Re: [RFC v2 1/8] video: tegra: Add nvhost driver

[Thierry Reding <thierry.reding-RM9K5IK7kjKj5M59NBduVrNAH6kLmebB@public.gmane.org>]

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On Sat, Dec 01, 2012 at 01:44:41PM +0200, Terje Bergström wrote:
> On 30.11.2012 10:50, Lucas Stach wrote:
> > I'm with Thierry here. I think there is a fair chance that we won't get
> > the API right from the start, even when trying to come up with something
> > that sounds sane to everyone. It's also not desirable to delay gr2d
> > going into mainline until we are all completely satisfied with the API.
> > 
> > I also fail to see how host1x module being in the DRM directory hinders
> > any downstream development. So I'm in favour of keeping host1x besides
> > the other DRM components to lower the burden for API changes and move it
> > out into some more generic directory, once we feel confident that the
> > API is reasonable stable.
> 
> host1x module being in DRM directory hinders using nvhost from anywhere
> outside DRM in both upstream and downstream.

That's not true. Nothing keeps the rest of the kernel from using an API
exported by the tegra-drm driver.

> I also don't like first putting the driver in one place, and then
> moving it with a huge commit to another place.

Hehe, you're doing exactly that in this patch series. =)

> We'd just postpone exactly the problems that were indicated earlier:
> we'd need to synchronize two trees to remove code in one and add in
> another at the same time so that there wouldn't be conflicting host1x
> drivers. I'd rather just add it in final place once, and be done with
> it.

Yes, there would be a certain amount of synchronization needed, but as
Stephen correctly pointed out we could do that move through one tree
with the Acked-by of the other maintainer. The point is that we need to
do this once instead of everytime the API changes.

> But if it's a make-it-or-brake-it for upstreaming, I can move it to be a
> subdirectory under drivers/gpu/drm/tegra. Would this mean that we'd
> modify the MAINTAINER's file so that the tegradrm entry excludes host1x
> sub-directory, and I'd add another one which included only the host1x
> sub-directory? The host1x part would be Supported, whereas rest of
> tegradrm is Maintained.

An entry for drivers/gpu/drm/tegra/host1x would override an entry for
drivers/gpu/drm/tegra so no need to exclude it. That said, there's no
way to exclude an subdirectory in MAINTAINERS that I know of.

My main point for keeping host1x within tegra-drm for now was that it
could possibly help speed up the inclusion of the host1x code. Seeing
that there's still a substantial amount of work to be done and a need
for discussion I'm not sure if rushing this is the best way. In that
case there may be justification for putting it in a separate location
from the start.

Thierry

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