V3D UIF texture format conversion with TFU

[Alejandro Piñeiro]

Hi,

sorry, I realized that you sent first this email to me privately, but 
didn't have time to reply.

On 1/3/24 14:33, Macoy Madson wrote:
> Hello,
>
> I have been looking at the code in Gallium/drivers/v3d related to 
> texture conversion, specifically v3dx_tfu.c.
>
> I have been trying to find how to convert a texture from raster format 
> RGBA8 to UIF (either XOR or NO_XOR). I tried break-pointing the 
> v3dX(tfu) function, but it doesn't appear to be called in my simple 
> textured triangle OpenGL program on a Raspberry Pi 4 (VideoCore VI v. 
> 42).
>
> I am looking for where this conversion takes place, as it appears the 
> VideoCore expects textures to be in another format before they can be 
> sampled properly.
>
> Is there anyone here who can point me to any one of the following:
>
> - How v3dX(tfu) ends up getting used (e.g., a user-space program I can 
> run to blit/convert a raster texture into a UIF texture)
>
> - Any notes on the TFU interface itself (what the registers expect, 
> beyond what can clearly infer from v3dX(tfu))
>
> - If the TFU isn't used to convert to UIF, where the conversion takes 
> place
>
> I may have misunderstood the texture sampler. I am sampling a texture 
> successfully (pixels are the color I expect) but the pixels are 
> completely "out of order", which is what hints me that they need to be 
> in UIF instead of raster format.
>
> I would greatly appreciate someone to bounce a few V3D questions off of.
>
> Thanks,
>
> Macoy Madson
>
> (Apologies if this was received before; I checked the archive and 
> didn't see it, so I subscribed to the list and re-sent in case I need 
> to be a subscriber to send. I sent this to mesa-dev since I am looking 
> for low level details, so if this should go to the mesa list instead 
> please let me know.)


For this kind of things it is usually done through gitlab issues. Would 
it be possible if you create an issue with that, and additionally adding 
the simple texture triangle program that you mentioned before?


Thanks


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>