At the moment modesetting pipe C on IVB will fail if pipe B uses 4 FDI
lanes. Make the BW sharing more dynamic by trying to reduce pipe B's
link bpp in this case, until pipe B uses only up to 2 FDI lanes.
For this instead of the encoder compute config retry loop - which
reduced link bpp only for the encoder's pipe - reduce the maximum link
bpp for pipe B/C as required after all CRTC states are computed and
recompute the CRTC states with the new bpp limit.
Atm, all FDI encoder's compute config function returns an error if a BW
constrain prevents increasing the pipe bpp value. The corresponding
crtc_state->bw_constrained check can be replaced with checking
crtc_state->max_link_bpp_x16, add TODO comments for this. SDVO is an
exception where this case is only handled in the outer config retry
loop, failing the modeset with a WARN, add a FIXME comment to handle
this in the encoder code similarly to other encoders.
v2:
- Don't assume that a CRTC is already in the atomic state, while
reducing its link bpp.
- Add DocBook description to intel_fdi_atomic_check_link().
v3:
- Enable BW management for FDI links in a separate patch. (Ville)
v4: (Ville)
- Fail the SDVO encoder config computation if it doesn't support the
link bpp limit.
- Add TODO: comments about checking link_bpp_x16 instead of
bw_constrained.
v5:
- Replace link bpp limit check with a FIXME: comment in
intel_sdvo_compute_config(). (Ville)
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
[Amended commit message wrt. changes in v5]
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230921195159.2646027-11-imre.deak@intel.com
At the moment a modeset fails if the config computation of a pipe can't
fit its required BW to the available link BW even though the limitation
may be resolved by reducing the BW requirement of other pipes.
To improve the above this patch adds helper functions checking the
overall BW limits after all CRTC states have been computed. If the check
fails the maximum link bpp for a selected pipe will be reduced and all
the CRTC states will be recomputed until either the overall BW limit
check passes, or further bpp reduction is not possible (because all
pipes/encoders sharing the link BW reached their minimum link bpp).
Atm, the MST encoder allocates twice the required BW for YUV420 format
streams. A follow-up patchset will fix that, add a code comment about
this.
This change prepares for upcoming patches enabling the above BW
management on FDI and MST links.
v2:
- Rename intel_crtc_state::max_link_bpp to max_link_bpp_x16 and
intel_link_bw_limits::max_bpp to max_bpp_x16. (Jani)
v3:
- Add the helper functions in a separate patch. (Ville)
- Add the functions to intel_link_bw.c instead of intel_atomic.c (Ville)
- Return -ENOSPC instead of -EINVAL to userspace in case of a link BW
limit failure.
v4:
- Make intel_atomic_check_config() static.
v5: (Ville)
- Rename intel_link_bw_limits::min_bpp_pipes to min_bpp_reached_pipes
and intel_link_bw_reset_pipe_limit_to_min() to
intel_link_bw_set_min_bpp_for_pipe().
- Rename pipe_bpp to link_bpp in intel_link_bw_reduce_bpp().
- Add FIXME: comment about MST encoder's YUV420 BW allocation and
tracking the link bpp limit accordingly.
v6:
- Move intel_link_bw_compute_pipe_bpp() to intel_fdi.c (Ville)
- WARN_ON(BIT(pipe) & min_bpp_reached_pipes) in
intel_link_bw_set_bpp_limit_for_pipe(). (Ville)
- Rename intel_link_bw_set_min_bpp_for_pipe() to
intel_link_bw_set_bpp_limit_for_pipe() and
intel_link_bw_limits::min_bpp_reached_pipes to
bpp_limit_reached_pipes. (Ville)
- Remove unused header includes.
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230921195159.2646027-10-imre.deak@intel.com
