Re: [PATCH v2 00/10] drm: Add driver for PowerPC OF displays

Hello,

On Thu, Jul 28, 2022 at 09:13:59PM +1000, Michael Ellerman wrote:

Thomas Zimmermann [off-list ref] writes:

quoted

(was: drm: Add driverof PowerPC OF displays)

PowerPC's Open Firmware offers a simple display buffer for graphics
output. Add ofdrm, a DRM driver for the device. As with the existing
simpledrm driver, the graphics hardware is pre-initialized by the
firmware. The driver only provides blitting, no actual DRM modesetting
is possible.

Hi Thomas,

I tried to test this on a 32-bit ppc Mac Mini but didn't have much luck.
But I'm probably doing something wrong because I'm a graphics noob.

The machine normally uses CONFIG_DRM_RADEON, so I turned that off, and
turned DRM_OFDRM on.

When I boot I get boot messages but only one screen worth, the messages
don't scroll at all, which is unusual. But I'm not sure if that's
related to ofdrm or something else.

A somewhat interesting datapoint might be how this works with offb.

The machine does come up, I can login via SSH. Is there some way to
start X to exercise the driver from an SSH login?

The startx script provided by distribution usually works.

It's basically a very convoluted way to do something like

X :0&
DISPLAY=:0 xterm&

Thanks

Michal