[PATCH v2 7/9] drm/sun4i: dsi: Rework a bit the hblk calculation

[Maxime Ripard]

It turns out that the hblk calculation actually follows a similar pattern
than the other packets. Rework a bit the calculation and add a comment.

Signed-off-by: Maxime Ripard <maxime.ripard at bootlin.com>
---
 drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
index 8e6392831e9d..e0288e7dc64e 100644
--- a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
+++ b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
@@ -488,9 +488,13 @@ static void sun6i_dsi_setup_timings(struct sun6i_dsi *dsi,
 		  (mode->hsync_start - mode->hdisplay) * Bpp - HFP_PACKET_OVERHEAD);
 
 	/*
-	 * hblk seems to be the line + porches length.
+	 * The blanking is set using a sync event (4 bytes) and a
+	 * blanking packet (4 bytes + payload + 2 bytes). Its minimal
+	 * size is therefore 10 bytes.
 	 */
-	hblk = mode->htotal * Bpp - hsa;
+#define HBLK_PACKET_OVERHEAD	10
+	hblk = max((unsigned int)HBLK_PACKET_OVERHEAD,
+		   (mode->htotal - (mode->hsync_end - mode->hsync_start)) * Bpp - HBLK_PACKET_OVERHEAD);
 
 	/*
 	 * And I'm not entirely sure what vblk is about. The driver in
-- 
git-series 0.9.1