Virtualization - Jul 2023 - [PATCH RFC v1 00/52] drm/crtc: Rename struct drm_crtc::dev to drm_dev

On Wed, Jul 12, 2023 at 01:02:53PM +0200, Uwe Kleine-K?nig
wrote:
> > Background is that this makes merge conflicts easier to handle and
detect.
> 
> Really?
FWIW, I agree with Christian here.
> Each file (apart from include/drm/drm_crtc.h) is only touched once. So
> unless I'm missing something you don't get less or easier conflicts
by
> doing it all in a single patch. But you gain the freedom to drop a
> patch for one driver without having to drop the rest with it.
Not really, because the last patch removed the union anyway. So you have
to revert both the last patch, plus that driver one. And then you need
to add a TODO to remove that union eventually.
> So I still like the split version better, but I'm open to a more
> verbose reasoning from your side.
You're doing only one thing here, really: you change the name of a
structure field. If it was shared between multiple maintainers, then
sure, splitting that up is easier for everyone, but this will go through
drm-misc, so I can't see the benefit it brings.

Maxime
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Hello Maxime,

On Wed, Jul 12, 2023 at 02:52:38PM +0200, Maxime Ripard
wrote:
> On Wed, Jul 12, 2023 at 01:02:53PM +0200, Uwe Kleine-K?nig wrote:
> > > Background is that this makes merge conflicts easier to handle
and detect.
> > 
> > Really?
> 
> FWIW, I agree with Christian here.
> 
> > Each file (apart from include/drm/drm_crtc.h) is only touched once. So
> > unless I'm missing something you don't get less or easier
conflicts by
> > doing it all in a single patch. But you gain the freedom to drop a
> > patch for one driver without having to drop the rest with it.
> 
> Not really, because the last patch removed the union anyway. So you have
> to revert both the last patch, plus that driver one. And then you need
> to add a TODO to remove that union eventually.
Yes, with a single patch you have only one revert (but 194 files changed,
1264 insertions(+), 1296 deletions(-)) instead of two (one of them: 1
file changed, 9 insertions(+), 1 deletion(-); the other maybe a bit
bigger). (And maybe you get away with just reverting the last patch.)

With a single patch the TODO after a revert is "redo it all again (and
prepare for a different set of conflicts)" while with the split series
it's only "fix that one driver that was forgotten/borked" +
reapply that
10 line patch. As the one who gets that TODO, I prefer the latter.

So in sum: If your metric is "small count of reverted commits",
you're
right. If however your metric is: Better get 95% of this series' change
in than maybe 0%, the split series is the way to do it.

With me having spend ~3h on this series' changes, it's maybe
understandable that I did it the way I did.

FTR: This series was created on top of v6.5-rc1. If you apply it to
drm-misc-next you get a (trivial) conflict in patch #2. If I consider to
be the responsible maintainer who applies this series, I like being able
to just do git am --skip then. 

FTR#2: In drm-misc-next is a new driver
(drivers/gpu/drm/loongson/lsdc_crtc.c) so skipping the last patch for
now might indeed be a good idea.
> > So I still like the split version better, but I'm open to a more
> > verbose reasoning from your side.
> 
> You're doing only one thing here, really: you change the name of a
> structure field. If it was shared between multiple maintainers, then
> sure, splitting that up is easier for everyone, but this will go through
> drm-misc, so I can't see the benefit it brings.
I see your argument, but I think mine weights more.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-K?nig            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |
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