[RESEND 1/2] drm/i915/dsc: Use helper to calculate range_bpg_offset

[Ankit Nautiyal <ankit.k.nautiyal@intel.com>]

We get range_bpg_offset for different bpps based on
linear-interpolation from values given for nearby bpps.
Use a helper to get these values.

Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Reviewed-by: Suraj Kandpal <suraj.kandpal@intel.com>
---
 drivers/gpu/drm/i915/display/intel_vdsc.c | 59 ++++++++++++-----------
 1 file changed, 30 insertions(+), 29 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_vdsc.c b/drivers/gpu/drm/i915/display/intel_vdsc.c
index b355c479eda3..df07090c84eb 100644
--- a/drivers/gpu/drm/i915/display/intel_vdsc.c
+++ b/drivers/gpu/drm/i915/display/intel_vdsc.c
@@ -66,6 +66,13 @@ intel_vdsc_set_min_max_qp(struct drm_dsc_config *vdsc_cfg, int buf,
 		intel_lookup_range_max_qp(bpc, buf, bpp, vdsc_cfg->native_420);
 }
 
+static int
+get_range_bpg_offset(int bpp_low, int offset_low, int bpp_high, int offset_high, int bpp)
+{
+	return offset_low + DIV_ROUND_UP((offset_high - offset_low) * (bpp - bpp_low),
+					 (bpp_low - bpp_high));
+}
+
 /*
  * We are using the method provided in DSC 1.2a C-Model in codec_main.c
  * Above method use a common formula to derive values for any combination of DSC
@@ -83,7 +90,7 @@ calculate_rc_params(struct drm_dsc_config *vdsc_cfg)
 	int qp_bpc_modifier = (bpc - 8) * 2;
 	int uncompressed_bpg_rate;
 	int first_line_bpg_offset;
-	u32 res, buf_i, bpp_i;
+	u32 buf_i, bpp_i;
 
 	if (vdsc_cfg->slice_height >= 8)
 		first_line_bpg_offset =
@@ -163,23 +170,19 @@ calculate_rc_params(struct drm_dsc_config *vdsc_cfg)
 			intel_vdsc_set_min_max_qp(vdsc_cfg, buf_i, bpp_i);
 
 			/* Calculate range_bpg_offset */
-			if (bpp <= 8) {
+			if (bpp <= 8)
 				range_bpg_offset = ofs_und4[buf_i];
-			} else if (bpp <= 10) {
-				res = DIV_ROUND_UP(((bpp - 8) *
-						    (ofs_und5[buf_i] - ofs_und4[buf_i])), 2);
-				range_bpg_offset = ofs_und4[buf_i] + res;
-			} else if (bpp <= 12) {
-				res = DIV_ROUND_UP(((bpp - 10) *
-						    (ofs_und6[buf_i] - ofs_und5[buf_i])), 2);
-				range_bpg_offset = ofs_und5[buf_i] + res;
-			} else if (bpp <= 16) {
-				res = DIV_ROUND_UP(((bpp - 12) *
-						    (ofs_und8[buf_i] - ofs_und6[buf_i])), 4);
-				range_bpg_offset = ofs_und6[buf_i] + res;
-			} else {
+			else if (bpp <= 10)
+				range_bpg_offset = get_range_bpg_offset(8, ofs_und4[buf_i],
+									10, ofs_und5[buf_i], bpp);
+			else if (bpp <= 12)
+				range_bpg_offset = get_range_bpg_offset(10, ofs_und5[buf_i],
+									12, ofs_und6[buf_i], bpp);
+			else if (bpp <= 16)
+				range_bpg_offset = get_range_bpg_offset(12, ofs_und6[buf_i],
+									16, ofs_und8[buf_i], bpp);
+			else
 				range_bpg_offset = ofs_und8[buf_i];
-			}
 
 			vdsc_cfg->rc_range_params[buf_i].range_bpg_offset =
 				range_bpg_offset & DSC_RANGE_BPG_OFFSET_MASK;
@@ -215,21 +218,19 @@ calculate_rc_params(struct drm_dsc_config *vdsc_cfg)
 			intel_vdsc_set_min_max_qp(vdsc_cfg, buf_i, bpp_i);
 
 			/* Calculate range_bpg_offset */
-			if (bpp <= 6) {
+			if (bpp <= 6)
 				range_bpg_offset = ofs_und6[buf_i];
-			} else if (bpp <= 8) {
-				res = DIV_ROUND_UP(((bpp - 6) *
-						    (ofs_und8[buf_i] - ofs_und6[buf_i])), 2);
-				range_bpg_offset = ofs_und6[buf_i] + res;
-			} else if (bpp <= 12) {
-				range_bpg_offset = ofs_und8[buf_i];
-			} else if (bpp <= 15) {
-				res = DIV_ROUND_UP(((bpp - 12) *
-						    (ofs_und15[buf_i] - ofs_und12[buf_i])), 3);
-				range_bpg_offset = ofs_und12[buf_i] + res;
-			} else {
+			else if (bpp <= 8)
+				range_bpg_offset = get_range_bpg_offset(6, ofs_und6[buf_i],
+									8, ofs_und8[buf_i], bpp);
+			else if (bpp <= 12)
+				range_bpg_offset = get_range_bpg_offset(8, ofs_und8[buf_i],
+									12, ofs_und12[buf_i], bpp);
+			else if (bpp <= 15)
+				range_bpg_offset = get_range_bpg_offset(12, ofs_und12[buf_i],
+									15, ofs_und15[buf_i], bpp);
+			else
 				range_bpg_offset = ofs_und15[buf_i];
-			}
 
 			vdsc_cfg->rc_range_params[buf_i].range_bpg_offset =
 				range_bpg_offset & DSC_RANGE_BPG_OFFSET_MASK;
-- 
2.45.2