Re: i915 drm patches in LTS 4.4.x ?

[Willy Tarreau <w@1wt.eu>]

On Mon, Jul 18, 2016 at 11:41:02PM +0000, Joakim Tjernlund wrote:
> On Mon, 2016-07-18 at 13:52 -0700, Greg KH wrote:
> > On Mon, Jul 18, 2016 at 02:21:45PM +0000, Joakim Tjernlund wrote:
> > > I wonder if the inflow of such patches has stopped or if they are just
> > > batched/saved for later?
> > 
> > I only see 5 pending i915 patches in my stable queue at the moment, not
> 
> I have a hard time seeing any i915 patches in your queue, must get glasses :)

Those you see are the ones Greg could already merge in his branches. He
sees them in his mailbox.

> > many at all.��Was there something specific you were looking for that did
> > not get merged?
> >�
> 
> We have some HP Broadwell laptops which has a problem with external monitors,
> they go blank/off intermittently. I think/hope this has been fixed upstream by now but I not sure.
> One path caught my eye though was this:
> � drm/i915: Revert DisplayPort fast link training feature
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/drivers/gpu/drm/i915?id=34511dce4b35685d3988d5c8b100d11a068db5bd

Did you try it or at least the kernel which contains it ? It is important
for stable branches (especially LTS ones) to have a good reason for
backporting a patch because there's always a risk to break some setups.
If you know the patch above improves your situation, it's a lot better
than just hoping it will improve it.

Overall the process is simple : if the latest kernel still doesn't work
for you, you want to report your breakage to the subsystem maintainers
who may have an idea how to fix it and who may request further info from
you. If the latest kernel works, you can try to find which patch made it
work (git bisect helps here) and ask for its backport. If finding which
patch fixes your problem is too difficult, asking the subsystem maintainers
can often help because if they recently fixed the problem they'll often
recognize the same issue in your description and will spot the relevant
patch.

Regards,
Willy