[Intel-gfx] [PATCH v2 2/3] drm/i915: Adjust CDCLK accordingly to our DBuf bw needs
Lisovskiy, Stanislav
stanislav.lisovskiy at intel.com
Tue Mar 17 14:40:38 UTC 2020
>Something like?
>for_each_plane_id() {
> for_each_dbuf_slice() {
> skl_ddb_entry_for_slices(BIT(slice), &ddb_slice);
>
> if (skl_ddb_entries_overlap(&ddb_slice, &ddb[plane_id])))
> bw[slice] += data_rate;
> }
>}
In fact even in your example this is not fully correct:
it should be then
for_each_new_crtc_in_state() => because there are multiple crtcs
for_each_plane_id() {
for_each_dbuf_slice() {
skl_ddb_entry_for_slices(BIT(slice), &ddb_slice);
if (skl_ddb_entries_overlap(&ddb_slice, &ddb[plane_id])))
bw[slice] += data_rate;
}
}
which would be in fact same complexity or even worse because in the patch
we get a mask of only used slices per plane ddb and then account for those
while here it would be iterating all slices everytime.
Slight difference but still.
I can of course make this function shorter, by implementing some helpers -
that's for sure.
>But this seems to borked anyway since we only consider the crtcs in the
>state, and there are those ugly FIXMEs below.
Those ugly FIXME's are there because of same issue that we don't
have a parent state for crtc_state in some situations.
Not this patch fault or subject in fact. We probably need some series
to somehow tackle this everywhere, so that those functions which
need intel_atomic_state can always find it.
So it is not those FIXME's in the patch which are ugly, but the code
which is calling this function, so that even though we have a crtc_state
we never now if we can have a parent atomic state, which is violating
OOP principles.
I.e it is called from intel_modeset_setup_hw_state _already_ in a hacky way.
>I have a feeling what we want is dbuf_state, and track the bw used for
>each slice therein. Should also allow us to flag the cdclk recalculation
>only when things actually change in a way that needs more cdclk, instead
>of pessimising every plane enable/disable like you do below.
I think CDCLK recalculation itself is pretty trivial - it is actually when we really
needs to be changed, that is what we don't want to often, right?
To estimate if it needs to be flagged or not you will need exatly same code, i.e
calculating BW used per slice, while determining which ddb entries are related
to which slice.
In fact there are already IGT results(which pass) and CDCLK doesn't change too
often at all - because we change it only when we really need it otherwise
intel_crtc_compute_min_cdclk will return same value as before and nothing changes.
If you really want so, we can start tracking it, once your dbuf_state patches land - currently
the main problem is that we need finally a proper way to estimate CDCLK
without keeping it bumped all the time to make 8K happy, at the same time
we don't want FIFO underruns again.
Best Regards,
Lisovskiy Stanislav
________________________________
From: Ville Syrjälä <ville.syrjala at linux.intel.com>
Sent: Tuesday, March 17, 2020 3:46:35 PM
To: Lisovskiy, Stanislav
Cc: intel-gfx at lists.freedesktop.org; Ausmus, James; Saarinen, Jani; Roper, Matthew D
Subject: Re: [PATCH v2 2/3] drm/i915: Adjust CDCLK accordingly to our DBuf bw needs
On Tue, Mar 17, 2020 at 12:43:38AM +0200, Stanislav Lisovskiy wrote:
> According to BSpec max BW per slice is calculated using formula
> Max BW = CDCLK * 64. Currently when calculating min CDCLK we
> account only per plane requirements, however in order to avoid
> FIFO underruns we need to estimate accumulated BW consumed by
> all planes(ddb entries basically) residing on that particular
> DBuf slice. This will allow us to put CDCLK lower and save power
> when we don't need that much bandwidth or gain additional
> performance once plane consumption grows.
