On Mon, Mar 25, 2024 at 01:23:26PM +0200, Stanislav Lisovskiy wrote:
> According to BSpec we need to do correspondent MBUS updates before
> or after DBUF reallocation, depending on whether we are enabling
> or disabling mbus joining(typical scenario is swithing between
> multiple and single displays).
>
> Also we need to be able to update dbuf min tracker and mdclk ratio
> separately if mbus_join state didn't change, so lets add one
> degree of freedom and make it possible.
>
> Reviewed-by: Ville Syrjälä <ville.syrj...@linux.intel.com>
> Signed-off-by: Stanislav Lisovskiy <stanislav.lisovs...@intel.com>
> ---
> drivers/gpu/drm/i915/display/skl_watermark.c | 54 +++++++++++++-------
> 1 file changed, 35 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/skl_watermark.c
> b/drivers/gpu/drm/i915/display/skl_watermark.c
> index bc341abcab2fe..2b947870527fc 100644
> --- a/drivers/gpu/drm/i915/display/skl_watermark.c
> +++ b/drivers/gpu/drm/i915/display/skl_watermark.c
> @@ -3570,16 +3570,38 @@ void intel_dbuf_mdclk_cdclk_ratio_update(struct
> drm_i915_private *i915, u8 ratio
> DBUF_MIN_TRACKER_STATE_SERVICE(ratio - 1));
> }
>
> +static void intel_dbuf_mdclk_min_tracker_update(struct intel_atomic_state
> *state)
> +{
> + struct drm_i915_private *i915 = to_i915(state->base.dev);
> + const struct intel_dbuf_state *old_dbuf_state =
> + intel_atomic_get_old_dbuf_state(state);
> + const struct intel_dbuf_state *new_dbuf_state =
> + intel_atomic_get_new_dbuf_state(state);
> +
> + if (DISPLAY_VER(i915) >= 20 &&
> + old_dbuf_state->mdclk_cdclk_ratio !=
> new_dbuf_state->mdclk_cdclk_ratio) {
> + /*
> + * For Xe2LPD and beyond, when there is a change in the ratio
> + * between MDCLK and CDCLK, updates to related registers need to
> + * happen at a specific point in the CDCLK change sequence. In
> + * that case, we defer to the call to
> + * intel_dbuf_mdclk_cdclk_ratio_update() to the CDCLK logic.
> + */
> + return;
> + }
That still needs to be removed or else we'll not update the ratio at
all during the mbus_join changes. I don't think I saw any removal
in subsequent patches.
> +
> + intel_dbuf_mdclk_cdclk_ratio_update(i915,
> new_dbuf_state->mdclk_cdclk_ratio,
And it just occurred to me that this thing will in fact be wrong
during the pre/post ddb hooks *and* cdclk is getting decreased
from the post plane update hook.
I can't immediately think of a super nice way to handle this.
Perhaps the most stragithforward idea is to just get the mdclk/cdclk
ratio from i915->display.cdclk.hw during the pre/post ddb hooks.
cdclk serialization should guard against parallel updates from
two both places and thus isplay.cdclk.hw should be safe to use.
The other option would be to determine if a cdclk decrease
is going to happen or not, and depending on that use the
old vs. new dbuf_state when updating the ratio in the
pre/post ddb hooks.
> + new_dbuf_state->joined_mbus);
> +}
> +
> /*
> * Configure MBUS_CTL and all DBUF_CTL_S of each slice to join_mbus state
> before
> * update the request state of all DBUS slices.
> */
> -static void update_mbus_pre_enable(struct intel_atomic_state *state)
> +static void intel_dbuf_mbus_join_update(struct intel_atomic_state *state)
> {
> struct drm_i915_private *i915 = to_i915(state->base.dev);
> u32 mbus_ctl;
> - const struct intel_dbuf_state *old_dbuf_state =
> - intel_atomic_get_old_dbuf_state(state);
> const struct intel_dbuf_state *new_dbuf_state =
> intel_atomic_get_new_dbuf_state(state);
>
> @@ -3600,21 +3622,6 @@ static void update_mbus_pre_enable(struct
> intel_atomic_state *state)
> intel_de_rmw(i915, MBUS_CTL,
> MBUS_HASHING_MODE_MASK | MBUS_JOIN |
> MBUS_JOIN_PIPE_SELECT_MASK, mbus_ctl);
> -
> - if (DISPLAY_VER(i915) >= 20 &&
> - old_dbuf_state->mdclk_cdclk_ratio !=
> new_dbuf_state->mdclk_cdclk_ratio) {
> - /*
> - * For Xe2LPD and beyond, when there is a change in the ratio
> - * between MDCLK and CDCLK, updates to related registers need to
> - * happen at a specific point in the CDCLK change sequence. In
> - * that case, we defer to the call to
> - * intel_dbuf_mdclk_cdclk_ratio_update() to the CDCLK logic.
> - */
> - return;
> - }
> -
> - intel_dbuf_mdclk_cdclk_ratio_update(i915,
> new_dbuf_state->mdclk_cdclk_ratio,
> - new_dbuf_state->joined_mbus);
> }
>
> void intel_dbuf_pre_plane_update(struct intel_atomic_state *state)
> @@ -3632,7 +3639,11 @@ void intel_dbuf_pre_plane_update(struct
> intel_atomic_state *state)
>
> WARN_ON(!new_dbuf_state->base.changed);
>
> - update_mbus_pre_enable(state);
> + if (!old_dbuf_state->joined_mbus && new_dbuf_state->joined_mbus) {
I think you squashed that stuff into the wrong patch.
This one should have a pure refactoring patch.
> + intel_dbuf_mbus_join_update(state);
> + intel_dbuf_mdclk_min_tracker_update(state);
> + }
> +
> gen9_dbuf_slices_update(i915,
> old_dbuf_state->enabled_slices |
> new_dbuf_state->enabled_slices);
> @@ -3653,6 +3664,11 @@ void intel_dbuf_post_plane_update(struct
> intel_atomic_state *state)
>
> WARN_ON(!new_dbuf_state->base.changed);
>
> + if (old_dbuf_state->joined_mbus && !new_dbuf_state->joined_mbus) {
> + intel_dbuf_mbus_join_update(state);
> + intel_dbuf_mdclk_min_tracker_update(state);
> + }
> +
> gen9_dbuf_slices_update(i915,
> new_dbuf_state->enabled_slices);
> }
> --
> 2.37.3
--
Ville Syrjälä
Intel
