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On PTL platforms with media version 30.00, the fuse registers for reporting L3 bank availability to the GT just read out as ~0 and do not provide proper values. Xe does not use the L3 bank mask for anything internally; it only passes the mask through to userspace via the GT topology query. Since we don't have any way to get the real L3 bank mask, we don't want to pass garbage to userspace. Passing a zeroed mask or a copy of the primary GT's L3 bank mask would also be inaccurate and likely to cause confusion for userspace. The best approach is to simply not include L3 in the list of masks returned by the topology query in cases where we aren't able to provide a meaningful value. This won't change the behavior for any existing platforms (where we can always obtain L3 masks successfully for all GTs), it will only prevent us from mis-reporting bad information on upcoming platform(s). There's a good chance this will become a formal workaround in the future, but for now we don't have a lineage number so "no_media_l3" is used in place of a lineage as the OOB workaround descriptor. v2: - Re-calculate query size to properly match data returned. (Gustavo) - Update kerneldoc to clarify that the L3bank mask may not be included in the query results if the hardware doesn't make it available. (Gustavo) Cc: Matt Atwood <matthew.s.atwood@intel.com> Cc: Gustavo Sousa <gustavo.sousa@intel.com> Signed-off-by:
Shekhar Chauhan <shekhar.chauhan@intel.com> Co-developed-by:
Matt Roper <matthew.d.roper@intel.com> Signed-off-by:
Jonathan Cavitt <jonathan.cavitt@intel.com> Reviewed-by:
Gustavo Sousa <gustavo.sousa@intel.com> Acked-by:
Francois Dugast <francois.dugast@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20241007154143.2021124-2-matthew.d.roper@intel.com
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