drm/i915/dsc: Define & Compute VESA DSC params

This patches does the following:

1. This patch defines all the DSC parameters as per the VESA
DSC specification. These are stored in the encoder and used
to compute the PPS parameters to be sent to the Sink.
2. Compute all the DSC parameters which are derived from DSC
state of intel_crtc_state.
3. Compute all parameters that are VESA DSC specific

This computation happens in the atomic check phase during
compute_config() to validate if display stream compression
can be enabled for the requested mode.

v8 (From Manasi):
* DEBUG_KMS instead of DRM_ERROR for user triggerable
errors (Ville)
v7: (From Manasi)
* Dont use signed int for rc_range_params (Manasi)
* Mask the range_bpg_offset to use only 6 bits
* Add SPDX identifier (Chris Wilson)
v6 (From Manasi):
* Add a check for line_buf_depth return value (Anusha)
* Remove DRM DSC constants to different patch (Manasi)
v5 (From Manasi):
* Add logic to limit the max line buf depth for DSC 1.1 to 13
as per DSC 1.1 spec
* Fix dim checkpatch warnings/checks

v4 (From Gaurav):
* Rebase on latest drm tip
* rename variable name(Manasi)
* Populate linebuf_depth variable(Manasi)

v3 (From Gaurav):
* Rebase my previous patches on top of Manasi's latest patch
series
* Using >>n rather than /2^n (Manasi)
* Change the commit message to explain what the patch is doing(Gaurav)

Fixed review comments from Ville:
* Don't use macro TWOS_COMPLEMENT
* Mention in comment about the source of RC params
* Return directly from case statements
* Using single asssignment for assigning rc_range_params
* Using <<n rather than *2^n and removing the comments
about the fixed point numbers

v2 (From Manasi):
* Update logic for minor version to consider the dpcd value
and what supported by the HW platform
* Use DRM DSC config struct instead of intel_dp struct
* Move the DSC constants to DRM DSC header file
* Use u16, u8 where bigger data types not needed
* * Compute the DSC parameters as part of DSC compute config
since the computation can fail (Manasi)

Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
Cc: Anusha Srivatsa <anusha.srivatsa@intel.com>
Cc: Gaurav K Singh <gaurav.k.singh@intel.com>
Signed-off-by: Gaurav K Singh <gaurav.k.singh@intel.com>
Signed-off-by: Manasi Navare <manasi.d.navare@intel.com>
Co-developed-by: Manasi Navare <manasi.d.navare@intel.com>
Reviewed-by: Anusha Srivatsa <anusha.srivatsa@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181129193827.7914-1-manasi.d.navare@intel.com

drivers/gpu/drm/i915/intel_drv.h

@@ -1857,6 +1857,10 @@ uint16_t intel_dp_dsc_get_output_bpp(int link_clock, uint8_t lane_count,
 uint8_t intel_dp_dsc_get_slice_count(struct intel_dp *intel_dp, int mode_clock,
 				     int mode_hdisplay);
 
+/* intel_vdsc.c */
+int intel_dp_compute_dsc_params(struct intel_dp *intel_dp,
+				struct intel_crtc_state *pipe_config);
+
 static inline unsigned int intel_dp_unused_lane_mask(int lane_count)
 {
 	return ~((1 << lane_count) - 1) & 0xf;