[PATCH v2 03/21] drm/i915: Fix display bpp limit computation during system resume

[Shankar, Uma]

> -----Original Message-----
> From: dri-devel <dri-devel-bounces at lists.freedesktop.org> On Behalf Of Imre
> Deak
> Sent: Wednesday, February 21, 2024 2:48 AM
> To: intel-gfx at lists.freedesktop.org; dri-devel at 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.shankar at intel.com>

> Signed-off-by: Imre Deak <imre.deak at 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