Re: [PATCH 2/2] drm/i915: l3 parity sysfs interface

[Ben Widawsky <ben@bwidawsk.net>]

On Fri, 13 Apr 2012 18:39:24 -0700
Ben Widawsky <ben@bwidawsk.net> wrote:

> On Sat, 14 Apr 2012 00:24:03 +0100
> Chris Wilson <chris@chris-wilson.co.uk> wrote:
> 
> > On Fri, 13 Apr 2012 16:05:14 -0700, Ben Widawsky <ben@bwidawsk.net>
> > wrote:
> > > Dumb binary interfaces which allow root-only updates of our cache
> > > remapping registers.  See intel-gpu-tools for how this can/should
> > > be used.
> > 
> > Initial comments: don't bother posting a read just before a read,
> > and do return errors from the sysfs read/write functions (the return
> > value is signed for that purpose). A lesser issue is that if you are
> > worried about necessity of posting-reads, you should also worry
> > about the effect of the weak ordering of writes.
> > -Chris
> > 
> 
> Thanks for the advice on the sysfs return values. Some of the code I
> was referring from just returns 0, but this seems to be not the right
> thing to do after looking further into it.
> 
> As for the POSTING_READ it was intentional. Unless reads are always in
> order??? I have to make sure the clock gating disable propogates
> before I can read the L3 registers.
>

On further thought, yeah - you are right.