Re: [PATCH v2 2/2] drm/i915: Don't advertise modes that exceed the max plane size

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Wed, Sep 18, 2019 at 11:24:09AM -0400, Sean Paul wrote:
> On Wed, Sep 18, 2019 at 06:07:07PM +0300, Ville Syrjala wrote:
> > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > 
> > Modern platforms allow the transcoders hdisplay/vdisplay to exceed the
> > planes' max resolution. This has the nasty implication that modes on the
> > connectors' mode list may not be usable when the user asks for a
> > fullscreen plane. Seeing as that is the most common use case it seems
> > prudent to filter out modes that don't allow for fullscreen planes to
> > be enabled.
> > 
> > Let's do that in the connetor .mode_valid() hook so that normally
> > such modes are kept hidden but the user is still able to forcibly
> > specify such a mode if they know they don't need fullscreen planes.
> > 
> > This is in line with ealier policies regarding certain clock limits.
> > The idea is to prevent the casual user from encountering a mode that
> > would fail under typical conditions, but allow the expert user to
> > force things if they so wish.
> 
> Isn't this exactly what atomic_check is for? Why not just add a debug message in
> get_max_plane_size to leave a breadcrumb?

There's already a debug message. Won't really help when the screen fails
to light up automagically on account of the preferred mode being too
big.

