From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
Compute the increase in the DSI clock due to pixel overlap mode in
a way that's refresh rate agnostic. So far the computation assumed
a 60Hz refresh rate. And let's switch to round to closest here as
well since we would like to be as close to the target as possible.
Also toss in a decent comment explaining what we're actually doing
here.
Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/intel_dsi_panel_vbt.c | 17 ++++++++++++-----
1 file changed, 12 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_dsi_panel_vbt.c b/drivers/gpu/drm/i915/intel_dsi_panel_vbt.c
index 8f683b8b1816..3fd3bac5fccc 100644
--- a/drivers/gpu/drm/i915/intel_dsi_panel_vbt.c
+++ b/drivers/gpu/drm/i915/intel_dsi_panel_vbt.c
@@ -603,13 +603,20 @@ struct drm_panel *vbt_panel_init(struct intel_dsi *intel_dsi, u16 panel_id)
if (intel_dsi->dual_link) {
pclk = pclk / 2;
- /* we can enable pixel_overlap if needed by panel. In this
- * case we need to increase the pixelclock for extra pixels
+ /*
+ * In front-back mode the display is split vertically
+ * and the first half of pixels are transmitted by the
+ * first port, the second half by the second port. An
+ * overlapping strip of pixels is transmitted by both
+ * ports. The way this is specified is the number of
+ * pixels each half is extended horizontally (ie,
+ * pixel_overlap==1 actually means an overlap of two
+ * pixels). Thus we do this after the division by 2,
+ * otherwise we'd have to multiply the extra by two.
*/
if (intel_dsi->dual_link == DSI_DUAL_LINK_FRONT_BACK) {
- pclk += DIV_ROUND_UP(mode->vtotal *
- intel_dsi->pixel_overlap *
- 60, 1000);
+ pclk += DIV_ROUND_CLOSEST(intel_dsi->pixel_overlap *
+ mode->clock, mode->htotal);
}
}
--
2.7.4
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