drm/sun4i: tcon: Support backend input mux
The TCON has a mux to select the source of the data to display.
This mux includes selecting the display backends. On the A31,
which has two display pipelines, this mux can let the TCON
select either backend as its data source. Although the muxing
can be changed on the fly, DRM needs to be able to group a
bunch of layers such that they get switched to another crtc
together. This is because the display backend does the layer
compositing, while the TCON generates the display timings.
This constraint is not supported by DRM.
Here we simply pair up backends and TCONs with the same ID.
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20170908075016.18657-7-wens@csie.org
diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c b/drivers/gpu/drm/sun4i/sun4i_tcon.c
index fb42e57..e853dfe5 100644
--- a/drivers/gpu/drm/sun4i/sun4i_tcon.c
+++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c
@@ -699,6 +699,25 @@ static int sun4i_tcon_bind(struct device *dev, struct device *master,
if (ret < 0)
goto err_free_clocks;
+ if (tcon->quirks->needs_de_be_mux) {
+ /*
+ * We assume there is no dynamic muxing of backends
+ * and TCONs, so we select the backend with same ID.
+ *
+ * While dynamic selection might be interesting, since
+ * the CRTC is tied to the TCON, while the layers are
+ * tied to the backends, this means, we will need to
+ * switch between groups of layers. There might not be
+ * a way to represent this constraint in DRM.
+ */
+ regmap_update_bits(tcon->regs, SUN4I_TCON0_CTL_REG,
+ SUN4I_TCON0_CTL_SRC_SEL_MASK,
+ tcon->id);
+ regmap_update_bits(tcon->regs, SUN4I_TCON1_CTL_REG,
+ SUN4I_TCON1_CTL_SRC_SEL_MASK,
+ tcon->id);
+ }
+
list_add_tail(&tcon->list, &drv->tcon_list);
return 0;
@@ -754,11 +773,13 @@ static const struct sun4i_tcon_quirks sun5i_a13_quirks = {
};
static const struct sun4i_tcon_quirks sun6i_a31_quirks = {
- .has_channel_1 = true,
+ .has_channel_1 = true,
+ .needs_de_be_mux = true,
};
static const struct sun4i_tcon_quirks sun6i_a31s_quirks = {
- .has_channel_1 = true,
+ .has_channel_1 = true,
+ .needs_de_be_mux = true,
};
static const struct sun4i_tcon_quirks sun8i_a33_quirks = {