[Intel-gfx] [RFC v1 3/7] drm/i915: Add Support for Multi Segment Gamma Mode

Fri Mar 22 13:12:45 UTC 2019

>-----Original Message-----
>From: Roper, Matthew D
>Sent: Friday, March 22, 2019 3:23 AM
>To: Shankar, Uma <uma.shankar at intel.com>
>Cc: Syrjala, Ville <ville.syrjala at intel.com>; Lankhorst, Maarten
><maarten.lankhorst at intel.com>; intel-gfx at lists.freedesktop.org; Sharma, Shashank
><shashank.sharma at intel.com>
>Subject: Re: [RFC v1 3/7] drm/i915: Add Support for Multi Segment Gamma Mode
>
>On Wed, Mar 20, 2019 at 10:03:16AM -0700, Shankar, Uma wrote:
>>
>>
>> >-----Original Message-----
>> >From: Syrjala, Ville
>> >Sent: Tuesday, March 19, 2019 10:29 PM
>> >To: Lankhorst, Maarten <maarten.lankhorst at intel.com>
>> >Cc: Shankar, Uma <uma.shankar at intel.com>;
>> >intel-gfx at lists.freedesktop.org; Sharma, Shashank
>> ><shashank.sharma at intel.com>; Roper, Matthew D
>> ><matthew.d.roper at intel.com>
>> >Subject: Re: [RFC v1 3/7] drm/i915: Add Support for Multi Segment
>> >Gamma Mode
>> >
>> >On Tue, Mar 19, 2019 at 10:46:27AM +0200, Lankhorst, Maarten wrote:
>> >> tis 2019-03-19 klockan 14:00 +0530 skrev Uma Shankar:
>> >> > Multi Segment Gamma Mode is added in Gen11+ platforms.
>> >> > Added a property interface to enable that.
>> >> >
>> >> > Signed-off-by: Uma Shankar <uma.shankar at intel.com>
>> >> > ---
>> >> >  drivers/gpu/drm/i915/i915_drv.h    |  1 +
>> >> >  drivers/gpu/drm/i915/intel_color.c | 23 +++++++++++++++++++++++
>> >> >  include/uapi/drm/i915_drm.h        | 14 ++++++++++++++
>> >> >  3 files changed, 38 insertions(+)
>> >> >
>> >> > diff --git a/drivers/gpu/drm/i915/i915_drv.h
>> >> > b/drivers/gpu/drm/i915/i915_drv.h index 02231ae..f20d418 100644
>> >> > --- a/drivers/gpu/drm/i915/i915_drv.h
>> >> > +++ b/drivers/gpu/drm/i915/i915_drv.h
>> >> > @@ -1736,6 +1736,7 @@ struct drm_i915_private {
>> >> >  	struct drm_property *force_audio_property;
>> >> >
>> >> >  	struct drm_property *gamma_mode_property;
>> >> > +	struct drm_property *multi_segment_gamma_mode_property;
>> >>
>> >> Seems to me both properties should be part of drm core?
>>
>> Sure Maarten, we can move gamma_mode property to drm.
>>
>> >>
>> >> >  	/* hda/i915 audio component */
>> >> >  	struct i915_audio_component *audio_component; diff --git
>> >> > a/drivers/gpu/drm/i915/intel_color.c
>> >> > b/drivers/gpu/drm/i915/intel_color.c
>> >> > index 9d43d19..399d63d 100644
>> >> > --- a/drivers/gpu/drm/i915/intel_color.c
>> >> > +++ b/drivers/gpu/drm/i915/intel_color.c
>> >> > @@ -149,6 +149,26 @@ static bool crtc_state_is_legacy_gamma(const
>> >> > struct intel_crtc_state *crtc_state
>> >> >  	drm_object_attach_property(&crtc->base.base, prop, 0);  }
>> >> >
>> >> > +void
>> >> > +intel_attach_multi_segment_gamma_mode_property(struct intel_crtc
>> >> > *crtc)
>> >> > +{
>> >> > +	struct drm_device *dev = crtc->base.dev;
>> >> > +	struct drm_i915_private *dev_priv = to_i915(dev);
>> >> > +	struct drm_property *prop;
>> >> > +
>> >> > +	prop = dev_priv->multi_segment_gamma_mode_property;
>> >> > +	if (!prop) {
>> >> > +		prop = drm_property_create(dev, DRM_MODE_PROP_BLOB,
>> >> > +					   "Multi-segment Gamma",
>> >> > 0);
>> >> > +		if (!prop)
>> >> > +			return;
>> >> > +
>> >> > +		dev_priv->multi_segment_gamma_mode_property = prop;
>> >> > +	}
>> >> > +
>> >> > +	drm_object_attach_property(&crtc->base.base, prop, 0); }
>> >> > +
>> >> >  /*
>> >> >   * When using limited range, multiply the matrix given by
>> >> > userspace by
>> >> >   * the matrix that we would use for the limited range.
>> >> > @@ -953,4 +973,7 @@ void intel_color_init(struct intel_crtc *crtc)
>> >> >  					   INTEL_INFO(dev_priv)-
>> >> > >color.gamma_lut_size);
>> >> >
>> >> >  	intel_attach_gamma_mode_property(crtc);
>> >> > +
>> >> > +	if (INTEL_GEN(dev_priv) >= 11)
>> >> > +		intel_attach_multi_segment_gamma_mode_property(crtc)
>> >> > ;
>> >> >  }
>> >> > diff --git a/include/uapi/drm/i915_drm.h
>> >> > b/include/uapi/drm/i915_drm.h index aa2d4c7..8f1974e 100644
>> >> > --- a/include/uapi/drm/i915_drm.h
>> >> > +++ b/include/uapi/drm/i915_drm.h
>> >> > @@ -1842,6 +1842,20 @@ struct drm_i915_query_topology_info {
>> >> >  	__u8 data[];
>> >> >  };
>> >> >
>> >> > +/*
>> >> > + * Structure for muti segmented gamma lut  */ struct
>> >> > +multi_segment_gamma_lut {
>> >> > +	/* Number of Lut Segments */
>> >> > +	__u8 segment_cnt;
>> >> > +	/* Precison of LUT entries in bits */
>> >> > +	__u8 precision_bits;
>> >> > +	/* Pointer having number of LUT elements in each segment */
>> >> > +	__u32 *segment_lut_cnt_ptr;
>> >> > +	/* Pointer to store exact lut values for each segment */
>> >> > +	__u32 *segment_lut_ptr;
>
>I'm confused how this blob is supposed to be used.  It seems like the pointers in here
>won't be meaningful across the userspace/kernel copy?
>It also looks like 'segment_lut_ptr' doesn't appear again in this patch series.
>
>Like Ville describes below, I'd expect a property describing segmented gamma to
>basically be a collection of structures that describe a given range of the regular main
>LUT:  the start/end indices of the LUT that hold the segment, how the bits of table
>entries in this segment should be interpreted, etc.

