TimJTi opened a new pull request, #12733:
URL: https://github.com/apache/nuttx/pull/12733

   The SAMA5D2 LCDC driver has memory mapped framebuffers that LVGL (for 
example) can write to directly causing issues. LVGL - and presumably other 
applications - need a buffer that they can render to and only when done should 
that be copied to the "real" framebuffers of the LCDC.
   
   I have added a function `CONFIG_FB_UPDATE`  that can be called via the 
relevant IOCTL that does the copy and it has fixed the issue I was seeing in 
relation to screen artefacts I noted as an issue in the nuttx-apps repo 
[here](https://github.com/apache/nuttx-apps/issues/2416).
   
   I am not 100% sure what the correct way to address this is, so for now I 
have added a new Kconfig entry to allow an "EXT" memory buffer to be declared, 
and that is what is reported as the `pinfo->fbmem` memory location but it 
doesn't really feel right - and it seems there are no other architectures that 
address this so it is perhaps unique to the SAMA5D2?
   
   There must be a better/neater/proper way to be doing this?
   
   ## Impact
   It allows LVGL V9 to behave as expected, on this processor. I have tried to 
ensure that the driver reverts to the previous methodology if the new Kconfig 
entry is not present.
   
   ## Testing
   Custom board with SAMA5D27-D1G and 800x480 LCDC. Manually deleted new 
Kconfig entry to check the driver reverts to as before and, similarly, deleted 
the newly enforced `CONFIG FB_UPDATE` entry to check.
   
   


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