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SubjectRe: [PATCH 1/4] drm/sun4i: tcon: Support an active-low DE signal with RGB interface
On Tue, Oct 23, 2018 at 11:33:10AM +0200, Paul Kocialkowski wrote:
> Hi,
>
> Le mercredi 10 octobre 2018 à 16:57 +0200, Maxime Ripard a écrit :
> > On Wed, Oct 10, 2018 at 01:41:31PM +0200, Paul Kocialkowski wrote:
> > > Some panels need an active-low data enable (DE) signal for the RGB
> > > interface. This requires flipping a bit in the TCON0 polarity register
> > > when setting up the mode for the RGB interface.
> > >
> > > Add a new helper function to match specific bus flags and use it to set
> > > the polarity inversion bit for the DE signal when required.
> > >
> > > Signed-off-by: Paul Kocialkowski <contact@paulk.fr>
> > > ---
> > > drivers/gpu/drm/sun4i/sun4i_tcon.c | 28 ++++++++++++++++++++++++++--
> > > drivers/gpu/drm/sun4i/sun4i_tcon.h | 1 +
> > > 2 files changed, 27 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c b/drivers/gpu/drm/sun4i/sun4i_tcon.c
> > > index 3fb084f802e2..d249a462ec09 100644
> > > --- a/drivers/gpu/drm/sun4i/sun4i_tcon.c
> > > +++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c
> > > @@ -78,6 +78,24 @@ static int sun4i_tcon_get_pixel_depth(const struct drm_encoder *encoder)
> > > return -EINVAL;
> > > }
> > >
> > > +static bool sun4i_tcon_match_bus_flags(const struct drm_encoder *encoder,
> > > + u32 bus_flags)
> > > +{
> > > + struct drm_connector *connector;
> > > + struct drm_display_info *info;
> > > +
> > > + connector = sun4i_tcon_get_connector(encoder);
> > > + if (!connector)
> > > + return false;
> > > +
> > > + info = &connector->display_info;
> > > +
> > > + if ((info->bus_flags & bus_flags) == bus_flags)
> > > + return true;
> > > +
> > > + return false;
> > > +}
> > > +
> > > static void sun4i_tcon_channel_set_status(struct sun4i_tcon *tcon, int channel,
> > > bool enabled)
> > > {
> > > @@ -415,6 +433,7 @@ static void sun4i_tcon0_mode_set_lvds(struct sun4i_tcon *tcon,
> > > }
> > >
> > > static void sun4i_tcon0_mode_set_rgb(struct sun4i_tcon *tcon,
> > > + const struct drm_encoder *encoder,
> > > const struct drm_display_mode *mode)
> > > {
> > > unsigned int bp, hsync, vsync;
> > > @@ -474,8 +493,13 @@ static void sun4i_tcon0_mode_set_rgb(struct sun4i_tcon *tcon,
> > > if (mode->flags & DRM_MODE_FLAG_PVSYNC)
> > > val |= SUN4I_TCON0_IO_POL_VSYNC_POSITIVE;
> > >
> > > + if (sun4i_tcon_match_bus_flags(encoder, DRM_BUS_FLAG_DE_LOW))
> > > + val |= SUN4I_TCON0_IO_POL_DE_NEGATIVE;
> > > +
> >
> > There's other flags in use in that function, you should also migrate
> > them (ideally by splitting that new function into a separate patch).
>
> Actually, these other flags are not DRM bus flags but DRM mode flags,
> which can be accessed directly from the mode pointer passed as
> argument. Thus, they don't require a helper.

I was talking about DRM_BUS_FLAG_PIXDATA_POSEDGE and
DRM_BUS_FLAG_PIXDATA_NEGEDGE, which are in the current tree.

Maxime

--
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

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