> 
> Sean
> 
> > 
> > Maybe in the future we should consider automagically using two
> > planes when one can't cover the entire screen? Wouldn't be a
> > great match for the current uapi with explicit planes though,
> > but I guess no worse than using two pipes (which we apparently
> > have to in the future anyway). Either that or we'd have to
> > teach userspace to do it for us.
> > 
> > v2: Fix icl+ max plane heigth (Manasi)
> > 
> > Cc: Manasi Navare <manasi.d.navare@intel.com>
> > Cc: Leho Kraav <leho@kraav.com>
> > Cc: Sean Paul <sean@poorly.run>
> > Cc: José Roberto de Souza <jose.souza@intel.com>
> > Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_display.c | 36 ++++++++++++++++++++
> >  drivers/gpu/drm/i915/display/intel_display.h |  4 +++
> >  drivers/gpu/drm/i915/display/intel_dp.c      |  2 +-
> >  drivers/gpu/drm/i915/display/intel_dsi.c     |  3 +-
> >  drivers/gpu/drm/i915/display/intel_hdmi.c    |  4 ++-
> >  5 files changed, 46 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
> > index f5e65e052d91..0147e4ae3622 100644
> > --- a/drivers/gpu/drm/i915/display/intel_display.c
> > +++ b/drivers/gpu/drm/i915/display/intel_display.c
> > @@ -15753,6 +15753,7 @@ intel_mode_valid(struct drm_device *dev,
> >  			   DRM_MODE_FLAG_CLKDIV2))
> >  		return MODE_BAD;
> >  
> > +	/* Transcoder timing limits */
> >  	if (INTEL_GEN(dev_priv) >= 11) {
> >  		hdisplay_max = 16384;
> >  		vdisplay_max = 8192;
> > @@ -15791,6 +15792,41 @@ intel_mode_valid(struct drm_device *dev,
> >  	return MODE_OK;
> >  }
> >  
> > +enum drm_mode_status
> > +intel_mode_valid_max_plane_size(struct drm_i915_private *dev_priv,
> > +				const struct drm_display_mode *mode)
> > +{
> > +	int plane_width_max, plane_height_max;
> > +
> > +	/*
> > +	 * intel_mode_valid() should be
> > +	 * sufficient on older platforms.
> > +	 */
> > +	if (INTEL_GEN(dev_priv) < 9)
> > +		return MODE_OK;
> > +
> > +	/*
> > +	 * Most people will probably want a fullscreen
> > +	 * plane so let's not advertize modes that are
> > +	 * too big for that.
> > +	 */
> > +	if (INTEL_GEN(dev_priv) >= 11) {
> > +		plane_width_max = 5120;
> > +		plane_height_max = 4320;
> > +	} else {
> > +		plane_width_max = 5120;
> > +		plane_height_max = 4096;
> > +	}
> > +
> > +	if (mode->hdisplay > plane_width_max)
> > +		return MODE_H_ILLEGAL;
> > +
> > +	if (mode->vdisplay > plane_height_max)
> > +		return MODE_V_ILLEGAL;
> > +
> > +	return MODE_OK;
> > +}
> > +
> >  static const struct drm_mode_config_funcs intel_mode_funcs = {
> >  	.fb_create = intel_user_framebuffer_create,
> >  	.get_format_info = intel_get_format_info,
> > diff --git a/drivers/gpu/drm/i915/display/intel_display.h b/drivers/gpu/drm/i915/display/intel_display.h
> > index 66330fcb10d4..b1ae0e59c715 100644
> > --- a/drivers/gpu/drm/i915/display/intel_display.h
> > +++ b/drivers/gpu/drm/i915/display/intel_display.h
> > @@ -32,6 +32,7 @@ enum link_m_n_set;
> >  struct dpll;
> >  struct drm_connector;
> >  struct drm_device;
> > +struct drm_display_mode;
> >  struct drm_encoder;
> >  struct drm_file;
> >  struct drm_format_info;
> > @@ -448,6 +449,9 @@ void lpt_disable_clkout_dp(struct drm_i915_private *dev_priv);
> >  u32 intel_plane_fb_max_stride(struct drm_i915_private *dev_priv,
> >  			      u32 pixel_format, u64 modifier);
> >  bool intel_plane_can_remap(const struct intel_plane_state *plane_state);
> > +enum drm_mode_status
> > +intel_mode_valid_max_plane_size(struct drm_i915_private *dev_priv,
> > +				const struct drm_display_mode *mode);
> >  enum phy intel_port_to_phy(struct drm_i915_private *i915, enum port port);
> >  
> >  void intel_plane_destroy(struct drm_plane *plane);
> > diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> > index d09133a958e1..ccaf9f00b747 100644
> > --- a/drivers/gpu/drm/i915/display/intel_dp.c
> > +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> > @@ -562,7 +562,7 @@ intel_dp_mode_valid(struct drm_connector *connector,
> >  	if (mode->flags & DRM_MODE_FLAG_DBLCLK)
> >  		return MODE_H_ILLEGAL;
> >  
> > -	return MODE_OK;
> > +	return intel_mode_valid_max_plane_size(dev_priv, mode);
> >  }
> >  
> >  u32 intel_dp_pack_aux(const u8 *src, int src_bytes)
> > diff --git a/drivers/gpu/drm/i915/display/intel_dsi.c b/drivers/gpu/drm/i915/display/intel_dsi.c
> > index 5fec02aceaed..a2a937109a5a 100644
> > --- a/drivers/gpu/drm/i915/display/intel_dsi.c
> > +++ b/drivers/gpu/drm/i915/display/intel_dsi.c
> > @@ -55,6 +55,7 @@ int intel_dsi_get_modes(struct drm_connector *connector)
> >  enum drm_mode_status intel_dsi_mode_valid(struct drm_connector *connector,
> >  					  struct drm_display_mode *mode)
> >  {
> > +	struct drm_i915_private *dev_priv = to_i915(connector->dev);
> >  	struct intel_connector *intel_connector = to_intel_connector(connector);
> >  	const struct drm_display_mode *fixed_mode = intel_connector->panel.fixed_mode;
> >  	int max_dotclk = to_i915(connector->dev)->max_dotclk_freq;
> > @@ -73,7 +74,7 @@ enum drm_mode_status intel_dsi_mode_valid(struct drm_connector *connector,
> >  			return MODE_CLOCK_HIGH;
> >  	}
> >  
> > -	return MODE_OK;
> > +	return intel_mode_valid_max_plane_size(dev_priv, mode);
> >  }
> >  
> >  struct intel_dsi_host *intel_dsi_host_init(struct intel_dsi *intel_dsi,
> > diff --git a/drivers/gpu/drm/i915/display/intel_hdmi.c b/drivers/gpu/drm/i915/display/intel_hdmi.c
> > index c500fc9154c8..dbc686515dce 100644
> > --- a/drivers/gpu/drm/i915/display/intel_hdmi.c
> > +++ b/drivers/gpu/drm/i915/display/intel_hdmi.c
> > @@ -2188,8 +2188,10 @@ intel_hdmi_mode_valid(struct drm_connector *connector,
> >  			status = hdmi_port_clock_valid(hdmi, clock * 5 / 4,
> >  						       true, force_dvi);
> >  	}
> > +	if (status != MODE_OK)
> > +		return status;
> >  
> > -	return status;
> > +	return intel_mode_valid_max_plane_size(dev_priv, mode);
> >  }
> >  
> >  static bool hdmi_deep_color_possible(const struct intel_crtc_state *crtc_state,
> > -- 
> > 2.21.0
> > 
> 
> -- 
> Sean Paul, Software Engineer, Google / Chromium OS

-- 
Ville Syrjälä
Intel
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