[02/10] drm/i915/dp: Limit max link bpp properly to a fractional value on SST

Commit Message

Imre Deak April 8, 2025, 9:43 p.m. UTC

The maximum link bpp - determined by the link BW for instance - can be
fractional, handle this properly during computing the link bpp on SST.

This keeps the pipe joiner specific maximum link bpp as a rounded-down
integer value still, changing that to a fractional value is left for
later.

Signed-off-by: Imre Deak <[e-mail]>
---
 drivers/gpu/drm/i915/display/intel_dp.c | 15 ++++-----------
 1 file changed, 4 insertions(+), 11 deletions(-)

Patch

diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 713cc6e65faac..14c3d5e10a430 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -938,6 +938,7 @@  static u32 ultrajoiner_ram_max_bpp(u32 mode_hdisplay)
 	return ultrajoiner_ram_bits() / mode_hdisplay;
 }
 
+/* TODO: return a bpp_x16 value */
 static
 u32 get_max_compressed_bpp_with_joiner(struct intel_display *display,
 				       u32 mode_clock, u32 mode_hdisplay,
@@ -2148,24 +2149,16 @@  static int dsc_compute_compressed_bpp(struct intel_dp *intel_dp,
 	const struct intel_connector *connector = to_intel_connector(conn_state->connector);
 	const struct drm_display_mode *adjusted_mode = &pipe_config->hw.adjusted_mode;
 	int output_bpp;
-	int dsc_min_bpp;
-	int dsc_max_bpp;
-	int min_bpp_x16, max_bpp_x16, bpp_step_x16;
+	int max_bpp_x16, bpp_step_x16;
 	int dsc_joiner_max_bpp;
 	int num_joined_pipes = intel_crtc_num_joined_pipes(pipe_config);
 	int bpp_x16;
 	int ret;
 
-	dsc_min_bpp = fxp_q4_to_int_roundup(limits->link.min_bpp_x16);
-
 	dsc_joiner_max_bpp = get_max_compressed_bpp_with_joiner(display, adjusted_mode->clock,
 								adjusted_mode->hdisplay,
 								num_joined_pipes);
-	dsc_max_bpp = min(dsc_joiner_max_bpp, fxp_q4_to_int(limits->link.max_bpp_x16));
-
-	/* FIXME: remove the round trip via integers */
-	min_bpp_x16 = fxp_q4_from_int(dsc_min_bpp);
-	max_bpp_x16 = fxp_q4_from_int(dsc_max_bpp);
+	max_bpp_x16 = min(fxp_q4_from_int(dsc_joiner_max_bpp), limits->link.max_bpp_x16);
 
 	bpp_step_x16 = intel_dp_dsc_bpp_step_x16(connector);
 
@@ -2173,7 +2166,7 @@  static int dsc_compute_compressed_bpp(struct intel_dp *intel_dp,
 	output_bpp = intel_dp_output_bpp(pipe_config->output_format, pipe_bpp);
 	max_bpp_x16 = min(max_bpp_x16, fxp_q4_from_int(output_bpp) - bpp_step_x16);
 
-	for (bpp_x16 = max_bpp_x16; bpp_x16 >= min_bpp_x16; bpp_x16 -= bpp_step_x16) {
+	for (bpp_x16 = max_bpp_x16; bpp_x16 >= limits->link.min_bpp_x16; bpp_x16 -= bpp_step_x16) {
 		if (!intel_dp_dsc_valid_bpp(intel_dp, bpp_x16))
 			continue;