[Intel-gfx] [PATCH 2/3] drm/i915: Check timings against hardware maximums

[Paulo Zanoni]

Em Sex, 2018-06-15 às 20:44 +0300, Ville Syrjala escreveu:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> Validate that all display timings fit within the number of bits
> we have in the transcoder timing registers.
> 
> The limits are:
> hsw+:
>  4k: vdisplay, vblank_start
>  8k: everything else
> gen3+:
>  4k: h/vdisplay, h/vblank_start
>  8k: everything else
> gen2:
>  2k: h/vdisplay, h/vblank_start
>  4k: everything else
> 
> Also document the fact that the mode_config.max_width/height limits
> refer to just the max framebuffer dimensions we support. Which may
> be larger than the max hdisplay/vdisplay.

Verified against the specs. I can also confirm that the gen2+ specs
still exist at the old URLs :).

Reviewed-by: Paulo Zanoni <paulo.r.zanoni at intel.com>

While at it, can't you try to implement the other restrictions listed
in those active/sync registers? Like hdisplay needs be multiples of 2
on gen2, hblank minimum being 32 on HSW (138 with audio), minimum
vblank veing 5 or 8, etc?

> 
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> ---
>  drivers/gpu/drm/i915/intel_display.c | 35
> +++++++++++++++++++++++++++++++++++
>  1 file changed, 35 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c
> b/drivers/gpu/drm/i915/intel_display.c
> index f6655f482b67..6e3aa6815b30 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -14572,6 +14572,10 @@ static enum drm_mode_status
>  intel_mode_valid(struct drm_device *dev,
>  		 const struct drm_display_mode *mode)
>  {
> +	struct drm_i915_private *dev_priv = to_i915(dev);
> +	int hdisplay_max, htotal_max;
> +	int vdisplay_max, vtotal_max;
> +
>  	/*
>  	 * Can't reject DBLSCAN here because Xorg ddxen can add
> piles
>  	 * of DBLSCAN modes to the output's mode list when they
> detect
> @@ -14601,6 +14605,36 @@ intel_mode_valid(struct drm_device *dev,
>  			   DRM_MODE_FLAG_CLKDIV2))
>  		return MODE_BAD;
>  
> +	if (INTEL_GEN(dev_priv) >= 9 ||
> +	    IS_BROADWELL(dev_priv) || IS_HASWELL(dev_priv)) {
> +		hdisplay_max = 8192; /* FDI max 4096 handled
> elsewhere */
> +		vdisplay_max = 4096;
> +		htotal_max = 8192;
> +		vtotal_max = 8192;
> +	} else if (INTEL_GEN(dev_priv) >= 3) {
> +		hdisplay_max = 4096;
> +		vdisplay_max = 4096;
> +		htotal_max = 8192;
> +		vtotal_max = 8192;
> +	} else {
> +		hdisplay_max = 2048;
> +		vdisplay_max = 2048;
> +		htotal_max = 4096;
> +		vtotal_max = 4096;
> +	}
> +
> +	if (mode->hdisplay > hdisplay_max ||
> +	    mode->hsync_start > htotal_max ||
> +	    mode->hsync_end > htotal_max ||
> +	    mode->htotal > htotal_max)
> +		return MODE_H_ILLEGAL;
> +
> +	if (mode->vdisplay > vdisplay_max ||
> +	    mode->vsync_start > vtotal_max ||
> +	    mode->vsync_end > vtotal_max ||
> +	    mode->vtotal > vtotal_max)
> +		return MODE_V_ILLEGAL;
> +
>  	return MODE_OK;
>  }
>  
> @@ -15039,6 +15073,7 @@ int intel_modeset_init(struct drm_device
> *dev)
>  		}
>  	}
>  
> +	/* maximum framebuffer dimensions */
>  	if (IS_GEN2(dev_priv)) {
>  		dev->mode_config.max_width = 2048;
>  		dev->mode_config.max_height = 2048;