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drm/sun4i: tcon: set sync polarity for tcon1 channel 

Channel 1 has polarity bits for vsync and hsync signals but driver never
sets them. It turns out that with pre-HDMI2 controllers seemingly there
is no issue if polarity is not set. However, with HDMI2 controllers
(H6) there often comes to de-synchronization due to phase shift. This
causes flickering screen. It's safe to assume that similar issues might
happen also with pre-HDMI2 controllers.

Solve issue with setting vsync and hsync polarity. Note that display
stacks with tcon top have polarity bits actually in tcon0 polarity
register.

Fixes: 9026e0d122 ("drm: Add Allwinner A10 Display Engine support")
Reviewed-by: Chen-Yu Tsai <wens@csie.org>
Tested-by: Andre Heider <a.heider@gmail.com>
Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/20210209175900.7092-3-jernej.skrabec@siol.net
This commit is contained in:
Jernej Skrabec 2021-02-09 18:58:57 +01:00 committed by Maxime Ripard
parent 873e5bb9fb
commit 50791f5d7b
No known key found for this signature in database
GPG Key ID: E3EF0D6F671851C5
2 changed files with 31 additions and 0 deletions
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25
drivers/gpu/drm/sun4i/sun4i_tcon.c
View File

@ -689,6 +689,30 @@ static void sun4i_tcon1_mode_set(struct sun4i_tcon *tcon,
SUN4I_TCON1_BASIC5_V_SYNC(vsync) |
SUN4I_TCON1_BASIC5_H_SYNC(hsync));
/* Setup the polarity of multiple signals */
if (tcon->quirks->polarity_in_ch0) {
val = 0;
if (mode->flags & DRM_MODE_FLAG_PHSYNC)
val |= SUN4I_TCON0_IO_POL_HSYNC_POSITIVE;
if (mode->flags & DRM_MODE_FLAG_PVSYNC)
val |= SUN4I_TCON0_IO_POL_VSYNC_POSITIVE;
regmap_write(tcon->regs, SUN4I_TCON0_IO_POL_REG, val);
} else {
/* according to vendor driver, this bit must be always set */
val = SUN4I_TCON1_IO_POL_UNKNOWN;
if (mode->flags & DRM_MODE_FLAG_PHSYNC)
val |= SUN4I_TCON1_IO_POL_HSYNC_POSITIVE;
if (mode->flags & DRM_MODE_FLAG_PVSYNC)
val |= SUN4I_TCON1_IO_POL_VSYNC_POSITIVE;
regmap_write(tcon->regs, SUN4I_TCON1_IO_POL_REG, val);
}
/* Map output pins to channel 1 */
regmap_update_bits(tcon->regs, SUN4I_TCON_GCTL_REG,
SUN4I_TCON_GCTL_IOMAP_MASK,
@ -1517,6 +1541,7 @@ static const struct sun4i_tcon_quirks sun8i_a83t_tv_quirks = {
static const struct sun4i_tcon_quirks sun8i_r40_tv_quirks = {
.has_channel_1 = true,
.polarity_in_ch0 = true,
.set_mux = sun8i_r40_tcon_tv_set_mux,
};

6
drivers/gpu/drm/sun4i/sun4i_tcon.h
View File

@ -153,6 +153,11 @@
#define SUN4I_TCON1_BASIC5_V_SYNC(height) (((height) - 1) & 0x3ff)
#define SUN4I_TCON1_IO_POL_REG 0xf0
/* there is no documentation about this bit */
#define SUN4I_TCON1_IO_POL_UNKNOWN BIT(26)
#define SUN4I_TCON1_IO_POL_HSYNC_POSITIVE BIT(25)
#define SUN4I_TCON1_IO_POL_VSYNC_POSITIVE BIT(24)
#define SUN4I_TCON1_IO_TRI_REG 0xf4
#define SUN4I_TCON_ECC_FIFO_REG 0xf8
@ -235,6 +240,7 @@ struct sun4i_tcon_quirks {
bool needs_de_be_mux; /* sun6i needs mux to select backend */
bool needs_edp_reset; /* a80 edp reset needed for tcon0 access */
bool supports_lvds; /* Does the TCON support an LVDS output? */
bool polarity_in_ch0; /* some tcon1 channels have polarity bits in tcon0 pol register */
u8 dclk_min_div; /* minimum divider for TCON0 DCLK */
/* callback to handle tcon muxing options */