On Fri, Feb 21, 2014 at 11:38:48AM -0800, Ben Widawsky wrote: > On Fri, Feb 21, 2014 at 05:31:59PM +0200, mika.kuopp...@intel.com wrote: > > From: Mika Kuoppala <mika.kuopp...@intel.com> > > > > Sometimes generic driver code gets forcewake explicitly by > > gen6_gt_force_wake_get(), which check forcewake_count before accessing > > hardware. However the register access with gen8_write function access > > low level hw accessors directly, ignoring the forcewake_count. This > > leads to nested forcewake get from hardware, in ring init and possibly > > elsewhere, causing forcewake ack clear errors and/or hangs. > > > > Fix this by checking the forcewake count also in gen8_write > > > > v2: Read side doesn't care about shadowed registers, > > Remove __needs_put funkiness from gen8_write. (Ville) > > Improved commit message. > > > > References: https://bugs.freedesktop.org/show_bug.cgi?id=74007 > > Cc: Ben Widawsky <benjamin.widaw...@intel.com> > > Cc: Ville Syrjälä <ville.syrj...@linux.intel.com> > > Signed-off-by: Mika Kuoppala <mika.kuopp...@intel.com> > > Reviewed-by: Ben Widawsky <b...@bwidawsk.net> > > For those concerned with the performance implication of the extra if > (if anyone at all cares, it's Chris) - I suppose we could also just add > the lock to gen6_gt_force_wake_get/put. > > [snip]
I should have also said, we have very few cases where it's actually a problem (ie. not just done at init). And in fact, I am wondering now how one could hit this at all without enabling rps. -- Ben Widawsky, Intel Open Source Technology Center _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/intel-gfx
