[Intel-gfx] [PATCH 2/2] drm/i915/dsi: account for slower link in transcoder timings for DSC

[Jani Nikula]

FIXME: To be squashed to another patch.

Cc: Vandita Kulkarni <vandita.kulkarni at intel.com>
Signed-off-by: Jani Nikula <jani.nikula at intel.com>
---
 drivers/gpu/drm/i915/display/icl_dsi.c | 21 ++++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/icl_dsi.c b/drivers/gpu/drm/i915/display/icl_dsi.c
index f09e2e37d442..e343e476dbb5 100644
--- a/drivers/gpu/drm/i915/display/icl_dsi.c
+++ b/drivers/gpu/drm/i915/display/icl_dsi.c
@@ -799,11 +799,26 @@ gen11_dsi_set_transcoder_timings(struct intel_encoder *encoder,
 	u16 hback_porch;
 	/* vertical timings */
 	u16 vtotal, vactive, vsync_start, vsync_end, vsync_shift;
+	int cfr;
+
+	/*
+	 * Adjust horizontal timings (htotal, hsync_start, hsync_end) to account
+	 * for slower link speed if DSC is enabled.
+	 *
+	 * cfr for compression frequency ratio.
+	 *
+	 * FIXME: The clock sources are ugly.
+	 */
+	if (pipe_config->dsc.compression_enable)
+		cfr = DIV_ROUND_UP(100 * afe_clk(encoder, pipe_config),
+				   intel_dsi_bitrate(intel_dsi));
+	else
+		cfr = 100;
 
 	hactive = adjusted_mode->crtc_hdisplay;
-	htotal = adjusted_mode->crtc_htotal;
-	hsync_start = adjusted_mode->crtc_hsync_start;
-	hsync_end = adjusted_mode->crtc_hsync_end;
+	htotal = DIV_ROUND_UP(adjusted_mode->crtc_htotal * cfr, 100);
+	hsync_start = DIV_ROUND_UP(adjusted_mode->crtc_hsync_start * cfr, 100);
+	hsync_end = DIV_ROUND_UP(adjusted_mode->crtc_hsync_end * cfr, 100);
 	hsync_size  = hsync_end - hsync_start;
 	hback_porch = (adjusted_mode->crtc_htotal -
 		       adjusted_mode->crtc_hsync_end);
-- 
2.20.1