Re: [Freedreno] [PATCH RFC v1 00/52] drm/crtc: Rename struct drm_crtc::dev to drm_dev

[Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxxxxxxx>]

On 13/07/2023 16:09, Thomas Zimmermann wrote:
> Hi
>
> Am 13.07.23 um 16:41 schrieb Sean Paul:
> > On Thu, Jul 13, 2023 at 9:04 AM Uwe Kleine-König
> > <u.kleine-koenig@xxxxxxxxxxxxxx> wrote:
> > > hello Sean,
> > >
> > > On Wed, Jul 12, 2023 at 02:31:02PM -0400, Sean Paul wrote:
> > > > I'd really prefer this patch (series or single) is not accepted. This
> > > > will cause problems for everyone cherry-picking patches to a
> > > > downstream kernel (LTS or distro tree). I usually wouldn't expect
> > > > sympathy here, but the questionable benefit does not outweigh the cost
> > > > IM[biased]O.
> > > I agree that for backports this isn't so nice. However with the split
> > > approach (that was argumented against here) it's not soo bad. Patch #1
> > > (and similar changes for the other affected structures) could be
> > > trivially backported and with that it doesn't matter if you write dev or
> > > drm (or whatever name is chosen in the end); both work in the same way.
> > Patch #1 avoids the need to backport the entire set, however every
> > change occuring after the rename patches will cause conflicts on
> > future cherry-picks. Downstream kernels will have to backport the
> > whole set. Backporting the entire set will create an epoch in
> > downstream kernels where cherry-picking patches preceding this set
> > will need to undergo conflict resolution as well. As mentioned in my
> > previous email, I don't expect sympathy here, it's part of maintaining
> > a downstream kernel, but there is a real cost to kernel consumers.
> >
> > > But even with the one-patch-per-rename approach I'd consider the
> > > renaming a net win, because ease of understanding code has a big value.
> > > It's value is not so easy measurable as "conflicts when backporting",
> > > but it also matters in say two years from now, while backporting
> > > shouldn't be an issue then any more.
> > You've rightly identified the conjecture in your statement. I've been
> > on both sides of the argument, having written/maintained drm code
> > upstream and cherry-picked changes to a downstream kernel. Perhaps
> > it's because drm's definition of dev is ingrained in my muscle memory,
> > or maybe it's because I don't do a lot of upstream development these
> > days, but I just have a hard time seeing the benefit here.
> I can only second what Sean writes. I've done quite a bit of backporting 
> of DRM code. It's hard already. And this kind of change is going to to 
> affect almost every backported DRM patch in the coming years. Not just 
> for distribution kernels, but also for upstream's stable series. It's 
> really only possible to do this change over many releases while keeping 
> compatible with the old name. So the more I think about it, the less I 
> like this change.
I've done my share of backporting, and still am doing it, so I can say I 
dislike it as much as anyone, however.. Is this an argument which the 
kernel as a wider entity typically accepts? If not could it be a 
slippery slope to start a precedent?
It is a honest question - I am not familiar if there were or were not 
any similar discussions in the past.
My gut feeling is that *if* there is a consensus that something 
_improves_ the code base significantly, backporting pains should 
probably not be weighted very heavily as a contra argument.
Regards,

Tvrtko