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

Ville Syrjälä
2016-04-08T14:59:17Z

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.

>
> > + 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

--
Ville Syrjälä
Intel OTC