On Wed, Mar 08, 2017 at 11:51:39AM +0800, Chen-Yu Tsai wrote:

On Tue, Mar 7, 2017 at 4:56 PM, Maxime Ripard
[off-list ref] wrote:

quoted

Even though that mux is undocumented, it seems like it needs to be set to 1
when using composite, and 0 when using HDMI.

Signed-off-by: Maxime Ripard <redacted>
---
 drivers/gpu/drm/sun4i/sun4i_tcon.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c b/drivers/gpu/drm/sun4i/sun4i_tcon.c
index d2335f109601..93249c5ab1e4 100644
--- a/drivers/gpu/drm/sun4i/sun4i_tcon.c
+++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c

@@ -268,11 +268,16 @@ void sun4i_tcon1_mode_set(struct sun4i_tcon *tcon, struct drm_encoder *encoder,
                           SUN4I_TCON_GCTL_IOMAP_MASK,
                           SUN4I_TCON_GCTL_IOMAP_TCON1);

+       if (encoder->encoder_type == DRM_MODE_ENCODER_TVDAC)
+               val = 1;
+       else
+               val = 0;
+
        /*
         * FIXME: Undocumented bits
         */
        if (tcon->quirks->has_unknown_mux)
-               regmap_write(tcon->regs, SUN4I_TCON_MUX_CTRL_REG, 1);
+               regmap_write(tcon->regs, SUN4I_TCON_MUX_CTRL_REG, val);

We might want to do this the other way around, i.e. exporting

    int sun4i_tcon_mux_set(struct drm_device *drm, int encoder_type,
                           int pipeline)

and have downstream encoders call it. For the A31, the mux is not exclusively
used for channel 1; there is a mux setting for MIPI DSI as well, but AFAIK
DSI is connected to channel 0.

We could make it part of sun4i_tcon_channel_enable too, though. What
do you think?

Additionally, the mux registers are only valid in the first TCON, meaning
it must available be active in 2 pipeline chips. It's also why we'd pass
"struct drm_device *" instead of "struct sun4i_tcon *".

Hmmmm. That's going to be tricky to support. Has this been confirmed
somehow? Is the register used for something else on TCON1?

Thanks,
Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
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