Re: [PATCH 3/3] drm/i915: Get panel_type from OpRegion panel details

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

On Fri, Apr 08, 2016 at 06:01:41PM +0300, Jani Nikula wrote:
> On Fri, 08 Apr 2016, Ville Syrjälä <ville.syrjala@linux.intel.com> wrote:
> > On Fri, Apr 08, 2016 at 05:50:06PM +0300, Jani Nikula wrote:
> >> On Fri, 08 Apr 2016, ville.syrjala@linux.intel.com wrote:
> >> > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> >> >
> >> > We've had problems on several occasions with using the panel type
> >> > from the VBT block 40. Usually it seems to be 2, which often
> >> > doesn't give us the correct timings for the panel. After some
> >> > more digging I found a way to get a panel type via the OpRegion
> >> > SWSCI GBDA "Get Panel Details" method. Let's try to use it.
> >> >
> >> > The spec has this to say about the output:
> >> > "Bits [15:8] - Panel Type
> >> >  Bits contain the panel type user setting from CMOS
> >> >  00h = Not Valid, use default Panel Type & Timings from VBT
> >> >  01h - 0Fh = Panel Number"
> >> >
> >> > The other bits in the output don't look relevant for the problem at
> >> > hand.
> >> >
> >> > The input is specified as:
> >> > "Bits [31:4] - Reserved
> >> >  Reserved (must be zero)
> >> >  Bits [3:0] - Panel Number
> >> >  These bits contain the sequential index of Panel, starting at 0 and
> >> >  counting upwards from the first integrated Internal Flat-Panel Display
> >> >  Encoder present, and then from the first external Display Encoder
> >> >  (e.g., S/DVO-B then S/DVO-C) which supports Internal Flat-Panels.
> >> >  0h - 0Fh = Panel number"
> >> >
> >> > For now I've just hardcoded the input panel number as 0. That would seem
> >> > like a decent choise for LVDS. Not so sure about eDP when port != A.
> >> 
> >> Frankly, I didn't understand the point of the input parameter for
> >> figuring out the output. The spec is written for someone who already
> >> knows what they're doing...
> >> 
> >> >
> >> > Cc: Rob Kramer <rob@solution-space.com>
> >> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=94825
> >> > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> >> > ---
> >> >  drivers/gpu/drm/i915/i915_drv.h       |  5 +++++
> >> >  drivers/gpu/drm/i915/intel_bios.c     | 13 ++++++++++---
> >> >  drivers/gpu/drm/i915/intel_opregion.c | 13 +++++++++++++
> >> >  3 files changed, 28 insertions(+), 3 deletions(-)
> >> >
> >> > diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> >> > index 53ace572b292..533263a7a12d 100644
> >> > --- a/drivers/gpu/drm/i915/i915_drv.h
> >> > +++ b/drivers/gpu/drm/i915/i915_drv.h
> >> > @@ -3421,6 +3421,7 @@ extern int intel_opregion_notify_encoder(struct intel_encoder *intel_encoder,
> >> >  					 bool enable);
> >> >  extern int intel_opregion_notify_adapter(struct drm_device *dev,
> >> >  					 pci_power_t state);
> >> > +extern int intel_opregion_get_panel_type(struct drm_device *dev);
> >> >  #else
> >> >  static inline int intel_opregion_setup(struct drm_device *dev) { return 0; }
> >> >  static inline void intel_opregion_init(struct drm_device *dev) { return; }
> >> > @@ -3436,6 +3437,10 @@ intel_opregion_notify_adapter(struct drm_device *dev, pci_power_t state)
> >> >  {
> >> >  	return 0;
> >> >  }
> >> > +static inline int intel_opregion_get_panel_type(struct drm_device *dev)
> >> > +{
> >> > +	return 0;
> >> > +}
> >> >  #endif
> >> >  
> >> >  /* intel_acpi.c */
> >> > diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c
> >> > index d9568be4b33b..718e49931b5f 100644
> >> > --- a/drivers/gpu/drm/i915/intel_bios.c
> >> > +++ b/drivers/gpu/drm/i915/intel_bios.c
> >> > @@ -205,16 +205,23 @@ parse_lfp_panel_data(struct drm_i915_private *dev_priv,
> >> >  	struct drm_display_mode *panel_fixed_mode;
> >> >  	int panel_type;
> >> >  	int drrs_mode;
> >> > +	int ret;
> >> >  
> >> >  	lvds_options = find_section(bdb, BDB_LVDS_OPTIONS);
> >> >  	if (!lvds_options)
> >> >  		return;
> >> >  
> >> >  	dev_priv->vbt.lvds_dither = lvds_options->pixel_dither;
> >> > -	if (lvds_options->panel_type > 0xf)
> >> > -		return;
> >> >  
> >> > -	panel_type = lvds_options->panel_type;
> >> > +	ret = intel_opregion_get_panel_type(dev_priv->dev);
> >> > +	if (ret >= 0x1 && ret <= 0xf) {
> >> 
> >> Undecided whether I'd like to have this check within
> >> intel_opregion_get_panel_type(). Just make that return 0 for "use vbt"
> >> (and CONFIG_ACPI=n), and valid stuff otherwise? *shrug*
> >
> > We don't compile intel_opregion.c when ACPI==n.
> 
> Yeah I meant the static inline stub in i915_drv.h for ACPI=n. Which does
> return 0.

I'm a bit lost here. Oh, maybe the ACPI=n note just confused me.
Did you just mean that I should do the 0x1-0xf check in
intel_opregion_get_panel_type() already?

> >> > +		panel_type = ret;
> >> > +	} else {
> >> > +		if (lvds_options->panel_type > 0xf)
> >> > +			return;
> >> > +		panel_type = lvds_options->panel_type;
> >> > +	}
> >> > +
> >> 
> >> If this actually works, I'd like to have some debug logging for pretty
> >> much all the code paths here.
> >
> > Yeah that would be nice for figuring out where the information came 
> > from or why it was rejected.
> >
> >> 
> >> Other than that, seems fine.
> >> 
> >> BR,
> >> Jani.
> >> 
> >> >  	dev_priv->vbt.panel_type = panel_type;
> >> >  
> >> >  	drrs_mode = (lvds_options->dps_panel_type_bits
> >> > diff --git a/drivers/gpu/drm/i915/intel_opregion.c b/drivers/gpu/drm/i915/intel_opregion.c
> >> > index c15718b4862a..5e17fa5dc869 100644
> >> > --- a/drivers/gpu/drm/i915/intel_opregion.c
> >> > +++ b/drivers/gpu/drm/i915/intel_opregion.c
> >> > @@ -1024,3 +1024,16 @@ err_out:
> >> >  	memunmap(base);
> >> >  	return err;
> >> >  }
> >> > +
> >> > +int
> >> > +intel_opregion_get_panel_type(struct drm_device *dev)
> >> > +{
> >> > +	u32 panel_details;
> >> > +	int ret;
> >> > +
> >> > +	ret = swsci(dev, SWSCI_GBDA_PANEL_DETAILS, 0x0, &panel_details);
> >> > +	if (ret)
> >> > +		return ret;
> >> > +
> >> > +	return (panel_details >> 8) & 0xff;
> >> > +}
> >> 
> >> -- 
> >> Jani Nikula, Intel Open Source Technology Center
> 
> -- 
> Jani Nikula, Intel Open Source Technology Center

-- 
Ville Syrjälä
Intel OTC
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