Re: [Intel-gfx] [PATCH 1/4] drm/i915: Skip some timing checks on BXT/GLK DSI transcoders

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

On Tue, Nov 28, 2023 at 02:47:35PM +0200, Jani Nikula wrote:
> On Tue, 28 Nov 2023, Ville Syrjälä <ville.syrjala@linux.intel.com> wrote:
> > On Tue, Nov 28, 2023 at 02:22:23PM +0200, Jani Nikula wrote:
> >> On Mon, 27 Nov 2023, Ville Syrjala <ville.syrjala@linux.intel.com> wrote:
> >> > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> >> >
> >> > Apparently some BXT/GLK systems have DSI panels whose timings
> >> > don't agree with the normal cpu transcoder hblank>=32 limitation.
> >> > This is perhaps fine as there are no specific hblank/etc. limits
> >> > listed for the BXT/GLK DSI transcoders.
> >> >
> >> > Move those checks out from the global intel_mode_valid() into
> >> > into connector specific .mode_valid() hooks, skipping BXT/GLK
> >> > DSI connectors. We'll leave the basic [hv]display/[hv]total
> >> > checks in intel_mode_valid() as those seem like sensible upper
> >> > limits regardless of the transcoder used.
> >> >
> >> > Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/9720
> >> > Fixes: 8f4b1068e7fc ("drm/i915: Check some transcoder timing minimum limits")
> >> > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> >> > ---
> >> >  drivers/gpu/drm/i915/display/icl_dsi.c       |  7 +++++++
> >> >  drivers/gpu/drm/i915/display/intel_crt.c     |  5 +++++
> >> >  drivers/gpu/drm/i915/display/intel_display.c | 10 ++++++++++
> >> >  drivers/gpu/drm/i915/display/intel_display.h |  3 +++
> >> >  drivers/gpu/drm/i915/display/intel_dp.c      |  4 ++++
> >> >  drivers/gpu/drm/i915/display/intel_dp_mst.c  |  4 ++++
> >> >  drivers/gpu/drm/i915/display/intel_dvo.c     |  6 ++++++
> >> >  drivers/gpu/drm/i915/display/intel_hdmi.c    |  4 ++++
> >> >  drivers/gpu/drm/i915/display/intel_lvds.c    |  5 +++++
> >> >  drivers/gpu/drm/i915/display/intel_sdvo.c    |  8 +++++++-
> >> >  drivers/gpu/drm/i915/display/intel_tv.c      |  8 +++++++-
> >> >  drivers/gpu/drm/i915/display/vlv_dsi.c       | 18 +++++++++++++++++-
> >> >  12 files changed, 79 insertions(+), 3 deletions(-)
> >> >
> >> > diff --git a/drivers/gpu/drm/i915/display/icl_dsi.c b/drivers/gpu/drm/i915/display/icl_dsi.c
> >> > index 481fcb650850..ac456a2275db 100644
> >> > --- a/drivers/gpu/drm/i915/display/icl_dsi.c
> >> > +++ b/drivers/gpu/drm/i915/display/icl_dsi.c
> >> > @@ -1440,6 +1440,13 @@ static void gen11_dsi_post_disable(struct intel_atomic_state *state,
> >> >  static enum drm_mode_status gen11_dsi_mode_valid(struct drm_connector *connector,
> >> >  						 struct drm_display_mode *mode)
> >> >  {
> >> > +	struct drm_i915_private *i915 = to_i915(connector->dev);
> >> > +	enum drm_mode_status status;
> >> > +
> >> > +	status = intel_cpu_transcoder_mode_valid(i915, mode);
> >> > +	if (status != MODE_OK)
> >> > +		return status;
> >> > +
> >> >  	/* FIXME: DSC? */
> >> >  	return intel_dsi_mode_valid(connector, mode);
> >> >  }
> >> > diff --git a/drivers/gpu/drm/i915/display/intel_crt.c b/drivers/gpu/drm/i915/display/intel_crt.c
> >> > index 0e33a0523a75..abaacea5c2cc 100644
> >> > --- a/drivers/gpu/drm/i915/display/intel_crt.c
> >> > +++ b/drivers/gpu/drm/i915/display/intel_crt.c
> >> > @@ -348,8 +348,13 @@ intel_crt_mode_valid(struct drm_connector *connector,
> >> >  	struct drm_device *dev = connector->dev;
> >> >  	struct drm_i915_private *dev_priv = to_i915(dev);
> >> >  	int max_dotclk = dev_priv->max_dotclk_freq;
> >> > +	enum drm_mode_status status;
> >> >  	int max_clock;
> >> >  
> >> > +	status = intel_cpu_transcoder_mode_valid(dev_priv, mode);
> >> > +	if (status != MODE_OK)
> >> > +		return status;
> >> > +
> >> >  	if (mode->flags & DRM_MODE_FLAG_DBLSCAN)
> >> >  		return MODE_NO_DBLESCAN;
> >> >  
> >> > diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
> >> > index 5cf162628b95..23b077f43614 100644
> >> > --- a/drivers/gpu/drm/i915/display/intel_display.c
> >> > +++ b/drivers/gpu/drm/i915/display/intel_display.c
> >> > @@ -7734,6 +7734,16 @@ enum drm_mode_status intel_mode_valid(struct drm_device *dev,
> >> >  	    mode->vtotal > vtotal_max)
> >> >  		return MODE_V_ILLEGAL;
> >> >  
> >> > +	return MODE_OK;
> >> > +}
> >> > +
> >> > +enum drm_mode_status intel_cpu_transcoder_mode_valid(struct drm_i915_private *dev_priv,
> >> > +						     const struct drm_display_mode *mode)
> >> > +{
> >> 
> >> Overall the patch looks fine, even if it's a bit meh we have to
> >> duplicate the calls so much. No way around that I guess.
> >> 
> >> Reviewed-by: Jani Nikula <jani.nikula@intel.com>
> >> 
> >> But please explain the intel_cpu_transcoder_mode_valid() naming. I'm not
> >> sure I follow.
> >
> > These limits (suposedly) only apply to the normal
> > transcoders but not to the BXT/GLK DSI transcoders.
> 
> It's just that... some transcoder limits remain in intel_mode_valid().

I did mention that in the commit message.

"We'll leave the basic [hv]display/[hv]total
 checks in intel_mode_valid() as those seem like sensible upper
 limits regardless of the transcoder used."

-- 
Ville Syrjälä
Intel