Ok, will try to align to that approach and come up with the next version for this series.

>Whatever we come up with, it will definitely be important to add some kerneldoc that
>describes how the property is used/interpreted.

Sure, I will add detailed docs explaining the usage and expectation from userspace.

Thanks Matt for your comments.

Regards,
Uma Shankar

>
>
>Matt
>
>> >> > +};
>> >> >
>> >> And perhaps a variation of this as description for all gamma mode
>> >> types.
>> >
>> >This is my old idea how to represent fancier LUTs:
>> >https://github.com/vsyrjala/linux/commit/1aab7625dca77b831e05e32af179
>> >04c2130
>> >0ff95
>> >https://github.com/vsyrjala/linux/commit/74ffa5d441702c53830f6d71bb68
>> >7bb0ae5a
>> >a58f
>> >
>> >Each distinct segment of the curve would be just described by a fixed
>> >size range descriptor, and the entire blob would be made up of
>> >however many of those are needed.
>> >
>> >That way we don't even need any multi-segment uapi for setting up the
>> >LUT. The blob for that would just contain as many entries as the LUT needs in that
>specific mode.
>>
>> Hi Ville,
>> This also sounds good.  What is your suggestion on this. Any
>> recommendation on how to take this forward.
>>
>> Thanks & Regards,
>> Uma Shankar
>>
>> >--
>> >Ville Syrjälä
>> >Intel
>
>--
>Matt Roper
>Graphics Software Engineer
>IoTG Platform Enabling & Development
>Intel Corporation
>(916) 356-2795