drm/i915: Treat SAGV block time 0 as SAGV disabled
For modern platforms the spec explicitly states that a SAGV block time of zero means that SAGV is not supported. Let's extend that to all platforms. Supposedly there should be no systems where this isn't true, and it'll allow us to: - use the same code regardless of older vs. newer platform - wm latencies already treat 0 as disabled, so this fits well with other related code - make it a bit more clear when SAGV is used vs. not - avoid overflows from adding U32_MAX with a u16 wm0 latency value which could cause us to miscalculate the SAGV watermarks on tgl+ Cc: stable@vger.kernel.org Signed-off-by:Ville Syrjälä <ville.syrjala@linux.intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20220309164948.10671-2-ville.syrjala@linux.intel.com Reviewed-by:
Stanislav Lisovskiy <stanislav.lisovskiy@intel.com> (cherry picked from commit d8f5855b ) Signed-off-by:
Tvrtko Ursulin <tvrtko.ursulin@intel.com>
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9cddf03b
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