Commit ca4edafa authored by Ankit Nautiyal's avatar Ankit Nautiyal
Browse files

drm/i915/vblank: Add helper to get correct vblank length 



Currently crtc_vblank_start is assumed to be the vblank_start for the fixed
refresh rate case. That value can be different from the variable refresh
rate case whenever always_use_vrr_tg()==false. On icl/tgl it's always
different due to the extra vblank delay, and also on adl+ it could be
different if we were to use an optimized guardband.

So places where crtc_vblank_start is used to compute vblank length needs
change so as to account for cases where vrr is enabled. Specifically
with vrr.enable the effective vblank length is actually guardband.

Add a helper to get the correct vblank length for both vrr and fixed
refresh rate cases. Use this helper where vblank_start is used to
compute the vblank length.

Signed-off-by: default avatarAnkit Nautiyal <ankit.k.nautiyal@intel.com>
Reviewed-by: default avatarVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://lore.kernel.org/r/20251016055415.2101347-5-ankit.k.nautiyal@intel.com
parent 2cdcab0d

drivers/gpu/drm/i915/display/intel_vblank.c

+10 −0
Original line number Diff line number Diff line
@@ -767,3 +767,13 @@ int intel_vblank_evade(struct intel_vblank_evade_ctx *evade) 


	return scanline;

}



int intel_crtc_vblank_length(const struct intel_crtc_state *crtc_state)

{

	const struct drm_display_mode *adjusted_mode = &crtc_state->hw.adjusted_mode;



	if (crtc_state->vrr.enable)

		return crtc_state->vrr.guardband;

	else

		return adjusted_mode->crtc_vtotal - adjusted_mode->crtc_vblank_start;

}

drivers/gpu/drm/i915/display/intel_vblank.h

+2 −0
Original line number Diff line number Diff line
@@ -48,4 +48,6 @@ const struct intel_crtc_state * 
intel_pre_commit_crtc_state(struct intel_atomic_state *state,

			    struct intel_crtc *crtc);



int intel_crtc_vblank_length(const struct intel_crtc_state *crtc_state);



#endif /* __INTEL_VBLANK_H__ */

drivers/gpu/drm/i915/display/skl_watermark.c

+2 −1
Original line number Diff line number Diff line
@@ -28,6 +28,7 @@ 
#include "intel_flipq.h"

#include "intel_pcode.h"

#include "intel_plane.h"

#include "intel_vblank.h"

#include "intel_wm.h"

#include "skl_universal_plane_regs.h"

#include "skl_watermark.h"
@@ -2241,7 +2242,7 @@ skl_is_vblank_too_short(const struct intel_crtc_state *crtc_state, 
		scaler_prefill_latency(crtc_state) +

		dsc_prefill_latency(crtc_state) +

		wm0_lines >

		adjusted_mode->crtc_vtotal - adjusted_mode->crtc_vblank_start;

		intel_crtc_vblank_length(crtc_state);

}



static int skl_max_wm0_lines(const struct intel_crtc_state *crtc_state)