[PATCH 1/4] drm/tilcdc: add TI LCD Controller DRM driver (v3)

[linux@arm.linux.org.uk (Russell King - ARM Linux)]

On Wed, Jan 23, 2013 at 07:24:33AM -0600, Rob Clark wrote:
> On Wed, Jan 23, 2013 at 3:42 AM, Jean-Francois Moine <moinejf@free.fr> wrote:
> > Hi Rob,
> >
> > As I wanted to re-use your nxp-tda998x driver for the Marvell Dove SoC,
> > I had a look at your IT LCD driver. Comments below.
> 
> Just fyi, you can re-use the nxp-tda998x part independently of tilcdc
> (just in case that wasn't clear).

Great, this chip is also used on the cubox too.

The one thing I wonder is how you deal with the VSYNC/HSYNC polarities
that are provided to the TDA9988x chip.  On the cubox, I have to adjust
the mode parameters such that the polarities are fixed up thusly:

        adjusted->flags &= ~(DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_NHSYNC |
                             DRM_MODE_FLAG_PVSYNC | DRM_MODE_FLAG_NVSYNC |
                             DRM_MODE_FLAG_PCSYNC | DRM_MODE_FLAG_NCSYNC);

        /* The TDA19988 always requires negative VSYNC? */
        adjusted->flags |= DRM_MODE_FLAG_NVSYNC;

        /* The TDA19988 requires positive HSYNC on 1080p or 720p */
        if ((adjusted->hdisplay == 1920 && adjusted->vdisplay == 1080) ||
            (adjusted->hdisplay == 1280 && adjusted->vdisplay == 720))
                adjusted->flags |= DRM_MODE_FLAG_PHSYNC;
        else
                adjusted->flags |= DRM_MODE_FLAG_NHSYNC;

        return true;

for these resolutions to be displayed correctly.

Also, when the only output is the HDMI device, reporting the display
"disconnected" and without any modes seems to cause problems - I have to
report "unknown" status when there's nothing connected, and also provide
a default (720p) mode when no EDID is received.