> -----Original Message-----
> From: dri-devel <dri-devel-boun...@lists.freedesktop.org> On Behalf Of Imre
> Deak
> Sent: Wednesday, February 21, 2024 2:48 AM
> To: intel-...@lists.freedesktop.org; dri-devel@lists.freedesktop.org
> Subject: [PATCH v2 03/21] drm/i915: Fix display bpp limit computation during
> system resume
>
> The system resume display mode restoration should happen with an output
> configuration matching that of the suspend time saved mode. Since the restored
> mode configuration is subject to the bpp fallback logic, starting out with an
> unlimited bpp and reducing the bpp as required by any (MST) link BW limit, the
> resulting bpp will match the one during suspend only if the BW limit checks
> during
> suspend and resume are applied in an identical way. The latter is not
> guaranteed
> at the moment, since the pre-suspend MST topology may not be in place during
> resume (for instance if the MST sink was disconnected while being suspended),
> which makes the MST link BW check accept the unlimited bpp mode
> configuration unconditionally without ensuring that the required BW fits into
> the
> available MST link BW.
>
> To fix the above, initialize the bpp fallback logic with the max link bpp /
> force-FEC
> limits left behind by the suspend time mode save.
Looks Good to me.
Reviewed-by: Uma Shankar <uma.shan...@intel.com>
> Signed-off-by: Imre Deak <imre.d...@intel.com>
> ---
> drivers/gpu/drm/i915/display/intel_display.c | 3 +--
> drivers/gpu/drm/i915/display/intel_link_bw.c | 22 ++++++++++++++++----
> drivers/gpu/drm/i915/display/intel_link_bw.h | 2 +-
> 3 files changed, 20 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_display.c
> b/drivers/gpu/drm/i915/display/intel_display.c
> index 00ac65a140298..485c38d71f106 100644
> --- a/drivers/gpu/drm/i915/display/intel_display.c
> +++ b/drivers/gpu/drm/i915/display/intel_display.c
> @@ -6252,12 +6252,11 @@ static int intel_atomic_check_config(struct
> intel_atomic_state *state,
>
> static int intel_atomic_check_config_and_link(struct intel_atomic_state
> *state) {
> - struct drm_i915_private *i915 = to_i915(state->base.dev);
> struct intel_link_bw_limits new_limits;
> struct intel_link_bw_limits old_limits;
> int ret;
>
> - intel_link_bw_init_limits(i915, &new_limits);
> + intel_link_bw_init_limits(state, &new_limits);
> old_limits = new_limits;
>
> while (true) {
> diff --git a/drivers/gpu/drm/i915/display/intel_link_bw.c
> b/drivers/gpu/drm/i915/display/intel_link_bw.c
> index 9c6d35a405a18..27ea858897c9f 100644
> --- a/drivers/gpu/drm/i915/display/intel_link_bw.c
> +++ b/drivers/gpu/drm/i915/display/intel_link_bw.c
> @@ -6,6 +6,7 @@
> #include "i915_drv.h"
>
> #include "intel_atomic.h"
> +#include "intel_crtc.h"
> #include "intel_display_types.h"
> #include "intel_dp_mst.h"
> #include "intel_fdi.h"
> @@ -13,19 +14,32 @@
>
> /**
> * intel_link_bw_init_limits - initialize BW limits
> - * @i915: device instance
> + * @state: Atomic state
> * @limits: link BW limits
> *
> * Initialize @limits.
> */
> -void intel_link_bw_init_limits(struct drm_i915_private *i915, struct
> intel_link_bw_limits *limits)
> +void intel_link_bw_init_limits(struct intel_atomic_state *state,
> + struct intel_link_bw_limits *limits)
> {
> + struct drm_i915_private *i915 = to_i915(state->base.dev);
> enum pipe pipe;
>
> limits->force_fec_pipes = 0;
> limits->bpp_limit_reached_pipes = 0;
> - for_each_pipe(i915, pipe)
> - limits->max_bpp_x16[pipe] = INT_MAX;
> + for_each_pipe(i915, pipe) {
> + const struct intel_crtc_state *crtc_state =
> + intel_atomic_get_new_crtc_state(state,
> +
> intel_crtc_for_pipe(i915, pipe));
> +
> + if (state->base.duplicated && crtc_state) {
> + limits->max_bpp_x16[pipe] = crtc_state-
> >max_link_bpp_x16;
> + if (crtc_state->fec_enable)
> + limits->force_fec_pipes |= BIT(pipe);
> + } else {
> + limits->max_bpp_x16[pipe] = INT_MAX;
> + }
> + }
> }
>
> /**
> diff --git a/drivers/gpu/drm/i915/display/intel_link_bw.h
> b/drivers/gpu/drm/i915/display/intel_link_bw.h
> index 2cf57307cc249..6b0ccfff59dab 100644
> --- a/drivers/gpu/drm/i915/display/intel_link_bw.h
> +++ b/drivers/gpu/drm/i915/display/intel_link_bw.h
> @@ -22,7 +22,7 @@ struct intel_link_bw_limits {
> int max_bpp_x16[I915_MAX_PIPES];
> };
>
> -void intel_link_bw_init_limits(struct drm_i915_private *i915,
> +void intel_link_bw_init_limits(struct intel_atomic_state *state,
> struct intel_link_bw_limits *limits); int
> intel_link_bw_reduce_bpp(struct intel_atomic_state *state,
> struct intel_link_bw_limits *limits,
> --
> 2.39.2
