drm/fbdev-dma: regression

[Nuno Gonçalves]

Hi Thomas,

Since 5ab91447aa13b8b98bc11f5326f33500b0ee2c48 and still happening in
master, I often get a kernel crash, either a "Unable to handle kernel
NULL pointer dereference at virtual address" or "Unable to handle
kernel paging request at virtual address".

This happens in ARM64 with ili9225 and display size 220, 176. It also
happens in another board with a different tinydrm driver and size 320,
240.

I've reported in 2022 a bug (that you fixed, thanks!), where it was
related to screen size causing non alignment of scanlines and pages.
I've not investigated further this time as I was not doing any driver
development, but let me know if I can do any further testing.

Thanks,
Nuno