Hi Rodrigo,
Thank you very much for providing that information in a precise manner.
Às 07:16 de 05/05/21, Rodrigo Vivi escreveu:
Hi Andre,
I'm not familiar with the sample c message optimization.
Probably Ken can comment.
However I could check the internal spec here and I saw this bit
only exists with this meaning in Haswell.
For all the other platforms, including Broadwell it got re-purposed with
a different meaning and a programming note:
"This bit should be programmed to zero (0h) at all times."
Also, I could not find any workaround documented anywhere recommending
this bit to be set.
So, I would not recommend to use it in any product, even downstream.
Regardless the state of sample c message optimization in later platforms.
Thanks,
Rodrigo.
On Tue, May 04, 2021 at 08:07:14PM -0300, André Almeida wrote:
Hi there,
While browsing an old downstream kernel, I found a patch[0] that enables
sample_c optimizations at Broadwell GPUs. The message from the upstream
commit that enables it for Haswell[1] (and presumably where the code at[0]
was copied from) states that "[..] later platforms remove this bit, and
apparently always enable the optimization".
Could you confirm that Broadwell and following architectures enable this
optimization by default (and thus, patch[0] is a no-op), or should I
upstream it?
Thanks,
André
[0] https://github.com/ValveSoftware/steamos_kernel/commit/198990f13e1d9429864c177d9441a6559771c5e2
[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=944115934436b1ff6cf773a9e9123858ea9ef3da
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