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

[Ben Widawsky <ben@bwidawsk.net>]

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.

Ben