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Subject[PATCH 1/4] drm/sun4i: tcon: Support an active-low DE signal with RGB interface
Date
Some panels need an active-low data enable (DE) signal for the RGB
interface. This requires flipping a bit in the TCON0 polarity register
when setting up the mode for the RGB interface.

Add a new helper function to match specific bus flags and use it to set
the polarity inversion bit for the DE signal when required.

Signed-off-by: Paul Kocialkowski <contact@paulk.fr>
---
drivers/gpu/drm/sun4i/sun4i_tcon.c | 28 ++++++++++++++++++++++++++--
drivers/gpu/drm/sun4i/sun4i_tcon.h | 1 +
2 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c b/drivers/gpu/drm/sun4i/sun4i_tcon.c
index 3fb084f802e2..d249a462ec09 100644
--- a/drivers/gpu/drm/sun4i/sun4i_tcon.c
+++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c
@@ -78,6 +78,24 @@ static int sun4i_tcon_get_pixel_depth(const struct drm_encoder *encoder)
return -EINVAL;
}

+static bool sun4i_tcon_match_bus_flags(const struct drm_encoder *encoder,
+ u32 bus_flags)
+{
+ struct drm_connector *connector;
+ struct drm_display_info *info;
+
+ connector = sun4i_tcon_get_connector(encoder);
+ if (!connector)
+ return false;
+
+ info = &connector->display_info;
+
+ if ((info->bus_flags & bus_flags) == bus_flags)
+ return true;
+
+ return false;
+}
+
static void sun4i_tcon_channel_set_status(struct sun4i_tcon *tcon, int channel,
bool enabled)
{
@@ -415,6 +433,7 @@ static void sun4i_tcon0_mode_set_lvds(struct sun4i_tcon *tcon,
}

static void sun4i_tcon0_mode_set_rgb(struct sun4i_tcon *tcon,
+ const struct drm_encoder *encoder,
const struct drm_display_mode *mode)
{
unsigned int bp, hsync, vsync;
@@ -474,8 +493,13 @@ static void sun4i_tcon0_mode_set_rgb(struct sun4i_tcon *tcon,
if (mode->flags & DRM_MODE_FLAG_PVSYNC)
val |= SUN4I_TCON0_IO_POL_VSYNC_POSITIVE;

+ if (sun4i_tcon_match_bus_flags(encoder, DRM_BUS_FLAG_DE_LOW))
+ val |= SUN4I_TCON0_IO_POL_DE_NEGATIVE;
+
regmap_update_bits(tcon->regs, SUN4I_TCON0_IO_POL_REG,
- SUN4I_TCON0_IO_POL_HSYNC_POSITIVE | SUN4I_TCON0_IO_POL_VSYNC_POSITIVE,
+ SUN4I_TCON0_IO_POL_HSYNC_POSITIVE |
+ SUN4I_TCON0_IO_POL_VSYNC_POSITIVE |
+ SUN4I_TCON0_IO_POL_DE_NEGATIVE,
val);

/* Map output pins to channel 0 */
@@ -596,7 +620,7 @@ void sun4i_tcon_mode_set(struct sun4i_tcon *tcon,
sun4i_tcon0_mode_set_lvds(tcon, encoder, mode);
break;
case DRM_MODE_ENCODER_NONE:
- sun4i_tcon0_mode_set_rgb(tcon, mode);
+ sun4i_tcon0_mode_set_rgb(tcon, encoder, mode);
sun4i_tcon_set_mux(tcon, 0, encoder);
break;
case DRM_MODE_ENCODER_TVDAC:
diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.h b/drivers/gpu/drm/sun4i/sun4i_tcon.h
index f6a071cd5a6f..708399c80561 100644
--- a/drivers/gpu/drm/sun4i/sun4i_tcon.h
+++ b/drivers/gpu/drm/sun4i/sun4i_tcon.h
@@ -113,6 +113,7 @@

#define SUN4I_TCON0_IO_POL_REG 0x88
#define SUN4I_TCON0_IO_POL_DCLK_PHASE(phase) ((phase & 3) << 28)
+#define SUN4I_TCON0_IO_POL_DE_NEGATIVE BIT(27)
#define SUN4I_TCON0_IO_POL_HSYNC_POSITIVE BIT(25)
#define SUN4I_TCON0_IO_POL_VSYNC_POSITIVE BIT(24)

--
2.19.0
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