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

H. Nikolaus Schaller hns at goldelico.com
Thu Nov 15 16:50:50 CET 2018

Hi Tomi,

> Am 15.11.2018 um 12:17 schrieb Tomi Valkeinen <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 :)

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).

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.

There is only minor glitch (which did exist before but I did never
care much about) that the X11 cursor background is not transparent.
There is a ca. 64x64 black pixel square where the pointer is drawn inside.

I tried to make a screenshot - but it excludes the mouse pointer. So
I did take a photo.

Interestingly, I have seen this only on this DPI panel which uses the
panel-dpi driver. Not on the td028ttec1 or DSI panels (well the dsi
panels don't show anything, but let's fix one thing after the other).

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).

> I think the bus_flags are never handled with panel-dpi.
> I also think there's something odd with the bus_flag handling in
> omap_encoder_mode_set(), but that probably is not causing issues here.

BR and thanks for the quick fix,

> Tomi
> -- 
> Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
> Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
> <0001-hackfix-bus-flags.patch>

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