Re: [RFC PATCH] Revert "drm/i915: Disable compression tricks on JSL"

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Wed, Mar 05, 2025 at 05:00:26PM +0000, Sebastian Brzezinka wrote:
> Hi Ville
> 
> On Wed Mar 5, 2025 at 3:26 PM UTC, Ville Syrjälä wrote:
> > On Wed, Mar 05, 2025 at 02:49:46PM +0000, Sebastian Brzezinka wrote:
> >> This reverts commit 0ddae025ab6cefa9aba757da3cd1d27908d70b0e.
> >> 
> >> According to bspec 14181, CACHE_MODE_0 is a register that's under userspace
> >> control, and DISABLE_REPACKING_FOR_COMPRESSION workaround should be already
> >> in all recent Mesa releases. So, there is no need to include it in kernel.
> >
> > igt doesn't have it.
> >
> >> 
> >> Also, this workaround·sporadically fails to load:
> >> ```
> >> ERROR GT0: engine workaround lost on application! (reg[7000]=0x0,
> >> relevant bits were 0x0 vs expected 0x8000)
> >> ```
> >
> > If it somehow fails to load from the kernel why would it
> > work from userspace?
> >
> > Hmm, apparently CACHE_MODE_0 needs the mcr steering stuff.
> > Does that fix the verification fail?
> 
> Thanks for sugestion. Right now I think that I try to move this wa to
> icl_ctx_workarounds_init as both Mat and Chriss notice that register
> is a part of the context. 

Hmm, didn't realize there was a separate list for that. It looks to
me like there are a bunch of context saved registers handled in
the enging_ctx() stuff currently. I think someone needs to go through
all this stuff and relocate all the registers to their correct spots.

-- 
Ville Syrjälä
Intel