Re: [RFC PATCH] drm/panel: Make backlight attachment lazy

[Thierry Reding]

On Mon, Dec 07, 2020 at 10:44:46PM -0600, Bjorn Andersson wrote:
> Some bridge chips, such as the TI SN65DSI86 DSI/eDP bridge, provides
> means of generating a PWM signal for backlight control of the attached
> panel. The provided PWM chip is typically controlled by the
> pwm-backlight driver, which if tied to the panel will provide DPMS.
> 
> But with the current implementation the panel will refuse to probe
> because the bridge driver has yet to probe and register the PWM chip,
> and the bridge driver will refuse to probe because it's unable to find
> the panel.

What you're describing is basically a circular dependency. Can't we get
rid of that in some other way? Why exactly does the bridge driver refuse
to probe if the panel can't be found?

In other words, I see how the bridge would /use/ the panel in that it
forward a video stream to it. But how does the panel /use/ the bridge?

Thierry

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