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SubjectRe: [PATCH v3 2/9] drm/sun4i: tcon: Add TCON LCD support for R40
Hi,

On Thu, Jan 02, 2020 at 10:04:40PM +0530, Jagan Teki wrote:
> On Thu, Jan 2, 2020 at 9:17 PM Maxime Ripard <mripard@kernel.org> wrote:
> >
> > On Thu, Jan 02, 2020 at 09:10:31PM +0530, Jagan Teki wrote:
> > > On Thu, Jan 2, 2020 at 4:24 PM Maxime Ripard <mripard@kernel.org> wrote:
> > > >
> > > > On Tue, Dec 31, 2019 at 06:35:21PM +0530, Jagan Teki wrote:
> > > > > TCON LCD0, LCD1 in allwinner R40, are used for managing
> > > > > LCD interfaces like RGB, LVDS and DSI.
> > > > >
> > > > > Like TCON TV0, TV1 these LCD0, LCD1 are also managed via
> > > > > tcon top.
> > > > >
> > > > > Add support for it, in tcon driver.
> > > > >
> > > > > Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
> > > > > ---
> > > > > Changes for v3:
> > > > > - none
> > > > >
> > > > > drivers/gpu/drm/sun4i/sun4i_tcon.c | 8 ++++++++
> > > > > 1 file changed, 8 insertions(+)
> > > > >
> > > > > diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c b/drivers/gpu/drm/sun4i/sun4i_tcon.c
> > > > > index fad72799b8df..69611d38c844 100644
> > > > > --- a/drivers/gpu/drm/sun4i/sun4i_tcon.c
> > > > > +++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c
> > > > > @@ -1470,6 +1470,13 @@ static const struct sun4i_tcon_quirks sun8i_a83t_tv_quirks = {
> > > > > .has_channel_1 = true,
> > > > > };
> > > > >
> > > > > +static const struct sun4i_tcon_quirks sun8i_r40_lcd_quirks = {
> > > > > + .supports_lvds = true,
> > > > > + .has_channel_0 = true,
> > > > > + /* TODO Need to support TCON output muxing via GPIO pins */
> > > > > + .set_mux = sun8i_r40_tcon_tv_set_mux,
> > > >
> > > > What is this muking about? And why is it a TODO?
> > >
> > > Muxing similar like how TCON TOP handle TV0, TV1 I have reused the
> > > same so-that it would configure de port selection via
> > > sun8i_tcon_top_de_config
> > >
> > > TCON output muxing have gpio with GPIOD and GPIOH bits, which select
> > > which of LCD or TV TCON outputs to the LCD function pins. I have
> > > marked these has TODO for further support as mentioned by Chen-Yu in
> > > v1[1].
> >
> > It should be in the commit log.
>
> Make sense.
>
> > What's the plan to support that when needed? And that means that the
> > LCD and TV outputs are mutually exclusive? We should at the very least
> > check that both aren't enabled at the same time.
>
> Yes, LCD or TV within the outselect seems to be mutually exclusive.
> Like LCD0 or TV0 can output to GPIOD incase of TV0_OUTSEL and LCD1 or
> TV1 can output to GPIOH incase of TV1_OUTSEL. I think checking them
> before configuring TCON_TOP_PORT_SEL_REG would make sense, let me know
> if you have any suggestions?

Making sure in atomic_check that TV and LCD are not used at the same
time, and then in encoders mode_set / enable mux the pins to our
encoders would be my first guess.

Maxime
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