>
> v2: - Fix long line warning
> - Limited new DBuf bw checks to only gens >= 11
>
> Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy at intel.com>
> ---
> drivers/gpu/drm/i915/display/intel_bw.c | 46 +++++++++++++++++++
> drivers/gpu/drm/i915/display/intel_bw.h | 1 +
> drivers/gpu/drm/i915/display/intel_cdclk.c | 25 ++++++++++
> drivers/gpu/drm/i915/display/intel_display.c | 10 +++-
> .../drm/i915/display/intel_display_power.h | 1 +
> drivers/gpu/drm/i915/intel_pm.c | 34 +++++++++++++-
> drivers/gpu/drm/i915/intel_pm.h | 3 ++
> 7 files changed, 117 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_bw.c b/drivers/gpu/drm/i915/display/intel_bw.c
> index 58b264bc318d..a85125110d7e 100644
> --- a/drivers/gpu/drm/i915/display/intel_bw.c
> +++ b/drivers/gpu/drm/i915/display/intel_bw.c
> @@ -6,6 +6,7 @@
> #include <drm/drm_atomic_state_helper.h>
>
> #include "intel_bw.h"
> +#include "intel_pm.h"
> #include "intel_display_types.h"
> #include "intel_sideband.h"
>
> @@ -334,6 +335,51 @@ static unsigned int intel_bw_crtc_data_rate(const struct intel_crtc_state *crtc_
> return data_rate;
> }
>
> +int intel_bw_calc_min_cdclk(struct intel_atomic_state *state)
> +{
> + struct drm_i915_private *dev_priv = to_i915(state->base.dev);
> + int max_bw_per_dbuf[DBUF_SLICE_MAX];
> + int i = 0;
> + enum plane_id plane_id;
> + struct intel_crtc_state *crtc_state;
> + struct intel_crtc *crtc;
> + int max_bw = 0;
> + int min_cdclk;
> +
> + memset(max_bw_per_dbuf, 0, sizeof(max_bw_per_dbuf[0]) * DBUF_SLICE_MAX);
> +
> + for_each_new_intel_crtc_in_state(state, crtc, crtc_state, i) {
> + for_each_plane_id_on_crtc(crtc, plane_id) {
> + struct skl_ddb_entry *plane_alloc =
> + &crtc_state->wm.skl.plane_ddb_y[plane_id];
> + struct skl_ddb_entry *uv_plane_alloc =
> + &crtc_state->wm.skl.plane_ddb_uv[plane_id];
> + unsigned int data_rate = crtc_state->data_rate[plane_id];
> + int slice_id = 0;
> + u32 dbuf_mask = skl_ddb_dbuf_slice_mask(dev_priv, plane_alloc);
> +
> + dbuf_mask |= skl_ddb_dbuf_slice_mask(dev_priv, uv_plane_alloc);
> +
> + DRM_DEBUG_KMS("Got dbuf mask %x for pipe %c ddb %d-%d plane %d data rate %d\n",
> + dbuf_mask, pipe_name(crtc->pipe), plane_alloc->start,
> + plane_alloc->end, plane_id, data_rate);
> +
> + while (dbuf_mask != 0) {
> + if (dbuf_mask & 1) {
> + max_bw_per_dbuf[slice_id] += data_rate;
> + max_bw = max(max_bw, max_bw_per_dbuf[slice_id]);
> + }
> + slice_id++;
> + dbuf_mask >>= 1;
> + }
> + }
> + }
Something like?
for_each_plane_id() {
for_each_dbuf_slice() {
skl_ddb_entry_for_slices(BIT(slice), &ddb_slice);
if (skl_ddb_entries_overlap(&ddb_slice, &ddb[plane_id])))
bw[slice] += data_rate;
}
}
But this seems to borked anyway since we only consider the crtcs in the
state, and there are those ugly FIXMEs below.
I have a feeling what we want is dbuf_state, and track the bw used for
each slice therein. Should also allow us to flag the cdclk recalculation
only when things actually change in a way that needs more cdclk, instead
of pessimising every plane enable/disable like you do below.
