[PATCH v2 1/8] drm/i915/hdmi: Split the intel_hdmi_dsc_get_bpp()

Split the intel_hdmi_dsc_get_bpp() into two helper functions
that can be called independently.

While at it, improve the comments in the helper.

Signed-off-by: Ankit Nautiyal <[email protected]>
---
 drivers/gpu/drm/i915/display/intel_hdmi.c | 97 ++++++++++++++---------
 1 file changed, 59 insertions(+), 38 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_hdmi.c b/drivers/gpu/drm/i915/display/intel_hdmi.c
index 9b637e38a1a5..df88d7c141f7 100644
--- a/drivers/gpu/drm/i915/display/intel_hdmi.c
+++ b/drivers/gpu/drm/i915/display/intel_hdmi.c
@@ -3325,61 +3325,49 @@ intel_hdmi_dsc_get_num_slices(const struct drm_display_mode *mode,
 	return target_slices;
 }
 
-/*
- * intel_hdmi_dsc_get_bpp - get the appropriate compressed bits_per_pixel based on
- * source and sink capabilities.
- *
- * @src_fraction_bpp: fractional bpp supported by the source
- * @slice_width: dsc slice width supported by the source and sink
- * @num_slices: num of slices supported by the source and sink
- * @output_format: video output format
- * @bpc: bits per color
- * @hdmi_all_bpp: sink supports decoding of 1/16th bpp setting
- * @hdmi_max_chunk_bytes: max bytes in a line of chunks supported by sink
- *
- * @return: compressed bits_per_pixel in step of 1/16 of bits_per_pixel
- */
-int
-intel_hdmi_dsc_get_bpp(int src_fractional_bpp, int slice_width, int num_slices,
-		       enum intel_output_format output_format, int bpc,
-		       bool hdmi_all_bpp, int hdmi_max_chunk_bytes)
+static void
+get_dsc_min_max_bpp(enum intel_output_format output_format, u8 bpc,
+		    bool hdmi_all_bpp, int *min_dsc_bpp, int *max_dsc_bpp)
 {
-	int max_dsc_bpp, min_dsc_bpp;
-	int target_bytes;
-	bool bpp_found = false;
-	int bpp_decrement_x16;
-	int bpp_target;
-	int bpp_target_x16;
-
 	/*
-	 * Get min bpp and max bpp as per Table 7.23, in HDMI2.1 spec
+	 * Get min bpp and max bpp that can be supported for a
+	 * given bpc and output format.
 	 * Start with the max bpp and keep on decrementing with
-	 * fractional bpp, if supported by PCON DSC encoder
+	 * fractional bpp, if supported by the DSC encoder
 	 *
 	 * for each bpp we check if no of bytes can be supported by HDMI sink
 	 */
 
 	if (output_format == INTEL_OUTPUT_FORMAT_YCBCR420) {
-		min_dsc_bpp = 6;
-		max_dsc_bpp = 3 * bpc / 2;
+		*min_dsc_bpp = 6;
+		*max_dsc_bpp = 3 * bpc / 2;
 	} else if (output_format == INTEL_OUTPUT_FORMAT_YCBCR444 ||
 		   output_format == INTEL_OUTPUT_FORMAT_RGB) {
-		min_dsc_bpp = 8;
-		max_dsc_bpp = 3 * bpc;
+		*min_dsc_bpp = 8;
+		*max_dsc_bpp = 3 * bpc;
 	} else {
 		/* Assuming 4:2:2 encoding */
-		min_dsc_bpp = 7;
-		max_dsc_bpp = 2 * bpc;
+		*min_dsc_bpp = 7;
+		*max_dsc_bpp = 2 * bpc;
 	}
 
 	/*
-	 * Taking into account if all dsc_all_bpp supported by HDMI2.1 sink
-	 * Section 7.7.34 : Source shall not enable compressed Video
-	 * Transport with bpp_target settings above 12 bpp unless
-	 * DSC_all_bpp is set to 1.
+	 * Don't enable DSC bpp_target settings above 12 bpp,
+	 * unless DSC_all_bpp is set to 1.
 	 */
 	if (!hdmi_all_bpp)
-		max_dsc_bpp = min(max_dsc_bpp, 12);
+		*max_dsc_bpp = min(*max_dsc_bpp, 12);
+}
+
+static int
+get_dsc_compressed_bpp(int num_slices, int slice_width, int hdmi_max_chunk_bytes,
+		       int src_fractional_bpp, int min_dsc_bpp, int max_dsc_bpp)
+{
+	int target_bytes;
+	bool bpp_found = false;
+	int bpp_decrement_x16;
+	int bpp_target;
+	int bpp_target_x16;
 
 	/*
 	 * The Sink has a limit of compressed data in bytes for a scanline,
@@ -3423,6 +3411,39 @@ intel_hdmi_dsc_get_bpp(int src_fractional_bpp, int slice_width, int num_slices,
 	return 0;
 }
 
+/*
+ * intel_hdmi_dsc_get_bpp - get the appropriate compressed bits_per_pixel based on
+ * source and sink capabilities.
+ *
+ * @src_fraction_bpp: fractional bpp supported by the source
+ * @slice_width: dsc slice width supported by the source and sink
+ * @num_slices: num of slices supported by the source and sink
+ * @output_format: video output format
+ * @bpc: bits per color
+ * @hdmi_all_bpp: sink supports decoding of 1/16th bpp setting
+ * @hdmi_max_chunk_bytes: max bytes in a line of chunks supported by sink
+ *
+ * @return: compressed bits_per_pixel in step of 1/16 of bits_per_pixel
+ */
+int
+intel_hdmi_dsc_get_bpp(int src_fractional_bpp, int slice_width, int num_slices,
+		       enum intel_output_format output_format, int bpc,
+		       bool hdmi_all_bpp, int hdmi_max_chunk_bytes)
+{
+	int max_dsc_bpp, min_dsc_bpp;
+	int dsc_bpp_x16;
+
+	get_dsc_min_max_bpp(output_format, bpc, hdmi_all_bpp,
+			    &min_dsc_bpp, &max_dsc_bpp);
+
+	dsc_bpp_x16 = get_dsc_compressed_bpp(num_slices, slice_width,
+					     hdmi_max_chunk_bytes,
+					     src_fractional_bpp,
+					     min_dsc_bpp, max_dsc_bpp);
+
+	return dsc_bpp_x16;
+}
+
 int intel_hdmi_sink_max_frl_rate(struct drm_connector *connector)
 {
 	int max_lanes = connector->display_info.hdmi.max_lanes;
-- 
2.50.1