intel: Initialize FF_MODE2 on all Gfx12 platforms
On Alchemist, the FF_MODE2 documentation says that we must set the
FF_MODE2 timer values for GS and HS to 224. The hardware performance
tuning guide also recommends setting the TDS timer to 4.
On Tigerlake, i915 applies workarounds to set the GS timer to 224
(failing to do so can cause HS/DS unit hangs), and the TDS timer to 4
(for performance). It doesn't currently apply a HS timer there, and
I'm not sure if it's strictly necessary, but given that Alchemist
needed it, and the other two settings matched, let's assume that it
ought to match as well.
Unfortunately, there has been a bug in the i915 workarounds
infrastructure for non-masked context registers where writing one
field of the register zeroes out all the others. So, I believe the
Tigerlake TDS timer value of 4 isn't being applied correctly there,
though the register is also not readable on that platform which
makes it hard to verify. So, this may also speed up tessellation.
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/9233
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
Cc: mesa-stable
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/23839>
4 files changed
