On Thu, Aug 08, 2013 at 02:37:35PM +0100, Chris Wilson wrote:
The extended state bits are stored in the LCA register and affect all
updates to the LCA register - i.e. the state on the old context is saved
when SAVE_EX_STATE_EN is currently set in the old context address before
the update, and the new context is restored when RESTORE_EX_STATE_EN is
set in the new context address. This is irrespective of the
RESTORE_INHIBIT flag in the MI_SET_CONTEXT.
Hence, upon initial loading the contents of the extended state is read
from uninitialised data. To workaround this, on first load we do a dummy
load without the mandatory RESTORE_EX_STATE_EN bit so that the real load
causes us to initialise the extended state of the context before it is
then loaded by the LCA update.
References: https://bugs.freedesktop.org/show_bug.cgi?id=64073
Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
Cc: Ben Widawsky <b...@bwidawsk.net>
If you split this up in 2, the variable length for mi_set_context, and
the workaround - the variable length thing is:
Reviewed-by: Ben Widawsky <b...@bwidawsk.net>
I'd like to dig a bit more at the workaround portion.
--
Ben Widawsky, Intel Open Source Technology Center
_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
http://lists.freedesktop.org/mailman/listinfo/intel-gfx
