[Mesa-dev] [PATCH v5] i965: Fix ETC2/EAC GetCompressed* functions on Gen7 GPUs

[Eleni Maria Stea]

On 06/14/2018 10:27 PM, Nanley Chery wrote:

> +Jason, Ken
> 
> Hello,
> 
> I recently did some miptree work relating to the r8stencil_mt and I
> think I now have a more informed opinion about how things should be
> structured. I'd like to propose an alternative solution.
> 
> I had initially thought we should have a separate miptree to hold the
> compressed data, like this patch does, but now I think we should
> actually have the compressed data be the main miptree and to store the
> decompressed miptree as part of the main one. The reasoning is that we
> could reuse this structure to handle the r8stencil workaround and to
> eventually handle the ASTC_LDR surfaces that are modified on gen9.
> 
> I'm proposing something like the following:
> 
> 1. Rename r8stencil_mt ->shadow_mt and
>    r8stencil_needs_update -> shadow_needs_update.
> 2. Make shadow_mt hold the decompressed ETC miptree
> 3. Update shadow_needs_update whenever the main mt is modified
> 4. Add an function to update the shadow_mt using the main mt as a source
> 5. Sample from the shadow_mt as appropriate
> 6. Make the main miptree hold the compressed data
> 
> This method should also be able to handle the CopyImage functions. What
> do you all think?
> 
> -Nanley

Hi Nanley,

Thank you for your reply. I wasn't aware that there are other cases we
might need to store a 2nd image. I agree that it's more reasonable to
use one generic purpose miptree that can be accessible from different
parts of the i965 code for such cases instead of storing miptrees in
different places for different hacks when a feature is not supported.

I will search your patch to get a look and I will also get a look at the
mesa code to see how easy this fix would be (which parts of the code it
might affect) and if everyone agrees that this is a good idea I will
modify this patch according to your suggestions.

BR :)
Eleni