Re: [PATCH 1/6] drm/i915/crt: don't set HOTPLUG bits on !PCH

[Daniel Vetter <daniel.vetter@ffwll.ch>]

On Fri, Oct 12, 2012 at 7:17 PM, Paulo Zanoni <przanoni@gmail.com> wrote:
> Ok, so please do a final test: try to write something to those
> "must-be-preserved" bits and check if the values stay or not. If after
> writing 1 to bits 17-18, 20-23 you read 0, then you have my
> Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>. I still do plan
> to test the 6 patches of the series on hsw later btw.

I've tested a few bits on a few machines, and some do stick and some
cause ... strange things (like a seemingly random set of other
register bits also being set). I guess that's not the answer you've
been looking for. I'd still prefer if we just try to clear things,
worst case we can easily read out the current state of these reserved
bits at boot up and restore them at resume time. But I'd really prefer
if we reduce our reliance on the boot-up state from the bios as much
as possible. And in this case here the only way to figure things out
is to merge it (it's really early for 3.8 anyway) and see what
happens.

Cheers, Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch