Re: [PATCH 0/3] HDMI optimization series

[Daniel Vetter <daniel@ffwll.ch>]

On Tue, Aug 11, 2015 at 11:03:54AM +0000, Sharma, Shashank wrote:
> HI Daniel, 
> 
> Looks like we are not getting an IVB machine here. I think instead of blocking the patch set for the whole series, we can just block it for the platforms we don’t get success for.
> We are shipping many VLV/CHV systems with these patches applied, and they are passing all Android test suits and test benches, so we don’t doubt the solution as such.
> 
> We have done testing for following platforms (gen 9 is tested by Imre also):
> 1. CHV / BSW
> 2. SKL
> 3. BXT
> 4. BDW

I know that it works on piles of other platforms too. The problem is
figuring out why it doesn't work on some and what we're doing wrong.

> Why don’t we go ahead with this solution for gen 8 onwards, and keep the
> rest of the code un touched, this will serve both the purpose.

I guess we can, but if we get a regression report on bdw because of this
I'll be furious.
-Daniel

> 
> Regards
> Shashank 
> -----Original Message-----
> From: Intel-gfx [mailto:intel-gfx-bounces@lists.freedesktop.org] On Behalf Of Daniel Vetter
> Sent: Tuesday, August 11, 2015 3:12 PM
> To: Jindal, Sonika
> Cc: intel-gfx@lists.freedesktop.org
> Subject: Re: [Intel-gfx] [PATCH 0/3] HDMI optimization series
> 
> On Mon, Aug 10, 2015 at 02:05:47PM +0530, Jindal, Sonika wrote:
> > 
> > 
> > On 8/10/2015 1:38 PM, Daniel Vetter wrote:
> > >On Mon, Aug 10, 2015 at 04:50:37AM +0000, Jindal, Sonika wrote:
> > >>Hi Daniel,
> > >>
> > >>That patch was already merged:
> > >>http://lists.freedesktop.org/archives/intel-gfx/2015-July/071142.htm
> > >>l
> > >>
> > >>For SKL, the above patch helped in getting the correct ISR bits set.
> > >>One option is to enable the HDMI optimization from VLV onwards.
> > >>I don't have an ivb machine to try out the issue.
> > >
> > >ivb is simple the machine I have here, but when we tried this the 
> > >last time around we had reports for all platforms (your patch still 
> > >doesn't cite the relevant sha1 btw). I think there are 3 possible explanations:
> > >
> > Yes, I don't know which were those patches and how to find them..
> 
> git blame (recursively) and git log on intel_hdmi.c will tell you the story. I require all these extensive git commit messages because I dig them out daily. Also git log --pickaxe (well I use the equivalent in the gitk gui). If these tools are generally unknown in the vpg display team then we absolutely need to do a training session about them, they're extremely powerful and useful to dig out the history of the i915 code.
> 
> > >a) we do something wrong with hpd handling on these platforms. That 
> > >seems to be the explanation you favour (with the gen >= 7 checks and 
> > >all that), but I think it's very unlikely: On each platform where we 
> > >had reports of hpd being broken there was also machines where hpd works perfectly fine.
> > >
> > Not sure, I will find one ivb system and try on that.
> > 
> > >b) There's broken HDMI (or DVI) sinks out there. If that's the case 
> > >we can never merge your patch.
> > I doubt this because we have tested these patches with many sinks in 
> > the past with VLV/CHV.
> > >
> > >c) There's something in vbt or somewhere else that tells the windows 
> > >driver whether using hpd or not is ok (and the hpd problem is 
> > >actually an issue with certain OEM machines ...).
> > >
> > No, nothing like that.
> > 
> > >I hoped that with your hpd handling fix we'd have some indication 
> > >that our hpd troubles are of type a). But since I tested with your 
> > >patch that didn't work out.
> > >
> > >And until we have some evidence that our hpd troubles aren't type b) 
> > >I really don't want to merge any patch which relies upon hpd bits for hdmi.
> > >-Daniel
> > >
> > I will try on ivb.
> 
> I don't think it's ivb specific, since we do have ivb machines where hpd works perfectly fine. Same for every other platform. The only thing which seems common is that DP+ connectors work, but some of the hdmi-only connectors fail. That's why I wondered whether there's something i915 does different than the windows driver. In case you can get hold of one, the broken laptop I have here is an Asus UX31A with ivb.
> -Daniel
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch
> _______________________________________________
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> Intel-gfx@lists.freedesktop.org
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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