Re: [PATCH 10/10] gpu: host1x: Optionally block when acquiring channel

[Mikko Perttunen]

On 12.11.2017 13:23, Dmitry Osipenko wrote:
> On 11.11.2017 00:15, Dmitry Osipenko wrote:
> > On 07.11.2017 18:29, Dmitry Osipenko wrote:
> > > On 07.11.2017 16:11, Mikko Perttunen wrote:
> > > > On 05.11.2017 19:14, Dmitry Osipenko wrote:
> > > > > On 05.11.2017 14:01, Mikko Perttunen wrote:
> > > > > > Add an option to host1x_channel_request to interruptibly wait for a
> > > > > > free channel. This allows IOCTLs that acquire a channel to block
> > > > > > the userspace.
> > > > >
> > > > > Wouldn't it be more optimal to request channel and block after job's pining,
> > > > > when all patching and checks are completed? Note that right now we have locking
> > > > > around submission in DRM, which I suppose should go away by making locking fine
> > > > > grained.
> > > >
> > > > That would be possible, but I don't think it should matter much since contention
> > > > here should not be the common case.
> > > >
> > > > > Or maybe it would be more optimal to just iterate over channels, like I
> > > > > suggested before [0]?
> > > >
> > > > Somehow I hadn't noticed this before, but this would break the invariant of
> > > > having one client/class per channel.
> > >
> > > Yes, currently there is a weak relation of channel and clients device, but seems
> > > channels device is only used for printing dev_* messages and device could be
> > > borrowed from the channels job. I don't see any real point of hardwiring channel
> > > to a specific device or client.
> >
> > Although, it won't work with syncpoint assignment to channel.
>
> On the other hand.. it should work if one syncpoint could be assigned to
> multiple channels, couldn't it?

A syncpoint can only be mapped to a single channel, so unfortunately 
this won't work.

Mikko

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