[RFC V3 2/3] drm/bridge: add a dummy panel driver to support lvds bridges

Thierry Reding thierry.reding at gmail.com
Sat May 17 14:14:04 PDT 2014

On Thu, May 15, 2014 at 05:10:16PM +0530, Ajay kumar wrote:
> On Thu, May 15, 2014 at 1:43 PM, Thierry Reding <thierry.reding at gmail.com> wrote:
> > I still don't see how controlling the enable GPIO from the panel will be
> > in any way better, or different for that matter, from simply enabling
> > the backlight and let the backlight driver handle the enable GPIO. Have
> > you tried to do that and found that it doesn't work?
> It works, but it gives me glitch when I try to configure video.
> This is because backlight_on(pwm-backlight) happens much before
> I configure video(inside drm), and while configuring video there would
> be a glitch,
> and that glitch would be visible to the user since backlight is already enabled.

Okay, so this means that your backlight is turned on too early. Instead
of working around that problem by moving control of the backlight enable
GPIO from the backlight driver into the panel driver, the correct way to
fix it is to make sure the backlight stays off until video is ready.

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