[nexus7-flo] backlight brightness

[Rob Clark]

On Fri, Apr 29, 2016 at 1:32 AM, Vinay Simha <simhavcs at gmail.com> wrote:
> hi,
>
> In nx7, backlight brightness control is controlled by dcs commands of
> MIPI_DCS_SET_DISPLAY_BRIGHTNESS.
> there is no PWM going to panel interface directly as we have in ifc6410/nx5

afaiu it is not uncommon to need to control backlight via panel (ie, I
think basically all adaptive-backlight panels).  I think the answer is
for these panels, the panel driver would register it's own backlight
driver, rather than get a (pwm, etc) backlight via dt bindings.

Possibly if the backlight commands are standardized enough then we
could implement a single drm_panel_dsi_backlight helper which could be
created by any of the dsi adaptive-backlight panels (ie. pass in a
'struct mipi_dsi_device *').. something like:

struct drm_panel_dsi_backlight {
    struct mipi_panel_dsi_device *link;
    ...
}

struct backlight_device *drm_panel_create_dsi_backlight(struct
mipi_panel_dsi_device *link)
{
    struct drm_panel_dsi_backlight *dsi_bl;
    ...
    return devm_backlight_device_register(&link->dev, ..., dsi_bl,
dsi_bl_ops, props);
}

BR,
-R