[Intel-gfx] [PATCH v6 8/8] drm/i915/gen9: WM memory bandwidth related workaround
Lankhorst, Maarten
maarten.lankhorst at intel.com
Tue Nov 29 09:46:11 UTC 2016
Mahesh Kumar schreef op di 29-11-2016 om 11:12 [+0530]:
> Hi,
>
>
> On Thursday 24 November 2016 06:21 PM, Lankhorst, Maarten wrote:
> >
> > Mahesh Kumar schreef op do 24-11-2016 om 09:31 [+0530]:
> > >
> > > This patch implemnets Workariunds related to display arbitrated
> > > memory
> > > bandwidth. These WA are applicabe for all gen-9 based platforms.
> > >
> > > Changes since v1:
> > > - Rebase on top of Paulo's patch series
> > > Changes since v2:
> > > - Address review comments
> > > - Rebase/rework as per other patch changes in series
> > >
> > > Signed-off-by: Mahesh Kumar <mahesh1.kumar at intel.com>
> > > ---
> > > drivers/gpu/drm/i915/i915_drv.h | 9 +++
> > > drivers/gpu/drm/i915/intel_pm.c | 149
> > > +++++++++++++++++++++++++++++++++++++---
> > > 2 files changed, 149 insertions(+), 9 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/i915/i915_drv.h
> > > b/drivers/gpu/drm/i915/i915_drv.h
> > > index 4e2f17f..2b673c6 100644
> > > --- a/drivers/gpu/drm/i915/i915_drv.h
> > > +++ b/drivers/gpu/drm/i915/i915_drv.h
> > > @@ -1193,6 +1193,13 @@ enum intel_sbi_destination {
> > > SBI_MPHY,
> > > };
> > >
> > > +/* SKL+ Watermark arbitrated display bandwidth Workarounds */
> > > +enum watermark_memory_wa {
> > > + WATERMARK_WA_NONE,
> > > + WATERMARK_WA_X_TILED,
> > > + WATERMARK_WA_Y_TILED,
> > > +};
> > > +
> > > #define QUIRK_PIPEA_FORCE (1<<0)
> > > #define QUIRK_LVDS_SSC_DISABLE (1<<1)
> > > #define QUIRK_INVERT_BRIGHTNESS (1<<2)
> > > @@ -1764,6 +1771,8 @@ struct skl_ddb_allocation {
> > >
> > > struct skl_wm_values {
> > > unsigned dirty_pipes;
> > > + /* any WaterMark memory workaround Required */
> > > + enum watermark_memory_wa mem_wa;
> > > struct skl_ddb_allocation ddb;
> > > };
> > >
> > > diff --git a/drivers/gpu/drm/i915/intel_pm.c
> > > b/drivers/gpu/drm/i915/intel_pm.c
> > > index 3e2dd8f..547bbda 100644
> > > --- a/drivers/gpu/drm/i915/intel_pm.c
> > > +++ b/drivers/gpu/drm/i915/intel_pm.c
> > > @@ -2889,11 +2889,7 @@ skl_wm_plane_id(const struct intel_plane
> > > *plane)
> > > }
> > > }
> > >
> > > -/*
> > > - * FIXME: We still don't have the proper code detect if we need
> > > to
> > > apply the WA,
> > > - * so assume we'll always need it in order to avoid underruns.
> > > - */
> > > -static bool skl_needs_memory_bw_wa(struct intel_atomic_state
> > > *state)
> > > +static bool intel_needs_memory_bw_wa(struct intel_atomic_state
> > > *state)
> > > {
> > > struct drm_i915_private *dev_priv = to_i915(state-
> > > >
> > > > base.dev);
> > >
> > > @@ -3067,7 +3063,7 @@ bool intel_can_enable_sagv(struct
> > > drm_atomic_state *state)
> > >
> > > latency = dev_priv->wm.skl_latency[level];
> > >
> > > - if (skl_needs_memory_bw_wa(intel_state) &&
> > > + if (intel_needs_memory_bw_wa(intel_state) &&
> > > plane->base.state->fb->modifier ==
> > > I915_FORMAT_MOD_X_TILED)
> > > latency += 15;
> > > @@ -3597,7 +3593,7 @@ static int skl_compute_plane_wm(const
> > > struct
> > > drm_i915_private *dev_priv,
> > > uint32_t y_min_scanlines;
> > > struct intel_atomic_state *state =
> > > to_intel_atomic_state(cstate->base.state);
> > > - bool apply_memory_bw_wa = skl_needs_memory_bw_wa(state);
> > > + enum watermark_memory_wa mem_wa;
> > > bool y_tiled, x_tiled;
> > >
> > > if (latency == 0 || !cstate->base.active ||
> > > !intel_pstate-
> > > >
> > > > base.visible) {
> > > @@ -3613,7 +3609,8 @@ static int skl_compute_plane_wm(const
> > > struct
> > > drm_i915_private *dev_priv,
> > > if (IS_KABYLAKE(dev_priv) && dev_priv->ipc_enabled)
> > > latency += 4;
> > >
> > > - if (apply_memory_bw_wa && x_tiled)
> > > + mem_wa = state->wm_results.mem_wa;
> > > + if (mem_wa != WATERMARK_WA_NONE && x_tiled)
> > > latency += 15;
> > >
> > > width = drm_rect_width(&intel_pstate->base.src) >> 16;
> > > @@ -3648,7 +3645,7 @@ static int skl_compute_plane_wm(const
> > > struct
> > > drm_i915_private *dev_priv,
> > > y_min_scanlines = 4;
> > > }
> > >
> > > - if (apply_memory_bw_wa)
> > > + if (mem_wa == WATERMARK_WA_Y_TILED)
> > > y_min_scanlines *= 2;
> > >
> > > plane_bytes_per_line = width * cpp;
> > > @@ -4077,6 +4074,15 @@ skl_compute_ddb(struct drm_atomic_state
> > > *state)
> > > }
> > >
> > > /*
> > > + * If Watermark workaround is changed we need to
> > > recalculate
> > > + * watermark values for all active pipes
> > > + */
> > > + if (intel_state->wm_results.mem_wa != dev_priv-
> > > >
> > > > wm.skl_hw.mem_wa) {
> > > + realloc_pipes = ~0;
> > > + intel_state->wm_results.dirty_pipes = ~0;
> > > + }
> > > +
> > > + /*
> > > * We're not recomputing for the pipes not included in
> > > the
> > > commit, so
> > > * make sure we start with the current state.
