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

[Sean Paul <seanpaul@xxxxxxxxxxxx>]

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 appreciate your engagement on the topic, thank you!

Sean

>
> Thanks for your input, best regards
> Uwe
>
> --
> Pengutronix e.K.                           | Uwe Kleine-König            |
> Industrial Linux Solutions                 | https://www.pengutronix.de/ |