[Intel-gfx] [PATCH 2/3] drm/i915/bxt: add revision id for A1 stepping and use it

[Ville Syrjälä]

On Tue, Oct 13, 2015 at 04:16:47PM +0300, Jani Nikula wrote:
> On Wed, 07 Oct 2015, Jani Nikula <jani.nikula at intel.com> wrote:
> > On Tue, 06 Oct 2015, Ville Syrjälä <ville.syrjala at linux.intel.com> wrote:
> >> On Tue, Oct 06, 2015 at 04:43:11PM +0300, Jani Nikula wrote:
> >>> On Tue, 06 Oct 2015, Ville Syrjälä <ville.syrjala at linux.intel.com> wrote:
> >>> > On Tue, Oct 06, 2015 at 02:41:15PM +0300, Jani Nikula wrote:
> >>> >> Prefer inclusive ranges for revision checks rather than "below B0". Per
> >>> >> specs A2 is not used, so revid <= A1 matches revid < B0.
> >>> >
> >>> > The w/a db would say UNTIL_B0 etc., so might be easier to check against
> >>> > it if we keep to the same convention.
> >>> 
> >>> So I wanted to double check what the convention is. I picked
> >>> WaRsDisableCoarsePowerGating.
> >>> 
> >>> KBL - SIWA_FOREVER
> >>> BXT - SI_WA_BEFORE(BXT_REV_ID_B0)
> >>> SKL - SIWA_UNTIL_SKL_E0
> >>> 
> >>> Description "Disable coarse power gating for GT4 until GT F0 stepping."
> >>> 
> >>> *rolls eyes*
> >>> 
> >>> So is that "until" there inclusive or non-inclusive? The db is
> >>> contradicting itself...
> >>
> >> Hmm. My recollection was that it's exclusive, but now that I look at
> >> your findings and some other workarounds, it does look a bit more like
> >> inclusive.
> >>
> >> I would think the exclusive thing would be easier to maintain since
> >> the hsd specifies the stepping in which stuff got fixed, and the
> >> exclusive convention would then have the same stepping listed. Eg. if
> >> the hsd says fixed in E0, but the w/a db says UNTIL_D0, then one is
> >> left wondering about D1+ But perhaps such steppings didn't even exist.
> >>
> >> Well, in reality it's all over the place. Eg. looking at the BDW UNTIL_D0
> >> stuff, some are fixed in E0, some are fixed in D0, and at least one was
> >> fixed in B0 according to hsd. So I'm starting to think that the meaning
> >> of the tag depends entirely on the person who pushed the change.
> >
> > With that, I stand by the patches I submitted as they are.
> 
> Ville, opinions, r-b, nak, ack, crap, what? ;)

Yeah, I guess it's all good.

Acked-by: Ville Syrjälä <ville.syrjala at linux.intel.com>

-- 
Ville Syrjälä
Intel OTC