Hi Chen-Yu,

On Sat, Sep 30, 2017 at 3:58 PM, Chen-Yu Tsai [off-list ref] wrote:

On Sat, Sep 30, 2017 at 1:35 PM, Julian Calaby [off-list ref] wrote:

quoted

Hi Chen-Yu,

On Fri, Sep 29, 2017 at 8:22 PM, Chen-Yu Tsai [off-list ref] wrote:

quoted

On Fri, Sep 29, 2017 at 6:20 PM, Maxime Ripard
[off-list ref] wrote:

quoted

On Fri, Sep 29, 2017 at 08:22:56AM +0000, Chen-Yu Tsai wrote:

quoted

On systems with 2 TCONs such as the A31, it is possible to demux the
output of the TCONs to one encoder.

Add support for this for the A31.

Signed-off-by: Chen-Yu Tsai <redacted>
---
 drivers/gpu/drm/sun4i/sun4i_tcon.c | 38 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c b/drivers/gpu/drm/sun4i/sun4i_tcon.c
index 7bf51abaee97..c949309d4285 100644
--- a/drivers/gpu/drm/sun4i/sun4i_tcon.c
+++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c

@@ -112,6 +112,21 @@ void sun4i_tcon_enable_vblank(struct sun4i_tcon *tcon, bool enable)
 }
 EXPORT_SYMBOL(sun4i_tcon_enable_vblank);

+static struct sun4i_tcon *sun4i_get_first_tcon(struct drm_device *drm)

Would that make sense to make it a bit more generic, and pass the id
to look for as an argument?

The reason to look for TCON0 explicitly is to access the muxing registers, which
are only available in TCON0. Other than that, there's nothing else
shared between
the two TCONs. So there's no particular reason to look for TCON1 explicitly.

In that case: in the bizarre case where we're trying to use this mux
type and there is no TCON0, shouldn't we fail?

It gives out a big warning, indicating something is wrong. If TCON0 is not found
it is most likely your device tree is broken. There's nothing more the
driver can do.
Are you suggesting to return NULL in this case, and also do error
handling in the
callers?

You're already returning -EINVAL for other failure cases, so a lack of
TCON0 might as well do the same.

quoted

(Also, the code doesn't make sense if we have some TCON1 and TCON2 in
that order as it'll return TCON2)

I'm guessing you want it to return NULL.

I'm just pointing out the mismatch between getting the "first" TCON
and the actual behaviour.

Thanks,

-- 
Julian Calaby

Email: julian.calaby at gmail.com
Profile: http://www.google.com/profiles/julian.calaby/