Re: [PATCH] drm/amdgpu: fix regression on CIK (v2)

[Greg KH <gregkh@linuxfoundation.org>]

On Tue, Mar 22, 2016 at 04:31:30PM -0400, Alex Deucher wrote:
> On Tue, Mar 22, 2016 at 4:27 PM, Greg KH <gregkh@linuxfoundation.org> wrote:
> > On Tue, Mar 22, 2016 at 04:14:30PM -0400, Alex Deucher wrote:
> >> On Tue, Mar 22, 2016 at 4:11 PM, Greg KH <gregkh@linuxfoundation.org> wrote:
> >> > On Tue, Mar 22, 2016 at 03:48:18PM -0400, Alex Deucher wrote:
> >> >> From: Grigori Goronzy <greg@chown.ath.cx>
> >> >>
> >> >> This fix was written against drm-next, but when it was
> >> >> backported to 4.5 as a stable fix, the driver internal
> >> >> structure change was missed.  Fix that up here to avoid
> >> >> a hang due to waiting for the wrong sequence number.
> >> >>
> >> >> v2: agd: fix up commit message
> >> >>
> >> >> Signed-off-by: Grigori Goronzy <greg@chown.ath.cx>
> >> >> Cc: stable@vger.kernel.org
> >> >> Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
> >> >> ---
> >> >>
> >> >> Hi Greg,
> >> >>
> >> >> The code is correct for 4.6, this fix should be applied to
> >> >> 4.5 and older stable kernels.
> >> >
> >> > What is the patch in 4.6 that made it "correct"?  I would much rather
> >> > take that than something else.
> >>
> >> It's correct as is for 4.6.  I cherry-picked it out of my drm-next
> >> tree into 4.5 since it was a bug fix, but missed the internal driver
> >> structure change in drm-next that was not in 4.5.
> >
> > I'm sorry, I don't understand at all what you mean here :(
> >
> > What changed between 4.5.0 and 4.6-rc1 that made 4.5 "broken"?  What
> > fixed it in 4.6-rc1?
> 
> The patch was written and tested against drm-next, but I cherry-picked
> it to 4.5 as is since it was a bug fix.  However, I missed the
> internal driver structure change that it depended on.  Now that
> drm-next has been merged into 4.6 (including the driver structure
> change), the code from 4.5 works fine.  However 4.5 and older kernels
> are broken since they don't have the changes for 4.6.

I still don't understand.  What is the commit in Linus's tree that
matches this change?  Why can't I just cherry-pick that patch instead of
this "custom" one?

thanks,

greg k-h