Re: Virtio-GPU Xres and Yres seettings

[Pratik Parvati]

I apologise for not putting the question properly. I am referring virtio spec to understand the driver and device operation - I had a few questions on pixel data, as it was not working as expected.

My display is working fine now; thanks for your help.

Regards,

Pratik

On Tue, 21 Dec 2021 at 16:41, Gerd Hoffmann <kraxel@redhat.com> wrote:

On Mon, Dec 20, 2021 at 10:44:06PM +0530, Pratik Parvati wrote:
> > EDID is optional, so you can try disable the EDID feature bit and see
> > what happens.
>
> Thanks Gerd, after disabling the EDID, I was able to get the required
> resolution (basically width and height) from the driver.
>
> Another strange observation - When the device receives the
> command VIRTIO_GPU_CMD_RESOURCE_ATTACH_BACKING with the number of
> entries having a pixel data in scatter gather format, the device is trying
> to store these bytes in contiguous memory. When I read those sg memory, the
> device receives all zeros from the driver (for a 1024x768 display,
> the device receives 3MB of data from the driver). Is this an expected
> behaviour? - If not, what is the driver trying to display on the screen?

How about reading the virtio spec?
display updates are handled with transfer and flush commands.

take care,
  Gerd