[PATCH 0/3] drm/i915: Fix scanline_offset for LNL+/BMG+

[Lucas De Marchi]

On Fri, Feb 07, 2025 at 11:54:03PM +0200, Ville Syrjälä wrote:
>From: Ville Syrjälä <ville.syrjala at linux.intel.com>
>
>Something has changed in the hardware on LNL/BMG because
>HDMI outputs no longer have the extra scanline offset.
>
>I confirmed that MTL still has the old behaviour, which
>is a bit weird since both MTL and BMG have display ver 14
>vs. LNL is version 20. But can't argue with actual
>hardware behaviour.

<6>[  210.368608] xe 0000:03:00.0: [drm] Found battlemage (device ID e20b) discrete display version 14.01 stepping B0
vs
<6>[  412.999204] i915 0000:00:02.0: [drm] Found meteorlake (device ID 7d55) integrated display version 14.00 stepping C0

So 14.01 vs 14.00. In the driver:

static const struct {                                                            
         u16 ver;
         u16 rel;
         const struct intel_display_device_info *display;
} gmdid_display_map[] = {
         { 14,  0, &xe_lpdp_display },
         { 14,  1, &xe2_hpd_display },
	...
}

So maybe we need to check for the full version >= 1401 instead?

+Matt Roper, +Gustavo who may know the right bspec to confirm this
change in behavior

Lucas De Marchi

>
>Ville Syrjälä (3):
>  drm/i915: Fix scanline_offset for LNL+ and BMG+
>  drm/i915: Reverse the scanline_offset if ladder
>  drm/i915: Replace the HAS_DDI() in intel_crtc_scanline_offset() with
>    specific platform checks
>
> drivers/gpu/drm/i915/display/intel_vblank.c | 13 ++++++++-----
> 1 file changed, 8 insertions(+), 5 deletions(-)
>
>-- 
>2.45.3
>