Re: [PATCH 5/7] drm/i915: Move intel_crtc_scanline_offset()

[Jani Nikula <jani.nikula@linux.intel.com>]

On Tue, 28 May 2024, Ville Syrjala <ville.syrjala@linux.intel.com> wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
>
> I want to use intel_crtc_scanline_offset() in
> intel_crtc_scanline_to_hw(). Relocate intel_crtc_scanline_offset()
> a bit to avoid a forward declaration.
>
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

Reviewed-by: Jani Nikula <jani.nikula@intel.com>

> ---
>  drivers/gpu/drm/i915/display/intel_vblank.c | 76 ++++++++++-----------
>  1 file changed, 38 insertions(+), 38 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_vblank.c b/drivers/gpu/drm/i915/display/intel_vblank.c
> index b0e95a4c680d..eb80952b0cfd 100644
> --- a/drivers/gpu/drm/i915/display/intel_vblank.c
> +++ b/drivers/gpu/drm/i915/display/intel_vblank.c
> @@ -188,6 +188,44 @@ static u32 __intel_get_crtc_scanline_from_timestamp(struct intel_crtc *crtc)
>  	return scanline;
>  }
>  
> +static int intel_crtc_scanline_offset(const struct intel_crtc_state *crtc_state)
> +{
> +	struct drm_i915_private *i915 = to_i915(crtc_state->uapi.crtc->dev);
> +
> +	/*
> +	 * The scanline counter increments at the leading edge of hsync.
> +	 *
> +	 * On most platforms it starts counting from vtotal-1 on the
> +	 * first active line. That means the scanline counter value is
> +	 * always one less than what we would expect. Ie. just after
> +	 * start of vblank, which also occurs at start of hsync (on the
> +	 * last active line), the scanline counter will read vblank_start-1.
> +	 *
> +	 * On gen2 the scanline counter starts counting from 1 instead
> +	 * of vtotal-1, so we have to subtract one.
> +	 *
> +	 * On HSW+ the behaviour of the scanline counter depends on the output
> +	 * type. For DP ports it behaves like most other platforms, but on HDMI
> +	 * there's an extra 1 line difference. So we need to add two instead of
> +	 * one to the value.
> +	 *
> +	 * On VLV/CHV DSI the scanline counter would appear to increment
> +	 * approx. 1/3 of a scanline before start of vblank. Unfortunately
> +	 * that means we can't tell whether we're in vblank or not while
> +	 * we're on that particular line. We must still set scanline_offset
> +	 * to 1 so that the vblank timestamps come out correct when we query
> +	 * the scanline counter from within the vblank interrupt handler.
> +	 * However if queried just before the start of vblank we'll get an
> +	 * answer that's slightly in the future.
> +	 */
> +	if (DISPLAY_VER(i915) == 2)
> +		return -1;
> +	else if (HAS_DDI(i915) && intel_crtc_has_type(crtc_state, INTEL_OUTPUT_HDMI))
> +		return 2;
> +	else
> +		return 1;
> +}
> +
>  /*
>   * intel_de_read_fw(), only for fast reads of display block, no need for
>   * forcewake etc.
> @@ -467,44 +505,6 @@ void intel_wait_for_pipe_scanline_moving(struct intel_crtc *crtc)
>  	wait_for_pipe_scanline_moving(crtc, true);
>  }
>  
> -static int intel_crtc_scanline_offset(const struct intel_crtc_state *crtc_state)
> -{
> -	struct drm_i915_private *i915 = to_i915(crtc_state->uapi.crtc->dev);
> -
> -	/*
> -	 * The scanline counter increments at the leading edge of hsync.
> -	 *
> -	 * On most platforms it starts counting from vtotal-1 on the
> -	 * first active line. That means the scanline counter value is
> -	 * always one less than what we would expect. Ie. just after
> -	 * start of vblank, which also occurs at start of hsync (on the
> -	 * last active line), the scanline counter will read vblank_start-1.
> -	 *
> -	 * On gen2 the scanline counter starts counting from 1 instead
> -	 * of vtotal-1, so we have to subtract one.
> -	 *
> -	 * On HSW+ the behaviour of the scanline counter depends on the output
> -	 * type. For DP ports it behaves like most other platforms, but on HDMI
> -	 * there's an extra 1 line difference. So we need to add two instead of
> -	 * one to the value.
> -	 *
> -	 * On VLV/CHV DSI the scanline counter would appear to increment
> -	 * approx. 1/3 of a scanline before start of vblank. Unfortunately
> -	 * that means we can't tell whether we're in vblank or not while
> -	 * we're on that particular line. We must still set scanline_offset
> -	 * to 1 so that the vblank timestamps come out correct when we query
> -	 * the scanline counter from within the vblank interrupt handler.
> -	 * However if queried just before the start of vblank we'll get an
> -	 * answer that's slightly in the future.
> -	 */
> -	if (DISPLAY_VER(i915) == 2)
> -		return -1;
> -	else if (HAS_DDI(i915) && intel_crtc_has_type(crtc_state, INTEL_OUTPUT_HDMI))
> -		return 2;
> -	else
> -		return 1;
> -}
> -
>  void intel_crtc_update_active_timings(const struct intel_crtc_state *crtc_state,
>  				      bool vrr_enable)
>  {

-- 
Jani Nikula, Intel