[PATCH v3 1/3] drm/display/dp: Export fn to calculate link symbol cycles

[Arun R Murthy]

Unify the function to calculate the link symbol cycles for both dsc and
non-dsc case and export the function so that it can be used in the
respective platform display drivers for other calculations.

v2: unify the fn for both dsc and non-dsc case (Imre)
v3: rename drm_dp_link_symbol_cycles to drm_dp_link_data_symbol_cycles
    retain slice_eoc_cycles as is (Imre)

Signed-off-by: Arun R Murthy <arun.r.murthy at intel.com>
---
 drivers/gpu/drm/display/drm_dp_helper.c | 53 +++++++++++++++++----------------
 include/drm/display/drm_dp_helper.h     |  2 ++
 2 files changed, 29 insertions(+), 26 deletions(-)

diff --git a/drivers/gpu/drm/display/drm_dp_helper.c b/drivers/gpu/drm/display/drm_dp_helper.c
index 57828f2b7b5a0582ca4a6f2a9be2d5909fe8ad24..5ce8ccc3310fb71b39ea5f74c4022474c180f727 100644
--- a/drivers/gpu/drm/display/drm_dp_helper.c
+++ b/drivers/gpu/drm/display/drm_dp_helper.c
@@ -4392,26 +4392,33 @@ EXPORT_SYMBOL(drm_panel_dp_aux_backlight);
 
 #endif
 
-/* See DP Standard v2.1 2.6.4.4.1.1, 2.8.4.4, 2.8.7 */
-static int drm_dp_link_symbol_cycles(int lane_count, int pixels, int bpp_x16,
-				     int symbol_size, bool is_mst)
-{
-	int cycles = DIV_ROUND_UP(pixels * bpp_x16, 16 * symbol_size * lane_count);
-	int align = is_mst ? 4 / lane_count : 1;
-
-	return ALIGN(cycles, align);
-}
-
-static int drm_dp_link_dsc_symbol_cycles(int lane_count, int pixels, int slice_count,
-					 int bpp_x16, int symbol_size, bool is_mst)
-{
-	int slice_pixels = DIV_ROUND_UP(pixels, slice_count);
-	int slice_data_cycles = drm_dp_link_symbol_cycles(lane_count, slice_pixels,
-							  bpp_x16, symbol_size, is_mst);
+/**
+ * drm_dp_link_data_symbol_cycles - calculate the link symbol count
+ * @lane_coount: DP link lane count
+ * @pixels: horizontal active pixels
+ * @bpp_x16: bits per pixel in .4 binary fixed format
+ * @symbol_size: DP symbol size
+ * @is_mst: is mst or sst
+ * @slice_count: number of slices
+ *
+ * Calculate the link symbol cycles for both dsc and non dsc case and
+ * return the count.
+ */
+int drm_dp_link_data_symbol_cycles(int lane_count, int pixels, int bpp_x16,
+				   int symbol_size, bool is_mst, int slice_count)
+{
+	int slice_pixels = slice_count ? DIV_ROUND_UP(pixels, slice_count) :
+					 pixels;
+	int cycles = DIV_ROUND_UP(slice_pixels * bpp_x16,
+				  (6 * symbol_size * lane_count));
+	int slice_data_cycles = ALIGN(cycles, is_mst ? (4 / lane_count) : 1);
 	int slice_eoc_cycles = is_mst ? 4 / lane_count : 1;
 
-	return slice_count * (slice_data_cycles + slice_eoc_cycles);
+	return slice_count ? (slice_count *
+			      (slice_data_cycles + slice_eoc_cycles)) :
+			      slice_data_cycles;
 }
+EXPORT_SYMBOL(drm_dp_link_data_symbol_cycles);
 
 /**
  * drm_dp_bw_overhead - Calculate the BW overhead of a DP link stream
@@ -4486,15 +4493,9 @@ int drm_dp_bw_overhead(int lane_count, int hactive,
 	WARN_ON((flags & DRM_DP_BW_OVERHEAD_UHBR) &&
 		(flags & DRM_DP_BW_OVERHEAD_FEC));
 
-	if (flags & DRM_DP_BW_OVERHEAD_DSC)
-		symbol_cycles = drm_dp_link_dsc_symbol_cycles(lane_count, hactive,
-							      dsc_slice_count,
-							      bpp_x16, symbol_size,
-							      is_mst);
-	else
-		symbol_cycles = drm_dp_link_symbol_cycles(lane_count, hactive,
-							  bpp_x16, symbol_size,
-							  is_mst);
+	symbol_cycles = drm_dp_link_data_symbol_cycles(lane_count, hactive,
+						       bpp_x16, symbol_size,
+						       is_mst, dsc_slice_count);
 
 	return DIV_ROUND_UP_ULL(mul_u32_u32(symbol_cycles * symbol_size * lane_count,
 					    overhead * 16),
diff --git a/include/drm/display/drm_dp_helper.h b/include/drm/display/drm_dp_helper.h
index d9614e2c89397536f44bb7258e894628ae1dccc9..98bbbe98e5bc0ce0f9cdf513b2c5ea90bb5caffb 100644
--- a/include/drm/display/drm_dp_helper.h
+++ b/include/drm/display/drm_dp_helper.h
@@ -971,5 +971,7 @@ int drm_dp_bw_channel_coding_efficiency(bool is_uhbr);
 int drm_dp_max_dprx_data_rate(int max_link_rate, int max_lanes);
 
 ssize_t drm_dp_vsc_sdp_pack(const struct drm_dp_vsc_sdp *vsc, struct dp_sdp *sdp);
+int drm_dp_link_data_symbol_cycles(int lane_count, int pixels, int bpp_x16,
+				   int symbol_size, bool is_mst, int slice_count);
 
 #endif /* _DRM_DP_HELPER_H_ */

-- 
2.25.1