> > > */
> > > @@ -4102,6 +4108,129 @@ skl_compute_ddb(struct drm_atomic_state
> > > *state)
> > > }
> > >
> > > static void
> > > +skl_compute_memory_bandwidth_wm_wa(struct drm_atomic_state
> > > *state)
> > > +{
> > > + struct drm_device *dev = state->dev;
> > > + struct drm_i915_private *dev_priv = to_i915(dev);
> > > + struct intel_crtc *intel_crtc;
> > > + struct intel_plane_state *intel_pstate;
> > > + struct intel_atomic_state *intel_state =
> > > to_intel_atomic_state(state);
> > > + struct memdev_info *memdev_info = &dev_priv-
> > > >memdev_info;
> > > + int num_active_pipes;
> > > + uint32_t max_pipe_bw_kbps, total_pipe_bw_kbps;
> > > + int display_bw_percentage;
> > > + bool y_tile_enabled = false;
> > > +
> > > + if (!intel_needs_memory_bw_wa(intel_state)) {
> > > + intel_state->wm_results.mem_wa =
> > > WATERMARK_WA_NONE;
> > > + return;
> > > + }
> > > +
> > > + if (!memdev_info->valid)
> > > + goto exit;
> > > +
> > > + max_pipe_bw_kbps = 0;
> > > + num_active_pipes = 0;
> > > + for_each_intel_crtc(dev, intel_crtc) {
> > > + struct intel_crtc_state *cstate;
> > > + struct intel_plane *plane;
> > > + int num_active_planes;
> > > + uint32_t max_plane_bw_kbps, pipe_bw_kbps;
> > > +
> > > + /*
> > > + * If CRTC is part of current atomic commit, get
> > > crtc state from
> > > + * existing CRTC state. else take the cached
> > > CRTC
> > > state
> > > + */
> > > + cstate = NULL;
> > > + if (state)
> > > + cstate =
> > > intel_atomic_get_existing_crtc_state(state,
> > > + intel_crtc);
> > > + if (!cstate)
> > > + cstate = to_intel_crtc_state(intel_crtc-
> > > >
> > > > base.state);
> > This is really really not allowed. If you want to access
> > crtc->state, you need to get the state.
> >
> > Since a w/a forces a full recalculation, best you can do is put the
> > per
> > pipe status in crtc_state->wm.skl as well. If it changes you could
> > add
> > all other pipes.
> I really don't want to add all pipes in "state" until that is
> necessary
> otherwise it'll make our commit huge, that's why getting the cached
> state.
> Same goes for plane. Later if w/a changes then I'm adding all the
> CRTC's in relloc_pipes mask.
>
> if (intel_state->wm_results.mem_wa != dev_priv-
> >wm.skl_hw.mem_wa)
>
> If I hold the crtc->mutex or plane->mutex lock, It may cause
> deadlock
> with other commits.
> I can keep a cached copy of plane memory bandwidth requirement in
> "dev_priv->wm.skl_hw", but again if there are two parallel commits
> it
> may cause race.
>
> Can you please suggest what is the correct way of getting plane/crtc
> state during check phase without have to actually commit them (add
> in
> global-state),
> If any such thing is available in atomic framework?
How often will the workaround status change in practice?
You could do same as active_crtcs, protect changing the workaround
current crtc's workaround mode in dev_priv->wm.skl.wa_state[pipe] with
connection_mutex. If this means changing that the global workaround
setting is changed, then also acquire all other crtc states.
I can't say it's pretty though, it would need a good justification for
how bad the problem is in practice plus pretty good documentation on
why it works.
~Maarten
---------------------------------------------------------------------
Intel International B.V.
Registered in The Netherlands under number 34098535
Statutory seat: Haarlemmermeer
Registered address: Capronilaan 37, 1119NG Schiphol-Rijk
This e-mail and any attachments may contain confidential material for
the sole use of the intended recipient(s). Any review or distribution
by others is strictly prohibited. If you are not the intended
recipient, please contact the sender and delete all copies.
More information about the Intel-gfx
mailing list