[PATCH v4 00/11] drm: add support for Atmel HLCDC Display Controller

On Thu, Aug 21, 2014 at 10:37:06AM +0200, Boris BREZILLON wrote:

Hi Ludovic,

On Thu, 21 Aug 2014 10:16:19 +0200
Ludovic Desroches [off-list ref] wrote:

quoted

Hi Boris,

You can add

Tested-by: Ludovic Desroches <redacted>

Thanks for testing this driver.

quoted

Only one issue but not related to your patches, you can't display
quickly the bootup logo since the panel detection takes too much
time.

Yes, actually this is related to the device probe order: the
hlcdc-display-controller device is probed before the simple-panel, thus
nothing is detected on the RGB connector (I use of_drm_find_panel to
check for panel availability) when the display controller is
instantiated. I rely on the default polling infrastructure provided by
the DRM/KMS framework which polls for a new connector every 10s, and
this is far more than you kernel boot time.

Do anyone see a solution to reduce this delay (without changing the
polling interval). I thought we could add a notifier infrastructure to
the DRM panel framework, but I'm not sure this is how you want things
done...

Other drivers return -EPROBE_DEFER when a panel hasn't been registered
yet. This will automatically take care of ordering things in a way that
DRM/KMS will only be initialized after the panel has been probed. That
will still cause some delay before everything gets set up, but hopefully
less than what you're seeing now. There's also another thread where this
is being discussed because deferred probing is causing "unacceptable"
delays as well.

Thierry
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