> +
> + min_cdclk = max_bw / 64;
> +
> + return min_cdclk;
> +}
> +
> void intel_bw_crtc_update(struct intel_bw_state *bw_state,
> const struct intel_crtc_state *crtc_state)
> {
> diff --git a/drivers/gpu/drm/i915/display/intel_bw.h b/drivers/gpu/drm/i915/display/intel_bw.h
> index a8aa7624c5aa..8a522b571c51 100644
> --- a/drivers/gpu/drm/i915/display/intel_bw.h
> +++ b/drivers/gpu/drm/i915/display/intel_bw.h
> @@ -29,5 +29,6 @@ int intel_bw_init(struct drm_i915_private *dev_priv);
> int intel_bw_atomic_check(struct intel_atomic_state *state);
> void intel_bw_crtc_update(struct intel_bw_state *bw_state,
> const struct intel_crtc_state *crtc_state);
> +int intel_bw_calc_min_cdclk(struct intel_atomic_state *state);
>
> #endif /* __INTEL_BW_H__ */
> diff --git a/drivers/gpu/drm/i915/display/intel_cdclk.c b/drivers/gpu/drm/i915/display/intel_cdclk.c
> index 0741d643455b..9f2de613642e 100644
> --- a/drivers/gpu/drm/i915/display/intel_cdclk.c
> +++ b/drivers/gpu/drm/i915/display/intel_cdclk.c
> @@ -25,6 +25,7 @@
> #include "intel_cdclk.h"
> #include "intel_display_types.h"
> #include "intel_sideband.h"
> +#include "intel_bw.h"
>
> /**
> * DOC: CDCLK / RAWCLK
> @@ -1979,11 +1980,19 @@ int intel_crtc_compute_min_cdclk(const struct intel_crtc_state *crtc_state)
> {
> struct drm_i915_private *dev_priv =
> to_i915(crtc_state->uapi.crtc->dev);
> + struct intel_atomic_state *state = NULL;
> int min_cdclk;
>
> if (!crtc_state->hw.enable)
> return 0;
>
> + /*
> + * FIXME: Unfortunately when this gets called from intel_modeset_setup_hw_state
> + * there is no intel_atomic_state at all. So lets not then use it.
> + */
> + if (crtc_state->uapi.state)
> + state = to_intel_atomic_state(crtc_state->uapi.state);
> +
> min_cdclk = intel_pixel_rate_to_cdclk(crtc_state);
>
> /* pixel rate mustn't exceed 95% of cdclk with IPS on BDW */
> @@ -2058,6 +2067,22 @@ int intel_crtc_compute_min_cdclk(const struct intel_crtc_state *crtc_state)
> if (IS_TIGERLAKE(dev_priv))
> min_cdclk = max(min_cdclk, (int)crtc_state->pixel_rate);
>
> + /*
> + * Similar story as with skl_write_plane_wm and intel_enable_sagv
> + * - in some certain driver parts, we don't have any guarantee that
> + * parent exists. So we might be having a crtc_state without
> + * parent state.
> + */
> + if (INTEL_GEN(dev_priv) >= 11) {
> + if (state) {
> + int dbuf_bw_cdclk = intel_bw_calc_min_cdclk(state);
> +
> + DRM_DEBUG_KMS("DBuf bw min cdclk %d current min_cdclk %d\n",
> + dbuf_bw_cdclk, min_cdclk);
> + min_cdclk = max(min_cdclk, dbuf_bw_cdclk);
> + }
> + }
> +
> if (min_cdclk > dev_priv->max_cdclk_freq) {
> drm_dbg_kms(&dev_priv->drm,
> "required cdclk (%d kHz) exceeds max (%d kHz)\n",
> diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
> index cdff3054b344..aae5521424c6 100644
> --- a/drivers/gpu/drm/i915/display/intel_display.c
> +++ b/drivers/gpu/drm/i915/display/intel_display.c
> @@ -14632,7 +14632,7 @@ static bool active_planes_affects_min_cdclk(struct drm_i915_private *dev_priv)
> /* See {hsw,vlv,ivb}_plane_ratio() */
> return IS_BROADWELL(dev_priv) || IS_HASWELL(dev_priv) ||
> IS_CHERRYVIEW(dev_priv) || IS_VALLEYVIEW(dev_priv) ||
> - IS_IVYBRIDGE(dev_priv);
> + IS_IVYBRIDGE(dev_priv) || (INTEL_GEN(dev_priv) >= 11);
> }
>
> static int intel_atomic_check_planes(struct intel_atomic_state *state,
> @@ -14681,6 +14681,14 @@ static int intel_atomic_check_planes(struct intel_atomic_state *state,
> if (hweight8(old_active_planes) == hweight8(new_active_planes))
> continue;
>
> + /*
> + * active_planes bitmask has been updated, whenever amount
> + * of active planes had changed we need to recalculate CDCLK
> + * as it depends on total bandwidth now, not only min_cdclk
> + * per plane.
