[PATCH 3/3] drm/i915/dsi: Assert that vfp+vsync+vbp == vtotal on BXT/GLK

[Jani Nikula]

On Fri, 14 Mar 2025, Ville Syrjala <ville.syrjala at linux.intel.com> wrote:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
>
> Windows code seems to do some dodgy looking +/-1 adjustments
> to some of the vertical timings. Not sure if that's correct
> or not, but let's at least cross check some of the values
> we got from the hardware to double check whether the GOP
> did the same or not.
>
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>

Acked-by: Jani Nikula <jani.nikula at intel.com>


> ---
>  drivers/gpu/drm/i915/display/vlv_dsi.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/display/vlv_dsi.c b/drivers/gpu/drm/i915/display/vlv_dsi.c
> index 661de51dfd22..cdab04727c7d 100644
> --- a/drivers/gpu/drm/i915/display/vlv_dsi.c
> +++ b/drivers/gpu/drm/i915/display/vlv_dsi.c
> @@ -1024,7 +1024,7 @@ static void bxt_dsi_get_pipe_config(struct intel_encoder *encoder,
>  	unsigned int lane_count = intel_dsi->lane_count;
>  	unsigned int bpp, fmt;
>  	enum port port;
> -	u16 hactive, hfp, hsync, hbp, vfp, vsync;
> +	u16 hactive, hfp, hsync, hbp, vfp, vsync, vbp;
>  	u16 hfp_sw, hsync_sw, hbp_sw;
>  	u16 crtc_htotal_sw, crtc_hsync_start_sw, crtc_hsync_end_sw,
>  				crtc_hblank_start_sw, crtc_hblank_end_sw;
> @@ -1088,6 +1088,7 @@ static void bxt_dsi_get_pipe_config(struct intel_encoder *encoder,
>  
>  	/* vertical values are in terms of lines */
>  	vfp = intel_de_read(display, MIPI_VFP_COUNT(display, port));
> +	vbp = intel_de_read(display, MIPI_VBP_COUNT(display, port));
>  	vsync = intel_de_read(display, MIPI_VSYNC_PADDING_COUNT(display, port));
>  
>  	adjusted_mode->crtc_htotal = hactive + hfp + hsync + hbp;
> @@ -1096,6 +1097,8 @@ static void bxt_dsi_get_pipe_config(struct intel_encoder *encoder,
>  	adjusted_mode->crtc_hblank_start = adjusted_mode->crtc_hdisplay;
>  	adjusted_mode->crtc_hblank_end = adjusted_mode->crtc_htotal;
>  
> +	drm_WARN_ON(display->drm, adjusted_mode->crtc_vdisplay +
> +		    vfp + vsync + vbp != adjusted_mode->crtc_vtotal);
>  	adjusted_mode->crtc_vsync_start = vfp + adjusted_mode->crtc_vdisplay;
>  	adjusted_mode->crtc_vsync_end = vsync + adjusted_mode->crtc_vsync_start;
>  	adjusted_mode->crtc_vblank_start = adjusted_mode->crtc_vdisplay;

-- 
Jani Nikula, Intel