[Intel-gfx] [PATCH v2 05/20] drm/i915: Make skl_compute_dbuf_slices() behave consistently for all platforms

[Lisovskiy, Stanislav]

On Tue, 2020-02-25 at 19:11 +0200, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> Currently skl_compute_dbuf_slices() returns 0 for any inactive pipe
> on
> icl+, but returns BIT(S1) on pre-icl for any pipe (whether it's
> active or
> not). Let's make the behaviour consistent and always return 0 for any
> inactive pipe.
> 
> Cc: Stanislav Lisovskiy <stanislav.lisovskiy at intel.com>
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> ---
>  drivers/gpu/drm/i915/intel_pm.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_pm.c
> b/drivers/gpu/drm/i915/intel_pm.c
> index a2e78969c0df..640f4c4fd508 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -4408,7 +4408,7 @@ static u8 skl_compute_dbuf_slices(const struct
> intel_crtc_state *crtc_state,
>  	 * For anything else just return one slice yet.
>  	 * Should be extended for other platforms.
>  	 */
> -	return BIT(DBUF_S1);
> +	return active_pipes & BIT(pipe) ? BIT(DBUF_S1) : 0;

I think the initial idea was this won't be even called if there 
are no active pipes at all - skl_ddb_get_pipe_allocation_limits would
bail out immediately. If there were some active pipes - then we will
have to use slice S1 anyway - because there were simply no other slices
available. If some pipes were inactive - they are currently skipped by
!crtc_state->hw.active check - so I would just keep it simple and don't
call this function for non-active pipes at all.

Currently we are just ORing slice bitmasks only from active pipes.

Stan

>  }
>  
>  static u64