On 03/21/2017 11:20 AM, Ceraolo Spurio, Daniele wrote:
On 3/21/2017 2:02 AM, Oscar Mateo wrote:
Doorbell release flow requires that we wait for GEN8_DRB_VALID bit to go
to zero after updating db_status before we call the GuC to release the
doorbell.
Kudos to Daniele for finding this out.
v2: WARN instead of DRM_ERROR (Joonas)
Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@xxxxxxxxx>
Signed-off-by: Oscar Mateo <oscar.mateo@xxxxxxxxx>
Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@xxxxxxxxx>
I'd like Joonas to give his ack on not returning after the wait since
he commented on it in the previous version. I personally prefer it
this way because we gain a bit more time for the doorbell to disable
itself (there is no spec in regards to how long this should take, but
it should be quick) while the GuC processes the H2G. If we ever see a
case where the warn fires but the H2G is successful it would mean that
we have to tune our wait time.
Thanks,
Daniele
True. I went with his second option (WARN instead of DRM_ERROR) without
asking him first...
Thanks,
-- Oscar
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