[PATCH 1/3] drm/i915: Fix scanline_offset for LNL+ and BMG+

[Shankar, Uma]

> -----Original Message-----
> From: Intel-gfx <intel-gfx-bounces at lists.freedesktop.org> On Behalf Of Ville
> Syrjala
> Sent: Saturday, February 8, 2025 3:24 AM
> To: intel-gfx at lists.freedesktop.org
> Cc: intel-xe at lists.freedesktop.org; stable at vger.kernel.org
> Subject: [PATCH 1/3] drm/i915: Fix scanline_offset for LNL+ and BMG+
> 
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> Turns out LNL+ and BMG+ no longer have the weird extra scanline offset for
> HDMI outputs. Fix intel_crtc_scanline_offset() accordingly so that scanline
> evasion/etc. works correctly on HDMI outputs on these new platforms.

Interesting find, will try to follow up internally with hardware to explain the behaviour.

Change Looks Good to me, however, would be good to align on the display version
check as being discussed in the trailing mail thread.
Reviewed-by: Uma Shankar <uma.shankar at intel.com>

> Cc: stable at vger.kernel.org
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_vblank.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_vblank.c
> b/drivers/gpu/drm/i915/display/intel_vblank.c
> index 4efd4f7d497a..7b240ce681a0 100644
> --- a/drivers/gpu/drm/i915/display/intel_vblank.c
> +++ b/drivers/gpu/drm/i915/display/intel_vblank.c
> @@ -222,7 +222,9 @@ int intel_crtc_scanline_offset(const struct
> intel_crtc_state *crtc_state)
>  	 * However if queried just before the start of vblank we'll get an
>  	 * answer that's slightly in the future.
>  	 */
> -	if (DISPLAY_VER(display) == 2)
> +	if (DISPLAY_VER(display) >= 20 || display->platform.battlemage)
> +		return 1;
> +	else if (DISPLAY_VER(display) == 2)
>  		return -1;
>  	else if (HAS_DDI(display) && intel_crtc_has_type(crtc_state,
> INTEL_OUTPUT_HDMI))
>  		return 2;
> --
> 2.45.3