Re: [PATCH v2 10/11] drm/qxl: rework cursor plane

From: Thomas Zimmermann
Date: Thu Feb 18 2021 - 11:12:13 EST


Hi

Am 18.02.21 um 12:50 schrieb Gerd Hoffmann:
Hi,

I'm still trying to wrap my head around the qxl cursor code.

Getting vmap out of the commit tail is good, but I feel like this isn't
going in the right direction overall.

In ast, these helper functions were only good when converting the drvier to
atomic modesetting. So I removed them in the latst patchset and did all the
updates in the plane helpers directly.

I see the helper functions more as a way to get some structure into the
code flow. The callbacks are easier to read if they just call helper
functions for stuff which needs more than a handful lines of code
(patch 9/11 exists for the same reason).

The helpers also make it easier move work from one callback to another,
but that is just a useful side-effect.

I had considered making that two separate patches, one factor out code
into functions and one moving the calls. Turned out to not be that easy
though, because the old qxl_cursor_atomic_update() code was a rather
hairy mix of qxl_create_cursor() + qxl_primary_apply_cursor() +
qxl_primary_move_cursor().

For cursor_bo itself, it seems to be transitional state that is only used
during the plane update and crtc update . It should probably be stored in a
plane-state structure.

Some of the primary plane's functions seem to deal with cursor handling.
What's the role of the primary plane in cursor handling?

It's a quirk. The qxl device will forget the cursor state on
qxl_io_create_primary(), so I have to remember the cursor state
and re-establish it by calling qxl_primary_apply_cursor() again.

So I'm not sure sticking this into plane state would work. Because of
the quirk this is more than just a handover from prepare to commit.

For now, I suggest to merge patch 1 to 8 and 11; and move the cursor patches
into a new patchset.

I can merge 1-8, but 11 has to wait until the cursor is sorted.
There is a reason why 11 is last in the series ;)

I'd like ot hear Daniel's opinion on this. Do you have
further plans here?

Well. I suspect I could easily spend a month cleaning up and party
redesign the qxl driver (specifically qxl_draw.c + qxl_image.c).

I'm not sure I'll find the time to actually do that anytime soon.
I have plenty of other stuff on my TODO list, and given that the
world is transitioning to virtio-gpu the priority for qxl isn't
that high.

Well, in that case:

Acked-by: Thomas Zimmermann <tzimmermann@xxxxxxx>

for patches 9 and 10. Having the vmap calls fixed is at least worth it.

Best regards
Thomas


So, no, I have no short-term plans for qxl beyond fixing pins +
reservations + lockdep.

take care,
Gerd

_______________________________________________
dri-devel mailing list
dri-devel@xxxxxxxxxxxxxxxxxxxxx
https://lists.freedesktop.org/mailman/listinfo/dri-devel


--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer

Attachment: OpenPGP_signature
Description: OpenPGP digital signature