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Subject[PATCH v4 06/11] drm/sun4i: tcon: multiply the vtotal when not in interlace
Date
It appears that the total vertical resolution needs to be doubled when
we're not in interlaced. Make sure that is the case.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
---
drivers/gpu/drm/sun4i/sun4i_tcon.c | 26 ++++++++++++++++++++++----
1 file changed, 22 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c b/drivers/gpu/drm/sun4i/sun4i_tcon.c
index 61e1de77831d..d9791292553e 100644
--- a/drivers/gpu/drm/sun4i/sun4i_tcon.c
+++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c
@@ -229,7 +229,7 @@ EXPORT_SYMBOL(sun4i_tcon0_mode_set);
void sun4i_tcon1_mode_set(struct sun4i_tcon *tcon,
struct drm_display_mode *mode)
{
- unsigned int bp, hsync, vsync;
+ unsigned int bp, hsync, vsync, vtotal;
u8 clk_delay;
u32 val;

@@ -276,12 +276,30 @@ void sun4i_tcon1_mode_set(struct sun4i_tcon *tcon,
SUN4I_TCON1_BASIC3_H_TOTAL(mode->crtc_htotal) |
SUN4I_TCON1_BASIC3_H_BACKPORCH(bp));

- /* Set vertical display timings */
bp = mode->crtc_vtotal - mode->crtc_vsync_start;
DRM_DEBUG_DRIVER("Setting vertical total %d, backporch %d\n",
- mode->vtotal, bp);
+ mode->crtc_vtotal, bp);
+
+ /*
+ * The vertical resolution needs to be doubled in all
+ * cases. We could use crtc_vtotal and always multiply by two,
+ * but that leads to a rounding error in interlace when vtotal
+ * is odd.
+ *
+ * This happens with TV's PAL for example, where vtotal will
+ * be 625, crtc_vtotal 312, and thus crtc_vtotal * 2 will be
+ * 624, which apparently confuses the hardware.
+ *
+ * To work around this, we will always use vtotal, and
+ * multiply by two only if we're not in interlace.
+ */
+ vtotal = mode->vtotal;
+ if (!(mode->flags & DRM_MODE_FLAG_INTERLACE))
+ vtotal = vtotal * 2;
+
+ /* Set vertical display timings */
regmap_write(tcon->regs, SUN4I_TCON1_BASIC4_REG,
- SUN4I_TCON1_BASIC4_V_TOTAL(mode->vtotal) |
+ SUN4I_TCON1_BASIC4_V_TOTAL(vtotal) |
SUN4I_TCON1_BASIC4_V_BACKPORCH(bp));

/* Set Hsync and Vsync length */
--
git-series 0.9.1
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