Re: [v7, 01/16] drm: Add Enhanced Gamma LUT precision structure

["james qian wang (Arm Technology China)" <james.qian.wang@arm.com>]

On Wed, Aug 14, 2019 at 02:29:57PM +0000, Shankar, Uma wrote:
> 
> 
> >-----Original Message-----
> >From: james qian wang (Arm Technology China) [mailto:james.qian.wang@arm.com]
> >Sent: Tuesday, August 13, 2019 3:12 PM
> >To: Shankar, Uma <uma.shankar@intel.com>
> >Cc: intel-gfx@lists.freedesktop.org; dri-devel@lists.freedesktop.org; Syrjala, Ville
> ><ville.syrjala@intel.com>; emil.l.velikov@gmail.com; Lankhorst, Maarten
> ><maarten.lankhorst@intel.com>; nd <nd@arm.com>
> >Subject: Re: [v7,01/16] drm: Add Enhanced Gamma LUT precision structure
> >
> >On Fri, Mar 29, 2019 at 01:45:59AM +0530, Uma Shankar wrote:
> >> Existing LUT precision structure is having only 16 bit precision. This
> >> is not enough for upcoming enhanced hardwares and advance usecases
> >> like HDR processing. Hence added a new structure with 32 bit precision
> >> values. Also added the code, for extracting the same from values
> >> passed from userspace.
> >>
> >> v4: Rebase
> >>
> >> v5: Relocated the helper function to drm_color_mgmt.c. Declared the
> >> same in a header file (Alexandru Gheorghe)
> >>
> >> v6: Enhanced gamma lut structure to take U32.32 format as input.
> >> This is needed for HDR usecase which require higher precision.
> >>
> >> v7: Addressed Maarten's review comments and fixed the calculation.
> >>
> >> Signed-off-by: Uma Shankar <uma.shankar@intel.com>
> >> Reviewed-by: Alexandru Gheorghe <alexandru-cosmin.gheorghe@arm.com>
> >
> >Hi Uma
> >
> >When can we merge these plane color-mgmt support into upstream ?
> >or can we merge the DRM-CORE part patches firstly?
> 
> Hi James,
> I will refresh this series by early next week. We will try to prioritize this development and speed
> up with merge.

> Regards,
> Uma Shankar

hi Uma:
thank you very much

Best Regards,
James

> >thanks
> >james
> >
> >> ---
> >>  drivers/gpu/drm/drm_color_mgmt.c | 20 ++++++++++++++++++++
> >>  include/drm/drm_color_mgmt.h     |  1 +
> >>  include/uapi/drm/drm_mode.h      | 15 +++++++++++++++
> >>  3 files changed, 36 insertions(+)
> >>
> >> diff --git a/drivers/gpu/drm/drm_color_mgmt.c
> >> b/drivers/gpu/drm/drm_color_mgmt.c
> >> index d5d34d0..79ff874 100644
> >> --- a/drivers/gpu/drm/drm_color_mgmt.c
> >> +++ b/drivers/gpu/drm/drm_color_mgmt.c
> >> @@ -128,6 +128,26 @@ uint32_t drm_color_lut_extract(uint32_t
> >> user_input, uint32_t bit_precision)  }
> >> EXPORT_SYMBOL(drm_color_lut_extract);
> >>
> >> +/*
> >> + * Added to accommodate enhanced LUT precision.
> >> + * Max LUT precision is 32 bits.
> >> + */
> >> +u64 drm_color_lut_extract_ext(u64 user_input, u32 bit_precision) {
> >> +	u64 val = user_input & 0xffffffff;
> >> +	u32 max = 0xffffffff >> (32 - bit_precision);
> >> +
> >> +	/* Round only if we're not using full precision. */
> >> +	if (bit_precision < 32) {
> >> +		val += 1UL << (32 - bit_precision - 1);
> >> +		val >>= 32 - bit_precision;
> >> +	}
> >> +
> >> +	return ((user_input & 0xffffffff00000000) |
> >> +		clamp_val(val, 0, max));
> >> +}
> >> +EXPORT_SYMBOL(drm_color_lut_extract_ext);
> >> +
> >>  /**
> >>   * drm_crtc_enable_color_mgmt - enable color management properties
> >>   * @crtc: DRM CRTC
> >> diff --git a/include/drm/drm_color_mgmt.h
> >> b/include/drm/drm_color_mgmt.h index d1c662d..c9d2746 100644
> >> --- a/include/drm/drm_color_mgmt.h
> >> +++ b/include/drm/drm_color_mgmt.h
> >> @@ -30,6 +30,7 @@
> >>  struct drm_plane;
> >>
> >>  uint32_t drm_color_lut_extract(uint32_t user_input, uint32_t
> >> bit_precision);
> >> +u64 drm_color_lut_extract_ext(u64 user_input, u32 bit_precision);
> >>
> >>  void drm_crtc_enable_color_mgmt(struct drm_crtc *crtc,
> >>  				uint degamma_lut_size,
> >> diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h
> >> index 09d7296..ca81410 100644
> >> --- a/include/uapi/drm/drm_mode.h
> >> +++ b/include/uapi/drm/drm_mode.h
> >> @@ -629,6 +629,21 @@ struct drm_color_lut {
> >>  	__u16 reserved;
> >>  };
> >>
> >> +/*
> >> + * Creating 64 bit palette entries for better data
> >> + * precision. This will be required for HDR and
> >> + * similar color processing usecases.
> >> + */
> >> +struct drm_color_lut_ext {
> >> +	/*
> >> +	 * Data is U32.32 fixed point format.
> >> +	 */
> >> +	__u64 red;
> >> +	__u64 green;
> >> +	__u64 blue;
> >> +	__u64 reserved;
> >> +};
> >> +
> >>  #define DRM_MODE_PAGE_FLIP_EVENT 0x01  #define
> >> DRM_MODE_PAGE_FLIP_ASYNC 0x02  #define
> >> DRM_MODE_PAGE_FLIP_TARGET_ABSOLUTE 0x4
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