Re: [PATCH v10 6/6] drm/i915/display: force qgv check after the hw state readout

["Lisovskiy, Stanislav" <stanislav.lisovskiy@intel.com>]

On Fri, Apr 05, 2024 at 02:35:33PM +0300, Vinod Govindapillai wrote:
> The current intel_bw_atomic_check do not check the possbility
> of a sagv configuration change after the hw state readout.
> Hence cannot update the sagv configuration until some other
> relevant changes like data rates, number of planes etc. happen.
> Introduce a flag to force qgv check in such cases.
> 
> Signed-off-by: Vinod Govindapillai <vinod.govindapillai@intel.com>

Hmmm.. the whole point of that series is actually to put HW/SW
in sync, before we actually are able to calculate the real requirements.

When we initially for QGV/PSF GV to the highest point(thus disabling SAGV),
we exactly want to make sure that HW/SW are in sync(which wasn't the case
before that). Then later when the real plane bw requirements are calculated,
we can possibly relax the QGV point requirements, enabling more points.

I don't see why we need to force the recalculation here.

Or am I missing something?

Stan

> ---
>  drivers/gpu/drm/i915/display/intel_bw.c | 8 ++++++--
>  drivers/gpu/drm/i915/display/intel_bw.h | 6 ++++++
>  2 files changed, 12 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_bw.c b/drivers/gpu/drm/i915/display/intel_bw.c
> index 6fb228a1a28f..1b190be745a0 100644
> --- a/drivers/gpu/drm/i915/display/intel_bw.c
> +++ b/drivers/gpu/drm/i915/display/intel_bw.c
> @@ -755,6 +755,7 @@ void intel_bw_crtc_update(struct intel_bw_state *bw_state,
>  		intel_bw_crtc_data_rate(crtc_state);
>  	bw_state->num_active_planes[crtc->pipe] =
>  		intel_bw_crtc_num_active_planes(crtc_state);
> +	bw_state->force_check_qgv = true;
>  
>  	drm_dbg_kms(&i915->drm, "pipe %c data rate %u num active planes %u\n",
>  		    pipe_name(crtc->pipe),
> @@ -1339,8 +1340,9 @@ int intel_bw_atomic_check(struct intel_atomic_state *state)
>  	new_bw_state = intel_atomic_get_new_bw_state(state);
>  
>  	if (new_bw_state &&
> -	    intel_can_enable_sagv(i915, old_bw_state) !=
> -	    intel_can_enable_sagv(i915, new_bw_state))
> +	    (intel_can_enable_sagv(i915, old_bw_state) !=
> +	     intel_can_enable_sagv(i915, new_bw_state) ||
> +	     new_bw_state->force_check_qgv))
>  		changed = true;
>  
>  	/*
> @@ -1354,6 +1356,8 @@ int intel_bw_atomic_check(struct intel_atomic_state *state)
>  	if (ret)
>  		return ret;
>  
> +	new_bw_state->force_check_qgv = false;
> +
>  	return 0;
>  }
>  
> diff --git a/drivers/gpu/drm/i915/display/intel_bw.h b/drivers/gpu/drm/i915/display/intel_bw.h
> index fa1e924ec961..161813cca473 100644
> --- a/drivers/gpu/drm/i915/display/intel_bw.h
> +++ b/drivers/gpu/drm/i915/display/intel_bw.h
> @@ -47,6 +47,12 @@ struct intel_bw_state {
>  	 */
>  	u16 qgv_points_mask;
>  
> +	/*
> +	 * Flag to force the QGV comparison in atomic check right after the
> +	 * hw state readout
> +	 */
> +	bool force_check_qgv;
> +
>  	int min_cdclk[I915_MAX_PIPES];
>  	unsigned int data_rate[I915_MAX_PIPES];
>  	u8 num_active_planes[I915_MAX_PIPES];
> -- 
> 2.34.1
>