[Letux-kernel] DSI & DPI panels with omapdrm on 4.20-rc

Tomi Valkeinen tomi.valkeinen at ti.com
Fri Nov 16 13:46:24 CET 2018

On 15/11/18 17:50, H. Nikolaus Schaller wrote:
> Hi Tomi,
>> Am 15.11.2018 um 12:17 schrieb Tomi Valkeinen <tomi.valkeinen at ti.com
>> <mailto:tomi.valkeinen at ti.com>>:
>> On 15/11/18 08:00, H. Nikolaus Schaller wrote:
>>> But also DISPC_POL_FREQ.
>> Can you try the attached hack patch?
> Seems to fix something. I now have a desktop back on the panel :)

Ok. I need to discuss with Laurent about this when he gets back.

> What I have observed is that the panel dimensions in mm seem to have
> changed (because our GUI software uses that as a scaling factor).

Which panel driver is this? Does "changed" mean that they were correct
previously, and not anymore? What are/were the numbers?

> When reworking the dsi panel drivers, I have seen that panel drivers
> can now report the dimensions in mm. So does the generic DPI driver have
> a new default here? Can it be specified by new DT properties?
> But I have to check that I do not have a user-space bug here.

panel-dpi.c has not and does not supported physical size. There's code
in omap_connector.c that calls get_size() to get the size. You could add
debug prints there to see if it's called and what are the numbers.

> How does omapdrm X11 handle the mouse cursor? By an overlay of the
> OMAP3 DSS? Then there may be some other bits for the overlay priority
> depend on driver probe sequence (the td028ttec1 is probed as an SPI
> client, probably before omapdrm but I don't know).

If I recall right, omap xdriver has a config option for HW or SW cursor,
and HW cursor uses a plane with legacy modesetting to show the cursor.
HW cursor has always been buggy, but apparently something has changed,
causing the plane not to be transparent.


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