> + */
> + *need_cdclk_calc = true;
> +
> ret = intel_crtc_add_planes_to_state(state, crtc, new_active_planes);
> if (ret)
> return ret;
> diff --git a/drivers/gpu/drm/i915/display/intel_display_power.h b/drivers/gpu/drm/i915/display/intel_display_power.h
> index da64a5edae7a..3446c3ce6a4f 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_power.h
> +++ b/drivers/gpu/drm/i915/display/intel_display_power.h
> @@ -311,6 +311,7 @@ intel_display_power_put_async(struct drm_i915_private *i915,
> enum dbuf_slice {
> DBUF_S1,
> DBUF_S2,
> + DBUF_SLICE_MAX
> };
>
> #define with_intel_display_power(i915, domain, wf) \
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 8375054ba27d..15300c44d9dc 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -3844,10 +3844,9 @@ icl_get_first_dbuf_slice_offset(u32 dbuf_slice_mask,
> return offset;
> }
>
> -static u16 intel_get_ddb_size(struct drm_i915_private *dev_priv)
> +u16 intel_get_ddb_size(struct drm_i915_private *dev_priv)
> {
> u16 ddb_size = INTEL_INFO(dev_priv)->ddb_size;
> -
> drm_WARN_ON(&dev_priv->drm, ddb_size == 0);
>
> if (INTEL_GEN(dev_priv) < 11)
> @@ -3856,6 +3855,37 @@ static u16 intel_get_ddb_size(struct drm_i915_private *dev_priv)
> return ddb_size;
> }
>
> +u32 skl_ddb_dbuf_slice_mask(struct drm_i915_private *dev_priv,
> + const struct skl_ddb_entry *entry)
> +{
> + u32 slice_mask = 0;
> + u16 ddb_size = intel_get_ddb_size(dev_priv);
> + u16 num_supported_slices = INTEL_INFO(dev_priv)->num_supported_dbuf_slices;
> + u16 slice_size = ddb_size / num_supported_slices;
> + u16 start_slice;
> + u16 end_slice;
> +
> + if (!skl_ddb_entry_size(entry))
> + return 0;
> +
> + start_slice = entry->start / slice_size;
> + end_slice = (entry->end - 1) / slice_size;
> +
> + DRM_DEBUG_KMS("ddb size %d slices %d slice size %d start slice %d end slice %d\n",
> + ddb_size, num_supported_slices, slice_size, start_slice, end_slice);
> +
> + /*
> + * Per plane DDB entry can in a really worst case be on multiple slices
> + * but single entry is anyway contigious.
> + */
> + while (start_slice <= end_slice) {
> + slice_mask |= 1 << start_slice;
> + start_slice++;
> + }
> +
> + return slice_mask;
> +}
> +
> static u8 skl_compute_dbuf_slices(const struct intel_crtc_state *crtc_state,
> u8 active_pipes);
>
> diff --git a/drivers/gpu/drm/i915/intel_pm.h b/drivers/gpu/drm/i915/intel_pm.h
> index d60a85421c5a..a9e3835927a8 100644
> --- a/drivers/gpu/drm/i915/intel_pm.h
> +++ b/drivers/gpu/drm/i915/intel_pm.h
> @@ -37,6 +37,9 @@ void skl_pipe_ddb_get_hw_state(struct intel_crtc *crtc,
> struct skl_ddb_entry *ddb_y,
> struct skl_ddb_entry *ddb_uv);
> void skl_ddb_get_hw_state(struct drm_i915_private *dev_priv);
> +u16 intel_get_ddb_size(struct drm_i915_private *dev_priv);
> +u32 skl_ddb_dbuf_slice_mask(struct drm_i915_private *dev_priv,
> + const struct skl_ddb_entry *entry);
> void skl_pipe_wm_get_hw_state(struct intel_crtc *crtc,
> struct skl_pipe_wm *out);
> void g4x_wm_sanitize(struct drm_i915_private *dev_priv);
> --
> 2.24.1.485.gad05a3d8e5
--
Ville Syrjälä
Intel
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