mbus_join'
Though personally I would write those in the opposite
order since then the reading order matches the chronological
order and thus is easier to understand (at least for me).
>
> > + struct intel_crtc *crtc;
> > + struct intel_crtc_state *new_crtc_state;
> > + enum pipe pipe;
> > + int i;
> > +
> > + pipe = ffs(new_dbuf_state->active_pipes) - 1;
>
> This should use the same function to determine the correct pipe for the
> mbus update. The difference is here we want to use the
> old_dbuf_state->active_pipes as that is what indicates which pipes was
> using the joined mbus previously.
>
> > +
> > + intel_dbuf_mbus_update(state);
> > + intel_mbus_dbox_update(state);
> > +
> > + for_each_new_intel_crtc_in_state(state, crtc, new_crtc_state, i) {
> > + /*
> > + * According to BSpec we should wait vblank on single display,
> > + * before enabling additional displays
> > + */
> > + if (!new_crtc_state->hw.active || (crtc->pipe != pipe))
> > + continue;
> > +
> > + if (intel_crtc_needs_modeset(new_crtc_state))
> > + continue;
> > +
> > + intel_crtc_wait_for_next_vblank(crtc);
> > + }
>
> No need to loop over the crtcs in the state here. You already know the
> pipe so just do a vblank wait on it.
>
> > + }
>
> The other case we need to handle is when mbus joining doesn't change.
> In which case we still need to do the dbuf_min_tracker and dbox stuff.
> But there we don't need to care about the MBUS_CTL pipe stuff.
>
> > +}
> > +
> > static bool xelpdp_is_only_pipe_per_dbuf_bank(enum pipe pipe, u8 active_pipes)
> > {
> > switch (pipe) {
> > @@ -3686,10 +3758,8 @@ void intel_mbus_dbox_update(struct intel_atomic_state *state)
> > {
> > struct drm_i915_private *i915 = to_i915(state->base.dev);
> > const struct intel_dbuf_state *new_dbuf_state, *old_dbuf_state;
> > - const struct intel_crtc_state *new_crtc_state;
> > - const struct intel_crtc *crtc;
> > + struct intel_crtc *crtc;
> > u32 val = 0;
> > - int i;
> >
> > if (DISPLAY_VER(i915) < 11)
> > return;
> > @@ -3733,12 +3803,9 @@ void intel_mbus_dbox_update(struct intel_atomic_state *state)
> > val |= MBUS_DBOX_B_CREDIT(8);
> > }
> >
> > - for_each_new_intel_crtc_in_state(state, crtc, new_crtc_state, i) {
> > + for_each_intel_crtc_in_pipe_mask(&i915->drm, crtc, new_dbuf_state->active_pipes) {
> > u32 pipe_val = val;
> >
> > - if (!new_crtc_state->hw.active)
> > - continue;
> > -
>
> This stuff should be a separate patch.
>
> > if (DISPLAY_VER(i915) >= 14) {
> > if (xelpdp_is_only_pipe_per_dbuf_bank(crtc->pipe,
> > new_dbuf_state->active_pipes))
> > diff --git a/drivers/gpu/drm/i915/display/skl_watermark.h b/drivers/gpu/drm/i915/display/skl_watermark.h
> > index 3a90741cab06a..f6d38b41e3a6c 100644
> > --- a/drivers/gpu/drm/i915/display/skl_watermark.h
> > +++ b/drivers/gpu/drm/i915/display/skl_watermark.h
> > @@ -77,6 +77,8 @@ int intel_dbuf_state_set_mdclk_cdclk_ratio(struct intel_atomic_state *state, u8
> > void intel_dbuf_pre_plane_update(struct intel_atomic_state *state);
> > void intel_dbuf_post_plane_update(struct intel_atomic_state *state);
> > void intel_dbuf_mdclk_cdclk_ratio_update(struct drm_i915_private *i915, u8 ratio, bool joined_mbus);
> > +void intel_dbuf_mbus_pre_ddb_update(struct intel_atomic_state *state);
> > +void intel_dbuf_mbus_post_ddb_update(struct intel_atomic_state *state);
> > void intel_mbus_dbox_update(struct intel_atomic_state *state);
> >
> > #endif /* __SKL_WATERMARK_H__ */
> > --
> > 2.37.3
>
> --
> Ville Syrjälä
> Intel
--
Ville Syrjälä
Intel
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